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Upmanu Lall Recognized as a Fellow of the American Geophysical Union

American Geophysical Union Fall Meeting - Tue, 12/19/2017 - 10:03
upmanu lall onstage at ceremony

Upmanu Lall, director of the Columbia Water Center, is honored onstage as an AGU fellow.

Upmanu Lall, director of the Columbia Water Center, was one of 61 scholars to be honored by the American Geophysical Union (AGU) last week.

Each year, the organization recognizes just 0.01 percent of its members as AGU Fellows. This title is reserved for scientists who have “made exceptional scientific contributions and gained prominence in their respective fields of Earth and space sciences.”

The organization announced this year’s class of Fellows in July, but the awardees were commemorated in a ceremony and reception on Wednesday at the AGU meeting in New Orleans. Robin Bell, a geophysicist at Columbia’s Lamont-Doherty Earth Observatory and president-elect of AGU, presented the class of Fellows.

Lall’s work focuses on global water scarcity, predicting and mitigating floods, and developing sustainable water management strategies. At the ceremony, AGU praised his “incisive contributions to the understanding and predictability of hydrologic processes at regional and global scales.” But Lall feels his colleagues deserve much of the credit. “It’s really a recognition for all the students and postdocs who have been working with me,” he says.

Through the America’s Water project, the Columbia Water Center is working to build a comprehensive picture of water sources and stresses in the U.S. Up next, Lall and his team plan to address the growing number of communities across the U.S. who are losing access to safe drinking water and sanitation.

“AGU Fellows are recognized for their outstanding contributions to scholarship and discovery in the Earth and space sciences,” Eric Davidson, president of AGU, said in a statement in July. “Their work not only expands the realm of human knowledge, but also contributes to the scientific understanding needed for building a sustainable future.”

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Air Pollution May Kill More Africans Than HIV/AIDS

American Geophysical Union Fall Meeting - Mon, 12/18/2017 - 11:59
fire in an agricultural field

Farmers often use fire to clear agricultural fields, but the practice adds to air pollution. Here, a man tends a fire in a Louisiana field. Photo: Chloe Gao

AIDS and malaria epidemics receive much attention from international health organizations, but a sneakier killer is on the loose in Africa. Air pollution may now be the continent’s number one killer, according to a forthcoming study. Susanne Bauer, an Earth Institute affiliate who models atmospheric composition at NASA’s Goddard Institute for Space Studies, presented these findings at a meeting of the American Geophysical Union on Thursday.

In sub-Saharan Africa, the widespread practice of burning crop residues helps to clear stubble from fields and fertilize the soil. “It’s really, really cheap to treat your fields after the harvesting season with fires,” explained Bauer during her presentation. But where there’s fire, there’s smoke. The practice releases fine particles into the air that can harm human health, and sub-Saharan Africa alone produces about a third of the planet’s burning biomass emissions. Bauer and her colleagues set out to learn more about the particles’ origins, chemistry, and health effects.

The Biggest Killer

The team used a climate model and satellite data to map where the biomass burning takes place. They tracked where the smoke from those fires ends up, and studied the distribution of gases and harmful particulates that come from other sources, such as industry and nature. Then they fed the data into an economic health model to estimate how many lives each type of pollution would shorten. The model takes into account factors such as population density, age distribution, and risk factors from other diseases.

Bauer and her colleagues calculated that the largest portion of Africa’s air pollution-related deaths came from a surprising source. “The biggest killer on that continent is nature, because of the gigantic dust sources around the Sahara,” said Bauer.

Particles smaller than 2.5 microns—about half as wide as a red blood cell—can lodge themselves in human airways. Once inside, they increase a person’s risk of lung cancer, heart attack, lung disease, stroke, heart disease, and more.

The team calculated that Saharan dust and other natural pollutants cause 1.2 million Africans to die prematurely every year. That’s more than AIDS, which kills around 760,000 Africans per year, on average.

In 2015, AIDS was unseated as the leading cause of death in Africa. It was replaced by lower respiratory infections, such as pneumonia and bronchitis, which claim one million African lives per year.

By these estimates, air pollution from the Sahara is the number one killer in Africa. In addition, studies suggest that some types of air pollution are linked to respiratory infections.

Other Dangers

Industrial and urban emissions were the second deadliest source of air pollution. They claim 324,000 lives per year, according to the team’s estimates. Gases emitted by vehicles and factories—such as ozone, carbon monoxide, sulfur oxides and sulfates—as well as soot and organic carbon were mostly to blame. This manmade pollution ranks between meningitis and malaria in Africa’s leading causes of death.

Although burning forests and fields created the largest amount of air pollutants in the study, the practice takes place in areas where population density is low. As a result, biomass burning ranked as the third largest source of air pollution-related deaths. It causes an estimated 70,000 premature deaths per year.

One weakness of the study, said Bauer, is that she and her colleagues assumed all types of fine particles had equal toxicity. That may not be the case in reality. However, scientists don’t know much about each particle’s specific effects on human death rates.

Growing Awareness

“I think it’s very striking that air pollution’s overall mortality is the same order of magnitude as AIDS,” said Bauer. “There are a lot of initiatives to fight AIDS, to fight malaria, but air pollution is certainly under-addressed on that continent.”

Part of the reason for its obscurity may be that premature deaths from air pollution are hard to pinpoint. You can’t diagnose them like you can for malaria and AIDS. The negative effects of air pollution can manifest in a variety of ways, and exacerbate conditions that can have multiple causes.

“I don’t think society understood how dangerous it is,” she said.

The team calculated that interventions—such as reducing pollution from industrial sources, improving land management techniques, distributing masks, and informing people about the dangers of dust storms—could save 350 thousand lives each year.

Tackling air pollution in Africa will not be easy. Many nations already face political, economic, and social challenges, on top of other known health problems. But Bauer says awareness about the dangers of air pollution is growing, and that’s the first step toward fixing the problem.

The team is preparing this research for submission in a peer-reviewed journal. Other contributors include Ulas Im from Aarhus University and Keren Mezuman from Columbia University.

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Enough is never enough

By Julian Spergel

The best way to move the Icepod with all its instruments is with the help of a sledge! (photo Susan Howard)

After what seemed a multitide of small setbacks due to weather and plane repairs, Rosetta’s third season came to an end amid a flurry of last minute flights, packing, and saying goodbye to our new friends. The last few days flew by as we cleared out our tent on Williams Field, disassembling our equipment, and returning borrowed equipment to the proper departments. Packing down here is done carefully. Everything we had brought down to the tent had to be checked off a list, packed in its proper container, labelled for shipping, placed on a metal pallet, weighed and labelled by weight for packing, put back on a metal pallet, and finally sent off for shipping. I’m glad my own things did not need to go through such a rigorous process, though I bet I would lose fewer possessions if I was this meticulous! Among the fourteen of us, the whole process went by quickly, and the tent that we had considered our little corner of Antarctica emptied in just two days.

Some of the iced team from left to right Chris B. one of the IcePod engineers, and Grant and Martin, two of the gravimeter operators. (Photo – Susan Howard)

But enough is never enough when you have traveled so far for data! Almost from nowhere we were given a surprise opportunity to fly one of our survey lines the second-to-last day of our Antarctic season and we jumped at it! While it wasn’t possible to unpack all of our instruments, the careful packing and labeling of the pallets allowed us to readily locate what we needed. In a final burst of unpacking we had our gravimeters together and were ready to go. There is always time for more data.

For the return trip I was tasked with carrying one of two copies of our scientific data (there is always redundancy in data this hard to collect)! I carried a hard plastic suitcase filled with a dozen thumbdrives and over seventy hard drives, equaling seventy pounds of memory, from McMurdo Station, Antarctica to New York City. Some readers may be wondering why we used such a physically demanding method of sending data home. Even in 2017, there is no means of transferring data as safely and as quickly as a graduate student carrying a bag of hard drives! After some huffing and puffing, and some odd looks from security personnel, I delivered the data to Lamont-Doherty Earth Observatory outside NYC for our archivists to put onto the server.

Map of Rosetta flight lines for the three seasons of work. Spacing at 10 km resolution for the bottom (northern) and most of the southern section of the map. Other areas are at 20 km spacing.

What have we accomplished this third field season? Ultimately, after flight cancellations due to over a week of harsh weather and cancellations due to airplane technical issues, we were able to complete fourteen of the eighteen flights we planned for this Antarctic season. In total, we had roughly two hundred sixty hours of flying over an area the size of Texas. The goal of the Rosetta-Ice project was to use airplane-mounted sensors to create a 10-km resolution grid of geophysical measurements of the Ross Ice Shelf’s glaciology and geology. After three Antarctic field seasons, our mapping is finished. In the northern (bottom) two-thirds of our survey grid we have created a 10-km resolution map, and in the remaining third of the surveyed area we have a 20 km-resolution map. The data collection phase of our project is over, but the analysis of the data is ongoing. With the new, higher resolution map of the Ross Ice Shelf and the underlying seafloor, previously unseen small-scale features can be identified and studied. Research assistant Isabel Cordero has been working on ‘picking’ the ice layers of the radar echograms, identifying the layers of accumulated ice from the various glacial sources, for the past year. I’m looking forward to the day when, in a few months time, we print out all the radar echograms that we collected, with the ice layers and interesting points labelled for everyone to peruse.

Radar flight line L700, a slice across the front of the Ross Ice Shelf that shows the separate ice packets from series of glaciers around the shelf. On the western side (the left) Roosevelt Island is clearly identifiable pushing up under the ice.

In the coming months, we will be presenting our initial findings. But for several years we will continue to dig in to the collected data, as we seek to answer the research questions that led our project in the beginning. The goals for Rosetta-Ice’s were to answer questions about the conditions on top of and inside the Ross Ice Shelf’s ice, as well as the conditions in the ocean water circulation and rocky bed beneath the ice, and look at linkages. The most exciting aspect of finishing a scientific project is not just what questions can be answered, but what new questions will develop as we learn more about the Ross Ice Shelf and Antarctica as a whole. For further updates about our project keep checking back to our project site. www.ldeo.columbia.edu/rosetta

The author, Julian Spergel on Castle Rock, Antarctica for a final look at the vast white continent before ‘wheels up’.

This will be my final blog entry, and I would like to finish on a personal anecdote. At the beginning of my time on this blog, I wrote about how coming to Antarctica was a personal goal of mine. On my last hike of my time in Antarctica, a five-hour trek to a large rock crag called “Castle Rock,” I had a moment where, as I looked out over the landscape, I felt a sense of completion. Standing in the middle of a flat, windswept field of snow and ice and watching the snow-covered volcano Mt. Erebus smoke white steam into the sunny blue sky, I thought: “This is Antarctica. All my life, I have imagined what it would be like to be here, and here I am, and it ia even more majestic than I thought.” I did my best to memorize every detail of the scene: the cold, the silence, the vividness of the colors. There was so much of Antarctica that I would never be able to see, and the freshness of my memories of being here would soon fade, but if I could just remember this moment, it would be enough.

I was so lucky to be able to visit this remote corner of our planet. I only wanted to return again soon, to see and learn more. Before I knew it, I was stepping out of the plane in Christchurch, inhaling my first scents of plant life in over a month.

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery. He graduated with a B.S. in Geophysical Sciences from the University of Chicago in 2016. He has been involved with a number of diverse projects and has been interested in polar studies since early in his career. His fieldwork has brought him north to the Svalbard Archipelago and south to McMurdo Station, Antarctica.

Learn more about previous years’ research, here.

For more on this project, please visit the project website: http://www.ldeo.columbia.edu/rosetta

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What Caused the Great Famine?

American Geophysical Union Fall Meeting - Fri, 12/15/2017 - 11:32
drought great famine

From 1876-78, droughts cause crop failures around the world, causing millions to die. Photo: dasroofless via Flickr

From 1876 to 1878, the Great Famine killed between 30 and 60 million people around the world. Drought enveloped much of the planet, causing food shortages all the way from Brazil to India and China, and wiping out approximately three percent of the global population.

Climate scientist Deepti Singh from Columbia University’s Lamont-Doherty Earth Observatory recalls reading about the droughts’ devastation and wondering, “What could cause something like this? And what’s the likelihood that it could happen again in the coming decades?”

She and her colleagues are quantifying the extent and severity of the global drought, and trying to find out what made it so severe. She presented the research on Friday at the meeting of the American Geophysical Union in New Orleans, Louisiana.

The Great Famine was “arguably the worst environmental disaster to ever befall humanity,” the team notes in a forthcoming paper. It “helped create the global inequalities that would later be characterized as ‘first’ and ‘third worlds’.” Understanding the drought’s driving forces is important, says Singh, since they could strike again at any time—perhaps worse than ever, since hotter temperatures make droughts more intense.

Scientists have long suspected that El Niño was partially to blame for the global famine. Driven by temperatures in the equatorial Pacific Ocean, El Niño is a climate pattern that often comes with warm and dry conditions in India, Australia, and South America. In their paper (which has not yet been published), Singh and her colleagues provide some of the first quantitative evidence that this environmental catastrophe was likely driven by the strongest El Niño that human instruments have ever measured. Other record-breaking conditions may have been at play as well, they find.

A Global Problem
great famine causes people in india to starve

The Great Famine killed an estimated 12 to 29 million people in India. Image: Wikimedia Commons

To find out exactly where, when, and how long the droughts occurred, as well as their severity, the researchers turned to tree-ring based drought atlases. Tree rings grow thicker during wet years, so old trees can provide a history of past climate conditions. Edward Cook, co-author and director of Columbia’s Tree Ring Lab, developed three of the atlases used in the paper. Rain gauge data, some of which goes back 175 years, also indicated how scarce water was at the time of the drought.

The team’s findings suggest that the 1876-78 droughts extended far beyond Brazil, India, and China, although that’s where famine struck the hardest. The search turned up evidence for dry conditions in Egypt, Morocco, Australia and even southwestern and eastern North America. Tree rings suggested Asia’s drought was the worst in 800 years or more.

Prelude to Disaster

To find out what made the conditions so severe, the researchers looked at sea surface temperature data collected by sailors going back as far as the 1870s.

Sea surface temperatures confirmed that there was indeed an intense El Niño that persisted for the larger part of two years of the Great Famine (1877-78). But the extreme El Niño may have been primed by cooler waters in the central tropical Pacific from 1870 to 1876. This prolonged period of coolness—the longest on the record—may have led to immense buildup of warm water in the western tropical Pacific. This ended in a strong La Niña event in 1875-76. The La Niña kicked off dry conditions in India, Mexico and the southwestern U.S., then discharged into a strong El Niño, which brought along more dryness across a large fraction of the globe.

“It’s like a pendulum,” explains Singh. “If you keep pushing it in one direction, further and further from the center, and then release it, it’s going to go to the extreme in the other direction.”

Oceanic Accomplices

El Niño didn’t work alone in generating the Great Famine. Singh and her colleagues found evidence of exceptional conditions in the Atlantic and Indian oceans as well.

In 1877, the Indian Ocean experienced exceptionally warm temperatures, particularly in its western portion, generating a dipole in sea surface temperatures. These contrasting conditions in the Indian Ocean can often lead to dry conditions in Australia and South Africa. But in 1877, the thermal contrast between the two halves was the strongest ever recorded before or since, which likely assisted El Niño in generating severe droughts in those regions.

In 1877 and 1878, the north Atlantic was the warmest it has ever been, according to records that date back to the 1850s. This may have pushed moisture-carrying atmospheric winds northward, away from the Brazilian Nordeste, which lost two million lives during the famine that followed.

Scientists disagree over whether El Niño could have triggered these effects in the Atlantic and Indian oceans. Maybe it was just bad luck that extreme conditions happened in all three oceans at once. But the oceans are all connected, and Singh and her colleagues suspect El Niño set off the cascade of effects.

“It’s hard to think that all of this was a coincidence,” Singh says.

Looking to the Future

All in all, the team concludes that a host of record-setting conditions—an intense and long-lasting El Niño, likely primed by a cool Pacific, and exacerbated by a warm Atlantic and strong thermal contrasts in the Indian Ocean—combined into the perfect storm that was the Great Famine. And it could happen again.

Since the conditions that cooked up the Great Famine arose from natural climatic variation, there’s nothing to stop a global drought from recurring. If those conditions were to arise again, they could again put global food security in jeopardy.

In fact, it could be worse the next time around. As the global thermostat rises, the warmer temperatures could make future droughts more severe, says Singh.

Next, she and her colleagues hope to find out how often events like this might happen in the future, how severe they might be, and which countries would be worst affected. Understanding what caused the global drought could help to predict and prepare for the next one, in hopes that it won’t trigger another global famine.

The study is currently is in preparation for submission to a peer-reviewed journal. Other authors include Richard Seager, Benjamin I Cook, Mark Cane and Mingfang Ting from Lamont-Doherty Earth Observatory, and Michael Davis from the University of California, Riverside.

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American Geophysical Union 2017: Key Events From the Earth Institute

American Geophysical Union Fall Meeting - Mon, 12/04/2017 - 14:35

A chronological guide to key talks and other events presented by Columbia University’s Earth Institute at the American Geophysical Union 2017 meeting. Unless otherwise noted, scientists are at our Lamont-Doherty Earth Observatory. For abstracts, see the Meeting Program. Reporters: contact scientists directly, or news editor Kevin Krajick, kkrajick@ei.columbia.edu 917-361-7766.

Emergence of a New Pacific Island: Analog to Mars?   Vicki Ferrini
In 2015, a brand-new island emerged in the Pacific’s Tonga chain, when a volcano exploded through the water line. NASA scientists are studying its evolution with satellite imagery, and Ferrini and colleagues have mapped the bathymetry around it from a ship. This is the first time a newly forming island has been so studied in real time. The observations open a new window onto earth processes, and also may serve as an analog to understanding similar-looking island-like features on Mars. Ferrini will speak at an AGU-sponsored press conference with NASA scientists Jim Garvin and Dan Slayback.
PRESS CONFERENCE: Evolution of a New Pacific Island May Unlock Secrets to Mars. Monday, Dec. 11, 9am, Press Conference Room
Scientists Map a New Volcanic Island

 Wildlife on the Move in a Warming Arctic  Scott LaPoint, Ruth Oliver
Fast warming in the arctic appears to be altering wildlife movement, behavior and ranges. LaPoint discusses tracking data showing that migratory golden eagles are arriving in northern breeding grounds earlier every spring. Oliver discusses automated bioacoustic networks that record bird calls at select far northern locations, allowing researchers to track changes in the arrival of many species. LaPoint will later join researchers from other institutions in a press conference to discuss climate-related changes among other species.
LaPoint: Monday, Dec. 11, 10:50-11:05am, Morial Center 356-357. B12C-03
Oliver: Monday, Dec. 11, 11:05-11:20am, Morial Center 356-357. B12C-04
PRESS CONFERENCE: Climate Change and Unexpected Consequences for Animal Populations. Monday, Dec. 11, 4pm, Press Conference Room

 Getting Under an Antarctic Ice Shelf  Robin Bell
AGU president-elect Bell will discuss the latest findings from the ROSETTA project, which is using instruments above and below the ice to produce new images of Antarctica’s Ross Ice Shelf, the ocean, its floor, and deep geologic structures. Among other things, the research is revealing that the shelf is melting from the top in some areas, but the bottom in others—differences that in some cases may be influenced by underlying geology.
Monday, Dec. 12, 4:12-4:15pm, Morial Center eLightning Area. C14B-04
Unlocking the Secrets of the Ross Ice Shelf

 Studying Lava With Drones and Neuroscience  Einat Lev
In 2016, Lev and colleagues trekked to Chile’s Quizapu volcano, site of South America’s largest historical lava flow, to map the vast surface in great detail via drone. Along with related work at volcanoes in Hawaii, Iceland and elsewhere, this research should yield new insights into natural controls on lava flows, and how people might deal with them. Lev and colleagues are also now about to simulate lava dynamics in the lab using materials and methods adapted from cutting-edge neuroscience experiments.
Tuesday, Dec. 12, 9:30-9:45am, Morial Center 208-209. V21A-07
Peering Into Chile’s Quizapu

 Facebook and the Mapping of Humanity Alexander deSherbinin, Robert Chen, Center for International Earth Science Information Network (CIESIN)
CIESIN scientists have partnered with Facebook to map human habitation and infrastructure at fine scales across the world. Facebook started the effort in order to locate billions of people not yet connected to the internet—information that can be applied to a wide variety of socioeconomic projects. De Sherbinin discusses information newly available in 30-meter resolution, and how institutions are working to use the data. Chen will discuss relatively new tools collecting data, including drones, cell phones, internet providers, satellites and citizen scientists, and new “big data” capabilities to process it.
Chen: Tuesday, Dec. 12, 10:50-11:05am, Morial Center 255-257. PA22A-03
De Sherbinin: Friday, Dec. 15, 9:09-9:21am, Morial Center 228-230. IN51H-06
Mapmakers Team With Facebook

 The Lamont-Doherty Earth Observatory Party
Traditionally on Tuesday night at AGU, staff and alumni of Lamont-Doherty Earth Observatory gather from around the world for a reunion. Journalists registered for AGU are welcome—a great chance to make contacts, hear the buzz about new work, and have fun.
Tuesday Dec. 12, 6:30-8:30pm, Lowes New Orleans, Louisiana Ballroom, 300 Poydras Street

 From Plate Tectonics to Nuclear Bombs Lynn Sykes
Seismologist Lynn Sykes has devoted much of his long career to detecting secret nuclear test explosions, and working to develop verifiable test-ban treaties. In his new book Silencing the Bomb: One Scientist’s Quest to Halt Nuclear Testing, he details the science and intrigues of his work. Sykes will sign copies at the Columbia University Press exhibit booth. He will also give a talk on his role in solidifying the theory of plate tectonics, when he mapped undersea earthquakes in the 1960s—subject of his second book, coming in 2018.
Silencing the Bomb signing: Wednesday, Dec. 13, 11am-12pm, Columbia University Press booth (#1552), Exhibition Hall
Tectonics: Wednesday, Dec. 13, 2:04-2:20pm, Morial Center E2. U33A-02 (Invited)

Unviable U.S. Dams Michelle Ho, Columbia Water Center, Richard Seager
Dams that supply water to the U.S. West were designed with little knowledge about the range, frequency and persistence of precipitation extremes. Scientists have since identified prehistoric droughts worse than any seen historically, and projections say the region will get drier as climate warms. In this light, Ho assesses the viability of existing dams. In a separate talk, Seager synthesizes the latest findings on regional climate, taking in studies of paleoclimate and plant physiology, and new revelations about the influence of the Pacific and Atlantic oceans. One concern: as the West dries, plants in natural ecosystems could adapt by sucking up more soil moisture, competing with humans for ever-scarcer water.
Ho: Wednesday, Dec. 13, 1:40-6pm, Morial Center Poster Halls D-F. NH33B-0246
Seager: Wednesday, Dec. 13, 2:04-2:22pm, Morial Center 343. PP33D-03
Michelle Ho: In a Land of Plenty, Big Water Problems
Richard Seager Sees Hand of Climate Change in Drought

 The Melting Himalayas Joshua Maurer  Mukund Rao
Due to lack of long-term observations, scientists have been unclear about how Himalayan glaciers as a whole are being affected by warming climate. By combining declassified films from old spy satellites with modern satellite imagery, Maurer and colleagues now have a 40-year record of changes in 1,000 glaciers spanning 2,000 kilometers. They say ice has been consistently wasting since 1975, and the rate has doubled since 2000. In a related study, Rao compares recent stream flows in the glacier-fed Indus River watershed with tree rings going back to 1452. Results suggest that since the 1980s, water flow has been greater than at any time in in the last 500 years, probably driven by increased glacier melt.
Rao: Thursday, Dec. 14, 9-9:15am, Morial Center 267-268. GC41G-05
Maurer: Friday, Dec. 15, 11:35-11:50am, Morial Center 275-277. C52A-06

Africa’s Air Pollution Problem Susanne Bauer, Goddard Institute for Space Studies
Sub-Saharan Africa produces a third of earth’s particulate pollution caused by biomass burning—yet the exact origins, chemistry and health effects of particles remain poorly known. Using satellite imagery and other resources, Bauer and colleagues have done a comprehensive study. She will discuss where particles come from, the number of people affected, and how pollution may work with other factors to cause premature death.
Thursday, Dec. 14, 11:05-11:20am, Morial Center 395-396. A42C-04

 A Newly Revealed Record El Niño, and a Killer Drought  Deepti Singh
The 1876-78 Great Famine killed more than 50 million people across Asia, Africa and South America–possibly the worst human environmental disaster ever. Blame often has been laid on socioeconomic factors of the colonial era, but the trigger was drought. Using tree rings, instrumental observations and sea-surface temperature reconstructions, Singh says that the drought resulted from the greatest El Niño yet identified, surpassing those of the 1980s ‘90s. Singh says it arose from natural conditions that could be repeated today, affecting multiple grain-producing regions simultaneously and undermining global food supplies.
Friday, Dec. 15, 8:45-9:00am, Morial Center 265-266. GC51F-04 (Invited)

 Andean Ecosystems: Early Climate Casualties? Daniel Ruiz-Carrascal, International Research Institute for Climate and Society
The world has agreed to limit the rise of global temperatures to 2 degrees C, but that may not be good enough for the high Andes. To study the effects of warming, Ruiz-Carrascal and colleagues have collated weather and biological data for decades across high-elevation South America. He will discuss evidence that many ecosystems are already ailing, due to both warming and human intrusions, and suggests they may start falling apart altogether at 1.5 degrees—a threshold we already are approaching.
Friday, Dec. 15, 1:40-6pm, Morial Center Poster Hall D-F. GC53A-0871
Climate Change Threatens Fragile Andes Ecosystem

 Films From the Field
Short films on the fieldwork of our scientists, shot on location, will be screened at the daily AGU Cinema. This year’s crop can also be viewed any time online at the links below.
Biblical Land, Killer Drought (2017) Along the shores of the Dead Sea, in an already sere and volatile land, a team from Jordan, Israel and the United States explores geologic evidence that repeats of ancient megadroughts could reshape the Mideast.
What the Vikings Can Teach Us About Climate Change (2017) Climatologists plumb the bottoms of deep lakes in Norway’s arctic Lofoten Islands, in search of clues to how Vikings survived and thrived here a thousand years ago, at the height of their power.
Sierra Glaciers and the Global Climate Puzzle (2017) Glacial geologists explore remnants of the last ice age in California’s high Sierras, in search of insights into how warming climate may affect water supplies for people far below.
AGU Cinema: 8am-12pm Monday, Tuesday. 8am-10am Wednesday, Thursday, Friday. Morial Center, First Floor, Sharing Science Room/Rivergate Room

 

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A Bit of Sun on an Antarctic Thanksgiving

Thanksgiving week at McMurdo has brought warm, clear weather, so it is hopeful we will have a full week of back-to-back flights in our second-to-last week. The weather was perfect for the annual Antarctic “Turkey Trot” 5k race. Rosetta Projects very own Chloe Gustafson won 1st place, and holds the honor of being the first woman to win the race!

Chloe Gustafson won 1st place in the Antarctic Turkey Trot and holds the honor of being the first woman to win the race!

Chloe Gustafson won 1st place in the Antarctic Turkey Trot and holds the honor of being the first woman to win the race!

The warm weather has also begun to melt the snow around the station, turning the snow mushy and revealing the dirt underneath the ice that we had forgotten was there. The landscape of McMurdo changed over the course of a number of hours, from ice- and snow-covered to “mud season.” As the ground surface becomes darker, it absorbs more heat, and the surrounding ice melts faster. This process called ice-albedo feedback is one that is driving a majority of the accelerated change in both poles.

Sea ice images collected from IcePod from the Rosetta Project.

Another rapidly changing part of the Antarctic landscape was observed during a recent Rosetta survey flight that skirted the edge of the ice shelf to observe sea ice, icebergs, and areas of persistent open water called ‘polynyas’. Icebergs are chunks of glacier that break off into the ocean. We saw ‘tabular icebergs’, boxy chunks of ice that still have sharp vertical walls after breaking off the ice shelf. On our flight, most of the icebergs I saw were frozen into the sea ice, like ice islands sticking out from a frozen ocean. Sea ice forms from the freezing of ocean water: small chunks of ice called ‘new ice’ grow and merge into sheets of thin sea ice, which then accumulate snow. While it is still in motion, the ice is called ‘drift ice,’ but once it freezes to the front of the ice shelf or the sea bed, it is called ‘fast ice.’ The fractured tiles of sea ice and dark water looked like stained glass, and it was incredible to see the variety of patterns and the shifting colors of light reflected in the icy seascape below.

Lidar image of se ice shot from the IcePod.

Lidar image of sea ice shot from the IcePod. The ice carries a look of intricately woven lace.

In collaboration with the University of San Antonio project Polynyas and Ice Production in the Ross Sea (PIPERS), we used IcePOD, our aircraft-mounted suite of sensors, to help measure the thickness of the sea ice and get a better understanding of temporal and spatial patterns of air-sea-ice interactions around the sea ice. The cracks and gaps in the sea ice were of special interest to the PIPERS scientists, who are studying the evolution of polynyas in the Ross Sea, which are caused by upwelling water or wind currents. You can learn more about PIPERS at their website.

//journals.plos.org/plosone/article?id=10.1371/journal.pone.0083476) Edwardsiella andrillae n. sp., lives with most of its column in the ice shelf, with only the tentacle crown extending into the seawater below. The ANDRILL 200 Coulman High Project (CHP) fieldwork in Antarctica during the austral spring and summer of 2010-2011 was funded by the U.S. National Science Foundation, Office of Polar Programs, and in New Zealand by the NZ Foundation for Research, Science and Technology. A. Close up of specimens in situ. Image captured by SCINI. B. “Field” of Edwardsiella andrillae n. sp. in situ. Image captured by SCINI. Red dots are 10 cm apart. https://doi.org/10.1371/journal.pone.0083476.g002

A new species of sea anemone Edwardsiella andrillae. Edwardsiella andrillae n. sp., lives with most of its column in the ice shelf, with only the tentacle crown extending into the seawater below. Image from The ANDRILL 200 Coulman High Project (CHP) fieldwork in Antarctica  2010-2011,  funded by the U.S. National Science Foundation, Office of Polar Programs, and in New Zealand by the NZ Foundation for Research, Science and Technology.
A. Close up of specimens in situ. Image captured by SCINI. B. “Field” of Edwardsiella andrillae n. sp. in situ. Image captured by SCINI. Red dots are 10 cm apart.

Understanding sea ice is important to understanding polar biology and understanding polar oceanography. The sea ice hosts a unique ecology of animals and bacteria. Penguins, seals, and other marine animals use the sea ice. Species of photosythetic plankton live on the bottoms of sea ice chunks. Famously, the ANDRILL project discovered a previously unknown species of sea anemone, /Edwardsiella andrillae/, that lives clinging to the underside of the sea ice in the Ross Sea. Sea ice plays a role in keeping the polar oceans cold, reflecting the Sun’s energy off its shiny white surfaces back into space. Lastly, as sea ice freezes, salt is squeezed out into the surrounding water, making it denser and thus causing it to sink. This downward push helps to drive the conveyor belt-like circulation of surface water from the Equator to the Poles and the bottom water circulation from the Poles to the Equator. This is called thermohaline circulation. Thus sea ice plays a role in the Earth’s oceans, both locally in the Antarctic and worldwide.

Why did the scientists of PIPERS want to use IcePod when flying over their sea ice study area? Not for the ice-penetrating radar, which looked very confusing after processing. Both the shallow and deep ice radar instruments are intended for looking through hundreds of feet of ice, not a few feet of sea ice. But our LiDAR (Light Detection And Ranging) returned some beautiful three-dimensional images of the sea ice-topography. They can use these high-definition images to study small details of the ice.

Ice threaded with leads of open water that show up dark black against the white ice. These dark areas absorb energy from the sun causing a feedback loop.

Ice threaded with leads of open water that show up dark black against the white ice. These dark areas absorb energy from the sun causing a feedback loop.

Flying over the sea ice was a treat for the flight’s passengers, myself included, but it was not the most interesting flight for the trip’s IcePod flight engineer, Tej Dhakal. I asked him what kinds of terrain are the most interesting to fly over as he is monitoring the instruments. He said that he enjoyed flying over areas where the instruments reveal hidden details: the Crary Ice Rise, a large mound of ice forming over a rise in the seabed below that is only really visible in the radar echograms, and the Siple Coast, where a sharp change in radar returns indicates precisely where the coastline sits, which is often different than what has been previously mapped. The Trans-Antarctic Mountains are interesting because there is a high density of crevassing. Hopefully this week’s remaining flights will add this kind of interest.

Wendell seal mother pops up from the hole in the ice to communicate with her pup.

Wendell seal mother pops up from the hole in the ice to communicate with her pup.

In seal news, the baby seal, who I’ve named Boopy, has grown much larger and is nearly ready to go for its first swim. Its mother popped out of the ice hole to yell at it to not bother the larger seal lying nearby.

For more information about Rosetta-Ice, check out our website and the archive of this blog. Have questions about Rosetta-Ice or about living and working in Antarctica? Feel free to email your question to juliansantarctica@gmail.com, and I will try to answer it in the next blog entry!

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and is blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery.

Wind, Snow and Ice: Summer in Antarctica

By Julian Spergel

The theme of the past week has been: Weather. Weather is of course always happening, but in the lingo of McMurdo Station, ‘weather’ means ‘bad weather.’ Over the past week, I’ve seen the accumulation of around six inches of very fluffy snow.Radar image from McMurdo weather website Nov. 21, 2017.

Radar image from McMurdo weather website Nov. 21, 2017.

Radar image from McMurdo weather website Nov. 21, 2017.

In the center of McMurdo Station, visibility has not yet decreased too much, but on Williams Field there were several days of Condition 1, the most extreme, with visibility of less than one hundred feet. In terms of temperature, it has not gotten too cold, with thermometer temperatures hovering between the mid-teens and low twenties Fahrenheit. Nevertheless, all flights have been grounded for nearly a week.

Windy and snow blowing! Conditions on Willy Field, Antarctica during the recent spat of bad weather. (J. Spergel)

When weather permits, the Rosetta team has been checking in on the instruments in our Williams Field tent and on the air plane, digging out the entrances to the tent, and remaining in a state of preparedness for our next flight opportunity. In between our check-ins the cargo staff went out to investigate and found the back doors of the tent blown open, letting in snow and cold. They relayed to us that the instruments are looking ok, and this was later confirmed by two of the members of the Rosetta team when they were able to make it down to the field.

Snow has blown up against the Rosetta Field station providing some good shoveling exercise for the team. Photo J. Spergel.

Snow has blown up against the Rosetta Field station providing some good shoveling exercise for the team. Photo J. Spergel.

It isn’t all bad news. The flights that were going to the South Pole were grounded as well, and the fresh fruits and vegetables that would have gone to them were served to McMurdo Station instead. We enjoyed fresh avocados at every meal for several days as snow blew outside! Their loss our gain!

This austral summer seems to be unusual, with unseasonably active weather. People who have been here in recent years note that the weather during November is normally clear. According to NOAA’s weather statistics for the period 1961-1990, McMurdo Station receives on average a little less than half an inch of snow water equivalent in November. This year, the McMurdo weather office measured nine inches of snow in the twenty-four hours between 1 A.M November 16th and 1 A.M November 17th. This would equal ~ a full in of snow/water equivalent in just 24 hours! It has been a snowy month.

View around Willy Field on a snowy day. photo J. Spergel

View around Willy Field on a snowy day. photo J. Spergel

Antarctica is a polar desert, but as mentioned before in this blog, it also experiences extreme weather. The weather patterns of the Ross Ice Shelf in particular have been a topic of research. The triangular Ross Ice Shelf is bordered by the Trans-Antarctic Mountains on one side, the high glaciers of Marie Byrd Land on the second and the Southern Ocean on the third. As a result, the ice shelf experiences a confluence of air masses. From the mountains and glaciers, cold, dense air sinks downslope and flows across the ice shelf in the form of katabatic wind. These winds join the clockwise-spinning air mass system coming from the Ross Sea. The high elevation of the mountains acts as a wind barrier and creates barrier winds parallel to the mountain ranges, which also add to the force of the wind vortex. As a result, the cyclonic Ross Ice Shelf Airstream (RAS) is a permanent, year-round part of the climate. Ross Island, where McMurdo Station is located, sits in the path of this wind and, like a rock in a stream, creates eddies on its leeward, i.e northward, side. Precipitation events occur when relatively warm, moist air is brought to Ross Island, and that moisture is released as snow.

 Atmosphere, 2006, Vol 111, Issue D12

A look at characteristics of the Ross Ice Shelf air stream from a 2006 study. Julian describes this cyclonic wind in the paragraph above.  Source: Journal of Geophysical Research: Atmosphere, 2006, Vol 111, Issue D12.

In other news, I was startled by this skua sitting in front of the dorm building, and now the rest of the Rosetta team has nicknamed me “Skua.”

A south polar skua appears very benign but these aggressive birds fly right at the heads of humans when they feel threatened. Photo (from a safe distance) J. Spergel

A south polar skua appears very benign but these aggressive birds are large and fly right at the heads of humans when they feel threatened. Photo (from a safe distance) J. Spergel

For more information about Rosetta-Ice, check out our website and the archive of this blog. Have questions about Rosetta-Ice or about living and working in Antarctica? Feel free to email your question to juliansantarctica@gmail.com, and I will try to answer it in the next blog entry!

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery.

Crevasses – Antarctic Ice Fractures

By Julian Spergel
Antarctic Ice showing crevassing along the edges of flow. photo J. Spergle

Antarctic Ice showing crevassing along the edges of flow. photo J. Spergel

As we prepare for our sixth flight of the season, I wanted to offer a glimpse of one of the types of glacial features that we are observing and studying as we map the Ross Ice Shelf: Crevasses. The word sends shivers down the spine of anyone whose job involves working on a glacier. These cracks through the glacier can be hundreds of feet deep and hidden beneath a thin layer of snow. They are incredibly treacherous and have claimed the lives of many polar explorers and scientists. They also appear quite frequently in our sensor data as we fly our survey flights for Rosetta-Ice.

The Icepod instrument, with the radar blades shown along the front edge, is being used by the Rosetta project to view through the ice to understand the features and thickness. Photo S. Howard

The Icepod instrument, with the radar blades shown along the front edge, is being used by the Rosetta project to view through the ice to understand the features and thickness. Photo S. Howard

Crevasses are fractures in a glacier caused by the stresses of movement. They are like the cracks in the surface of clay as one pulls it apart past the limits of elasticity. They most often occur where the flow of a glacier increases, like in a steep deepening valley, and are thus oriented perpendicular to direction of flow. Crevasses that lie in a cross direction are called ‘transverse crevasses.’ There are also longitudinal crevasses that form parallel to ice flow and at an angle to the valley walls. These form as the glacier widens and the ice is pulled apart. These cracks in the surface of the ice shelf are an easily identifiable marker of areas of high stress within the ice flow. Mapping where crevasses appear is equivalent to mapping where the ice tensional stresses are highest.

Several different types of crevassing are visible in this image including transverse crevasses, as ice flow from different areas collides. photo M. Wearing

Several different types of crevassing are visible in this image including transverse crevasses, as ice flow from different areas collides. photo M. Wearing

On an otherwise featureless ice shelf, crevasses show where the different ice flows merge as they flow towards the open sea. Fahnestock et al. (2000) mapped crevasses, rifts, and glacial stretch marks they call “flow lines” on the Ross Ice Shelf in order to study the flow of ice from different glacial source areas to the Ross Sea and how these patterns may have changed in the past thousand years. From their study of the surface features, they were able to draw lines across the Ross Ice Shelf and identify whether a region of ice shelf was flowing in over the Trans-Antarctic Mountains from East Antarctica, or from the rapidly flowing ice streams from West Antarctica, named from southwest to northeast Ice Streams A, B, C, D, and E. A piece of ice takes about one thousand years to travel from the back of the Ross Ice Shelf to the front, and from its surrounding area we can tell where the piece of ice originated.

Ice streams A, B, C, D and E flowing in from West Antarctica. Image from Rignot et al, 2011

Ice streams A, B, C, D and E flowing in from West Antarctica. Image from Rignot et al, 2011

The Rosetta ice-penetrating radar shows us crevasses deep with in the ice. These cracks formed on the surface and were carried along and buried by centuries of snow and glacial flow. In the radar image, buried crevasses appear as thin arches. As the radar beam penetrates through the snow and ice like ripples in a pond, bouncing off of surfaces of changing density, the sharp corner of a crevasse scatters the ripples. When the radar image is processed from the echoes of the broadcasted signal, this sharp point of scattering becomes an arch descending down from an otherwise flat surface.

Radar images of crevassing in the ice shelf showing the characteristic arch descending down from the flattened surface. Photo J. Spergle

Radar images of crevassing in the ice shelf showing the characteristic arch descending down from the flattened surface. Photo J. Spergle

What do these buried crevasses tell us? Like digging to the bottom of a stack of papers on a desk, these ancient crevasses tell us of past glacial events. Their burial depth divided by the local snow accumulation rates gives an estimate for the period of stagnation required to stop flow, fill and bury the crevasses to the observed depth. They indicate past flow conditions, or even the locations of abandoned shear margins, where there used to be a boundary between ice streams moving at differing speeds.

Close up view showing the strain in the ice as it is pulled by changes in flow speed. photo S. Howard

Close up view showing the strain in the ice as it is pulled by changes in flow speed. photo S. Howard

Lastly, crevasses are interesting because sometimes fascinating things fall into them. A few studies have shown that wind-blown meteorites get caught in snow-filled crevasses. Knowing where to look for rare meteorites is a huge help to our friends in the astro-geology community. Crevasses are also the places where meltwater drains down to the base of the ice. This affects the slipperiness of the glacier’s bed, and can speed up it flow. Meltwater flowing through crevasses also widens the crack, called hydrofracturing. This can further weaken the structural stability around the crevasse, priming the area for a later break. While Rosetta-Ice is not specifically looking for extraterrestrial rocks or draining water, we are on the lookout in our radar data for anything that can tell us about the history or current flow conditions of the Ross Ice Shelf.

Answers to a few of the questions asked by students at East Harlem School:

Is it possible for plants to grow in Antarctica?

Yes, a few. There’s a dozen native species that live on the Antarctic Peninsula, the thin peninsula of land that stretches north into relatively warmer parts of this continent. Everywhere else, only a few lichens, the crinkly stuff that grows on rocks and trees, survive.

How do you survive in the cold? What’s the hardest part about living/being in Antarctica?

With the right warm clothing and the right behavior, Antarctica’s conditions are very survivable. It’s very important to wear the right layers of clothes because you need to both stay warm, but also not let your sweat stay wet against your skin. I wear a thermal underwear layer that is warm and wicks sweat away. On top of that I’ll either wear a warm shirt or a thin sweater. On top of that, I wear a fleece or wool jacket, and then I wear my big red parka. Everyone has one and we call them our “Big Reds.” On my legs, I wear fleece pants and snowpants. I wear two layers of socks usually, and either my boots or the rubber boots that they gave us, called “Bunny Boots.” When I get too cold, I go inside, out of the wind, to warm up.

For me, the hardest part of living in Antarctica is the isolation. I personally use the internet a lot to connect to friends and family, but the combination of the slow internet connection and the time difference makes it difficult.

How has global warming affected how much ice will be there in 5 years?

We’re certain that the warming of ocean water is melting from underneath the floating ice shelves around Antarctica, and we predict that the warming atmosphere will lead to more melting and calving, but how much global warming-caused ice loss might there be within the next five years? There’s no way to know. What we still don’t know about how Antarctica’s climate works could fill a library. Weather over Antarctica is incredibly unpredictable, and we still cannot tell for sure how the multi-year climate cycles affect melting continent-wide. That question, how will global warming effect ice mass loss in Antarctica, is quite literally a multi-million dollar question. Thousands of scientists are studying every aspect of the Antarctic glacial system to get a sense of what is “natural” — what amounts of ice loss and gain are within the normal range of decades- or century-long cycles — and what can be interpreted as a result of human-caused climate change. Hopefully, Rosetta-Ice will yield a small piece of the puzzle.

For more information about Rosetta-Ice, check out our website and the archive of this blog. Have questions about Rosetta-Ice or about living and working in Antarctica? Feel free to email your question to juliansantarctica@gmail.com, and I will try to answer it in the next blog entry!

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery.

Flying is Easy, Just Think Happy Thoughts…

By Julian Spergel

As of my writing, we have completed three survey flights.  It feels good to finally be collecting data. The night shift, myself included, has spent the past two days checking the collected data for signs of any instrument breakage or recording errors.

 Susan HowardFlying past the Trans-Antarctic Mountains that line the East side of the Ross Shelf. Photo credit: Susan Howard

Although Peter Pan suggested ‘happy thoughts’ would get us airborne, in Antarctica we are still very much at the will of the weather. Yesterday evening’s flight was cancelled because of fog, and so this morning we wanted to get as much flying in as possible before the late afternoon fog rolled in. Although the morning shift had to wait a bit for the IcePod instruments and the plane to warm up before departing, they were able to complete two full survey lines before their afternoon return. It is early in the season and I haven’t been able to fly a mission yet myself, but I am eagerly waiting for my first opportunity.

 Alec LockettView out of the LC-130 during Monday afternoon’s flight. The aircraft wing is visible in the top left of the photo and the tiny grey spot in the snow is the shadow of the plane. Photo Credit: Alec Lockett

Our daily schedule is not the easiest when we fly. This is especially true for those who need to make decisions about our daily activities. Every day, from 4 to 4:30 AM, Kirsty Tinto, our chief scientist, checks to see if that morning’s flight is going ahead, next she checks in with the team ending their night shift for updates on instrument functioning. At 5 am, she and the day’s flight engineer meet with the weather operations and flight operations team to go over the day’s flight plan considering the weather forecast. The team has to be flexible when building a daily mission that works with the daily weather constraints.

 Susan Howard

Flight Engineer Chris Bertinato monitoring the airborne instruments inside the LC—130 cargo hold. Photo Credit: Susan Howard

Meanwhile, the gravity instrument operators, affectionately called the “graviteers,” go down to the airfield with the aircraft load-masters to oversee the loading of the gravimeter into the plane. Collecting data on minuscule changes to gravity requires that we know exactly where in the plane the instruments sit to calculate accelerations. Although it is tempting to leave the sensitive instruments on the plane overnight, the gravimeters must be kept warm at all times for peak functionality, as a result the gravimeters must be loaded and surveyed at the beginning of every day and unloaded at the end of the day. The plane is readied for take-off with a systems check and the flight crew and our project’s flight engineers prepare for flying.

The non-flight members of our team arrive to Williams Airfield soon after from our base at McMurdo camp. Every shift has an archivist, someone who copies the data from the various digital storage units carried in flight and then carefully transports them back to the tent. The data is transferred to the central computer, as well as to two backup hard drives for redundancy. At the end of the shift, there are nine hard drives and two USB sticks filled with data. The archivist also selects three to four five-minute segments of data for quality control, which we call “QCing”. The other QCers and I look through the segments from every data set for breaks in the data, for anomalies, and for particularly good or interesting segments. Arguably, the most important data set to check is our positioning-navigation-timing system. None of our data is useful if we cannot precisely place where in the world we were when we collected the data. Some of our instruments must also know precisely the angle and velocity of the plane in order to yield useful data. Once that is checked, we look at the data readouts.

Timelapse video of a few hours of night shift “QCing” Credit: Julian Spergel

If there’s anything surprising within the Ross Ice Shelf, we QCers might be the first ones to know…while it is fun to wonder what we could find, what do we actually see? In the radar data, we can see the surface and bed of the ice shelf and often we can see areas of buried crevasses. In the shallow ice radar, we can often see where different ice masses from geographically disparate glacial sources merge as they flow towards the ocean. From LiDar (Light Detection and Ranging), we can see very high detailed maps of the surface of the ice shelf, which can give us information about the flow of the ice and the changing surface climate conditions, i.e. wind and temperature. From gravity and magnetics readings, we can glean information about the size of the cavity under the ice shelf and the ocean bed beneath the water.

An aerial photo from our onboard camera of the edge between the ice and McMurdo Station. Photo by Susan Howard.

An aerial photo from our onboard camera of the edge between the ice and McMurdo Station. At the lower right you can see the circlar shape of a tank. Photo by Susan Howard.

Though we’ve just begun our survey flying, we’re excited to see what our instruments will show us about the Ross Ice Shelf. Weather permitting we will fly day and night this week pushing through being tired. Yes we are tired, and I know I am guilty of getting a little snippy, but we are down at the edge of the world for valuable scientific work. When I see the sun kiss the horizon, and watch the shadows lengthen for a moment and the snow become golden, I know that this experience will end up being incredible.

The mother crab-eater seal nursing her newborn pup. In the background, a skua hungrily eyes the afterbirth. South polar skua are aggressive seabirds,  scavengers and carrion eaters, readily scavenging any food source.

The mother crab-eater seal nursing her newborn pup. In the background, a skua hungrily eyes the afterbirth. South polar skua are aggressive seabirds, scavengers and carrion eaters, readily scavenging any food source. One of our ‘tough’ Alamo floats is named after a south polar skua. 

In non-science news, we saw the birth of a baby crabeater seal on Sunday. Everyone else on the team has named the newborn seal “Rosetta,” but in my mind, the seal’s name is “Boopy.”

For more information about Rosetta-Ice, check out our website and the archive of this blog. Have questions about Rosetta-Ice or about living and working in Antarctica? Feel free to email your question to juliansantarctica@gmail.com, and I will try to answer it in the next blog entry!

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery.

Settling in to McMurdo

The Rosetta team has been in Antarctica for a week now and we’re almost done with unpacking and testing all of our equipment. Our first survey flight of the season is scheduled for the end of the week.

An official 'proof'! My photo by the McMurdo sign is proof that we have really made it here after a lot of anticipation!!

An official ‘proof’! My photo by the McMurdo sign is proof that we have really made it here after a lot of anticipation!!

The first few days of our time in Antarctica was spent on safety training and ‘waiting on the weather’. Each step of our set-up process, like receiving cargo, installing electricity in our tent, unpacking our boxes, and building disassembled instruments, needs to wait for safe weather conditions, which in Antarctica is by no means guaranteed. Our workstation is a yellow Jamesway tent on the airfield named Williams Field. It is about a thirty minute drive from McMurdo Station, on a nearby section of the Ross Ice Shelf.

The landscape seems endless with ice shelf merging into white cloudy skies. The airplanes on the ice are close to the only relief.

The landscape seems endless with ice shelf merging into white cloudy skies. The airplanes on the ice are close to the only relief.

Even though we are within a short drive of McMurdo station, a small town with most of the safety and logistical equipment on the entire continent, we still need to prepare ourselves for sudden, extreme weather. Every time we leave the relative safety of McMurdo, we carry our Extreme Cold Weather equipment and our tent has emergency food and sleeping equipment. Driving onto the ice shelf is a surreal experience: the landscape is a nearly featureless white, flat expanse, with only tiny buildings and the black, slug-like shapes of lounging seals to break up the uniform whiteness. When there are low-lying clouds, the ice and the sky seem to meld into a single white area.

Unpacking our workspace in the Jamesway that will be our 'command center' during our work here.

Unpacking our workspace in the Jamesway that will be our ‘command center’ during our work here.

After two days of unpacking, our little tent is becoming very cozy. We have a line of tables for our computers and printer, a coffee machine and two gas heaters, a number of powerful external hard drive units called a Field Data Management System. Our scientific instruments are coming together, as well. To keep both ourselves and our electronics warm, we keep two heat-stoves running all the time. In preparation for our flights, we’ve split into two shifts, one in the day and one at night. Myself and six other people spent last weekend transitioning our daily schedules to sleeping during the day and being awake to work over the night. Due to the polar latitude, the sun never goes down, so the two shifts experience nearly identical levels of light. Yet my sense of time is very confused and I often forget what day of the week I am currently in.

Setting up our basestations to support our flight data.

Setting up our basestations to support our flight data.

Before we start recording and processing data from our first survey flights, we need to rebuild the instruments that were deconstructed for shipping, and calibrate them to make sure the data recorded is accurate. With round-the-clock activity, we have set up everything in only a few days. One of the needed activities was hanging the gravimeter onto a freely-suspended gimbal with bungee cords so that it is stabilized against the movement of the plane. Many of the components of our sensors are very delicate, but a large number of the external components are larger, easily adjusted, and could be found in a hardware store. Unlike other fields of science, polar fieldwork operates best when adjustments can be made while wearing heavy gloves.

Helping Tej to calibrate the IcePod on the C130 aircraft.

Helping Tej to calibrate the IcePod on the C130 aircraft.

Additional set up involves installing “base stations” to record a background level of magnetics and GPS information. A five minute walk across the ice from our tent, we have erected two yellow tripods and partially buried a small box of sensors. The instruments are powered by a small solar panel that we set up nearby. Each tripod needed to be secured against wind by tying the legs to bamboo poles we buried in the snow, a snow anchor. The snow on the ice shelf is incredibly dry and compact, so digging into it feels like digging through styrofoam. Filling in the holes with snow, stamping on it, and waiting only a few minutes allows the snow to harden to a strength similar to concrete.

Checking on the data output inside the plane and hoping for good weather for a flight!

Checking on the data output inside the plane and hoping for good weather for a flight!

Our first test flight is scheduled for the end of the week. We will fly one of our survey lines and make sure that the instruments’ readings are accurate so that on future flights we will know that the instruments are working properly. In addition we will be ensuring that each of the instruments functions by checking sections of the data after every flight. My assigned role once flights are running regularly is to analyze the ice-penetrating radar during the night shift.

For more information about Rosetta-Ice, check out our website and the archive of this blog. Have questions about Rosetta-Ice or about living and working in Antarctica? Feel free to email your question to juliansantarctica@gmail.com, and I will try to answer it in the next blog entry!

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery.

What’s a few days delay when preparing to visit a 33 million year old ice sheet?

The Rosetta team has been delayed in Christchurch, NZ since October 20th, and today, the 24th, we are all hoping very hard that today will be the day, that the weather will cooperate and the plane will have no issues so that we can get to McMurdo and start preparing to work. Morale is still high, we have all enjoyed exploring the local sights in Christchurch in the spare time we suddenly have. But it would be a huge inconvenience if we stay in Christchurch too long.

The Dumont d'Urville base where winds have been recorded at 199 mph. (photo credit Samuel Blanc)

The Dumont d’Urville base where winds have been recorded at 199 mph. (photo credit Samuel Blanc)

The dangers of Antarctic air travel cannot be emphasized enough. The weather is notoriously temperamental: winds as fast as 199 mph (327km/h) have been recorded at Dumont D’Urville station. Wind gets funneled down mountains and through fjord valleys, picking up speed. Blowing snow can limit visibility in a matter of seconds. Even crossing the Antarctic Circle is dangerous. Because there are no large landmasses to break the 40th line of latitude, ocean and wind currents can spin unimpeded around the continent. This is called the Antarctic Circumpolar Current. Sailors called the latitudes between New Zealand and Antarctica in order of southernness the Roaring Forties, the Furious Fifties, and the Shrieking Sixties.

Yet this inaccessibility is two-sided. The spinning wall of wind and water acts as a thermal insulator and keeps Antarctica chilly. The extreme environment, the massive ice sheet, and the unique ecosystems that attract the scientific community are all due to this forbidding climate system.

Antarctica is an isolated massive block of land primarily covered in ice. (photo M. Turrin)

Antarctica is an isolated massive block of land primarily covered in ice. (photo M. Turrin)

Was Antarctica always so inhospitably cold? Surprisingly, no. The development of the Antarctic ice sheets are relatively recent compared to the 4.5 billion year old history of the Earth. The precise mechanism that triggered Antarctic glaciation is still debated, but there is significant evidence that continental scale glaciation began around 33 million years ago, at the boundary of the Eocene and Oligocene. A combination of lowering CO2 levels and the formation of the Circumpolar Current when South American and Antarctica detached led to mountain glaciers in the Trans-Antarctic mountains to expand until the continent was covered [10.1038/nature01290]. Prior to this point, Antarctica is believed to have been forested, and dinosaur and early mammal fossils have been found around the continent.

We theorize that the crustal depression that has become the embayment holding the Ross Ice Shelf developed during the break-up of Gondwana.

We theorize that the crustal depression that has become the embayment holding the Ross Ice Shelf developed during the break-up of Gondwana.

The glacial and geological history of the Ross Embayment, the bay in which the Ross Ice Shelf sits, is one of Rosetta-Ice’s leading research questions. By making measurements of the seafloor, we hope to improve our understanding of the timing and distribution of sea-floor extension in the geological past. The tectonics of the region are still not well understood. We theorize that the crustal depression that has become the embayment developed during the break-up of Gondwana, the Mesozoic supercontinent composed of modern-day South America, Africa, Australia, Antarctica, India, and Arabia around 200 million years ago. As it pulled apart over millions of years, it stretched the crust in the region of the Ross Sea, thinning and depressing it. Over the past 33 million years, glacial ice has carved out landforms that now lie under the ice. During our work, we will use our instruments to look through the ice shelf and map those present day landforms. We would like to improve our knowledge of the history of the region, both of the geology and of the ice shelf. Why is this important? In addition to increasing our knowledge of the world’s geological history, the past of the Ross Sea can give us clues to its future. If we see evidence that the Ross Ice Shelf has broken up or disappeared in the past, we can say that the present-day ice shelf has the capacity to disappear in the future.

Stay tuned for updates on our Antarctic arrival and our scientific work. We’re standing by in Christchurch, parkas on, bags in hand, excited and ready to start another season of Antarctic science.

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Prof. Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery. He graduated with a BS in Geophysical Sciences with General Honors from the University of Chicago in 2016. He has been involved with a number of diverse projects and has been interested in polar studies since early in his career. His fieldwork has brought him north to the Svalbard Archipelago and south to McMurdo Station, Antarctica.

Learn more about previous years’ research, here.

For more on this project, please visit the project website: http://www.ldeo.columbia.edu/rosetta

Under the Sea Ice, Behold the Ancient Arctic Jellyfish

Arctic Sea Ice Ecology - Mon, 10/23/2017 - 14:20

The doings of creatures under the Arctic sea ice are many, but they are rarely observed by humans; it’s pretty hard to get under the ice to look. In recent years, marine biologist Andy Juhl and his colleagues have gotten around this problem by driving snowmobiles several miles from Point Barrow, Alaska, out onto the adjoining frozen Chukchi Sea, drilling holes in the four-foot-plus thick ice, and poking in a video camera attached to an small underwater vehicle.

Among the things that they have observed: sizable Chrysaora melanaster jellyfish floating by, trailing their foot-long-plus tentacles along the shallow bottom. Their presence came as a surprise: adult jellyfish, or medusae, are generally thought to live only a few months. Scientists had assumed that the species survived winter only in a life stage called polyps–formless masses that cling to rocks and release little baby medusae in the spring. In a scientific paper out this week, Juhl and colleagues say the videos indicate that the creatures in fact last through winter. They could even be several years old–the Methuselahs of medusae.

“One reason we were interested was, first of all, we saw them, and it was kind of weird,” said Juhl, a researcher at Columbia University’s Lamont-Doherty Earth Observatory. “The whole study is based on videos we made over several years.” Also, he says, the rich pollock fishery in the nearby Bering Sea is the engine for “everything fish”–fish sticks, fish paddies and other mystery-meat-type marine fast foods. But in some years, jellyfish numbers in the Bering Sea swell, and fishing nets can get seriously clogged–a problem that may crescendo over several years before dying back again. The study may reveal something about the jellyfish population dynamics that drive these cycles.

Juhl’s working hypothesis: cold winters, when sea ice is thick and long-lasting, are good for Chrysaora survival. He says the ice probably shields the medusae from turbulent winter storms, and the low water temperatures reduce their metabolism enough for them to subsist on relatively little food. “Life under sea ice is like living in a refrigerator–everything slows down,” he said. He said that jellyfish blooms may follow one or two years of heavy sea-ice cover because lots of adults survive.

Juhl points out that many other Arctic creatures also depend on sea ice. These range from lowly algae and bug-like amphipods that thrive on its underside to giant polar bears who roam around on top, waiting to pick off seals that emerge from breathing holes.

With Arctic climate warming and sea ice declining rapidly, what will happen to Chrysaora? Elsewhere in the world, including in the Mediterranean, other species of jellyfish are swarming and becoming pests, apparently in response to warmer waters, overfishing and coastal pollution. These forces are bad for other flora and fauna, but the resilient jellies often thrive, eventually taking over the ecosystem. In the far north, it could be the opposite; ice-loving jellies could decline if things warm up. So could the other, more iconic, creatures of the north that depend on sea ice. But at least jellyfish might not be clogging fishermen’s nets so much. “For most things, there are positives and negatives to climate change,” said Juhl.

One still unanswered question: Do these jellyfish sting? “I don’t know,” he said. “There aren’t that many people around there swimming to find out.”

Related: The Arctic’s Secret Garden

Final Stop – Antarctica’s Ross Ice Shelf

We have embarked! Our third Antarctic field season is underway putting us only 18 flights away from completing our mission to investigate the Ross Ice Shelf, the largest ice shelf in Antarctica. The Rosetta Ice Project is focused on developing a more complete understanding of the Ross Ice Shelf, the history of how it formed, what are the factors driving its current condition and what might control its future stability.

Drawing of the author Julian Spergel (by Freddy Bendekgey)

Drawing of the author Julian Spergel (by Freddy Bendekgey)

It is this writer’s first Antarctic field season, although traveling to Antarctica has been a life dream of mine since high school. I came to my obsession in an unusual way. In the summer of 2011, a heat wave knocked out the air conditioning units in my town. Sweltering, I took what little refuge there could be had in the public library. I had read somewhere that reading about cold places could cool you down, so for the next few weeks I pored over every account of polar exploration I could get my hands on. I was hooked, and especially hooked on Antarctica. It represented to me a place that remained mysterious and extreme, and whose challenging exploration by scientists represented the pinnacle of human ingenuity and international collaboration. I feel honored to be included in this field season, and to be documenting our findings and experiences for readers to learn from and enjoy. It is exhilarating to be on my way to achieving a personal goal of mine, though when I pictured myself as an Antarctic explorer as a teenager, I thought I would be taller!

An annotated version of the front of the Ross Ice Shelf from radar collected in this project. Note the shelf sits with most of the ice below the waterline.

An annotated radar image collected in the project showing the front of the Ross Ice Shelf. Note the shelf sits with most of the ice below the waterline.

To more thoroughly introduce the Rosetta-Ice project, it is a National Science Foundation funded multi-year collaboration between Lamont-Doherty Earth Observatory, Scripps Institute of Oceanography, Colorado College, and Earth & Space Research with critical support from the New York Air National Guard. Out goal is to complete a high-resolution survey of the Ross Ice Shelf in West Antarctica. The Ross Ice Shelf is a floating ice shelf roughly the size of Texas or of France that extends from the Trans-Antarctic Mountains into the Ross Sea, the portion of the Southern Ocean that faces New Zealand. Part of the ice shelf’s perimeter is grounded, at term that means frozen all the way down and connected at the base to the seafloor below. The rest of the shelf extends out floating as a thick apron of ice with about 10% of it visible above the ocean’s surface, the rest floating below the waterline. The ice shelf is up to 4000 thousand feet thick in its interior, and its margin with the sea is nine hundred feet thick in places. A large percentage of the surrounding ice streams in the Trans-Antarctic Mountains and West Antarctic Ice Sheet flow into the Ross Ice Shelf. As a result, the friction of the grounded portions affects the rate at which the ‘upstream’ ice flows and loses its mass through iceberg calving.

Lamont-Doherty Earth Observatory / Photo: Winnie Chu. The Rosetta project is focused on the Ross Ice Shelf in Antarctica. This shelf plays a critical role in stabilizing the Antarctic ice sheet, buttressing the ice that is constantly moving over the land surface. Studying how the ice, ocean and underlying land interact will inform us of potential change in the ice shelf from projected climate change. IcePod, shown along the front of the shelf, is a critical instrument in completing this project.

The IcePod flying over the the Ross Ice Shelf in Antarctica as part of the Rosetta project. The pod is lowered from an LC130 aircraft and holds a series of instruments that are critical to completing this project. (photo: Winnie Chu)

Rosetta-Ice is a detailed aerogeophysical survey, a series of survey flights collected using LC130s, rugged military cargo planes that fly equipment and support in the polar regions. The planes carries a variety of remote-sensing instrumentation inside an attached structure called IcePod, and flies a tight grid of observation tracts collecting data. The ultimate result will be a map of the Ross Ice Shelf with a spatial resolution of 10km (6mi). This will give us a comprehensive look into the ice shelf’s surface elevation, its internal glacial stratigraphy, its thickness, the ocean circulation beneath it, and the morphology of the bed beneath.

The research questions that the project seeks to answer concerns the ice shelf’s past and future. We want to understand how the ice shelf formed, and we are thus studying the internal structures within the ice and the bathymetry and geology of the bed underneath. Looking from the past to the future, we are interested in the stability of the floating ice. For this question, we are studying the circulation of ocean water underneath the ice, how the ocean interacts with the ice through melting, and where the ice shelf may be resting on the underlying bed. Each one of our instruments’ data gives us a piece of the answers. The Rosetta Stone, our project’s namesake, was inscribed with a message in multiple languages that could only be completely understood by comparing the three translations and interpreting them together. Likewise, we are interpreting our data from ice-penetrating radar, visual and infrared imagery, magnetic readings, and gravimeter information together to produce a complete picture of the Ross Ice Shelf’s dynamics.

McMurdo Base, Antarctica imaged with LiDAR. (processed by S. Starke)

McMurdo Base, Antarctica imaged with LiDAR. (processed by S. Starke)

In this coming week, we will be settling into McMurdo Station, the largest of Antarctica’s research stations, and setting up and calibrating our instruments so that we can begin this year’s flights as soon as we can. For more information about previous years’ work, please take a look at previous blog entries in the archives of this blog.

Author: Julian Spergel.  Julian will be blogging this season from Antarctica for the project.

For more on this project please go to the project website: http://www.ldeo.columbia.edu/res/pi/rosetta/

New Map of Alaska Seafloor Suggests High Tsunami Danger

Scientists probing under the seafloor off Alaska have mapped a geologic structure that they say signals potential for a major tsunami in an area that normally would be considered benign. They say the feature closely resembles one that produced the 2011 Tohoku tsunami off Japan, killing some 20,000 people and melting down three nuclear reactors. Such structures may lurk unrecognized in other areas of the world, say the scientists. The findings will be published tomorrow in the print edition of the journal Nature Geoscience.

The discovery “suggests this part of Alaska is particularly prone to tsunami generation,” said seismologist Anne Bécel of Columbia University’s Lamont-Doherty Earth Observatory, who led the study. “The possibility that such features are widespread is of global significance.” In addition to Alaska, she said, waves could hit more southerly North American coasts, Hawaii and other parts of the Pacific.

A tsunami can occur as ocean crust (brown area) dives under continental crust (orange), causing the ocean floor to suddenly moves. In one region off Alaska, researchers have found a large fault and other evidence indicating that the leading edge of the continental crust has split off, creating an area that can move more efficiently, and thus may be more tsunami-prone. (Anne Becel)

A tsunami can occur as ocean crust (brown area) dives under continental crust (orange), causing the ocean floor to suddenly move. In a region off Alaska, researchers have found a large fault and other evidence indicating that the leading edge of the continental crust has split off, creating a tsunami-prone area where the floor can move more efficiently. (Anne Becel)

Tsunamis can occur as giant plates of ocean crust dive under adjoining continental crust, a process called subduction. Some plates get stuck for decades or centuries and tension builds, until they suddenly slip by each other. This produces a big earthquake, and the ocean floor may jump up or down like a released spring. That motion transfers to the overlying water, creating a surface wave.

The 2011 Japan tsunami was a surprise, because it came partly on a “creeping” segment of seafloor, where the plates move steadily, releasing tension in frequent small quakes that should prevent a big one from building. But researchers are now recognizing it may not always work that way. Off Japan, part of the leading edge of the overriding continental plate had become somewhat detached from the main mass. When a relatively modest quake dislodged this detached wedge, it jumped, unleashing a wave that topped 130 feet in places. The telltale sign of danger, in retrospect: a fault in the seafloor that demarcated the detached section’s boundary landward of the “trench,” the zone where the two plates initially meet. The fault had been known to exist, but no one had understood what it meant.

The discovery was made near the end of the Alaska Peninsula. A tsunami from here could reach many land areas across the Pacific. (Anne Becel)

The discovery was made around the western end of the Alaska Peninsula and the eastern Aleutian Islands. (Anne Becel)

The researchers in the new study have now mapped a similar system in the Shumagin Gap, a creeping subduction zone near the end of the Alaska Peninsula some 600 miles from Anchorage. The segment is part of a subduction arc spanning the peninsula and the Aleutian Islands. Sailing on a specially equipped research vessel, the scientists used relatively new technology to penetrate deep into the seafloor with powerful sound pulses. By reading the echoes, they created CAT-scan-like maps of both the surface and what is underneath. The newly mapped fault lies between the trench and the coast, stretching perhaps 90 miles underwater more or less parallel to land. On the seafloor, it is marked by scarps about 15 feet high, indicating that the floor has dropped one side and risen on the other. The fault extends down more than 20 miles, all the way to where the two plates are moving against each other.

The team also dropped seismometers to the ocean floor. These revealed many small quakes typical of creeping plates originating in the area landward of the fault, but fewer on the seaward side. This suggests that while the deeper part of the subduction zone is indeed creeping along harmlessly, the outer, shallower parts are stuck against each other, and getting stretched. This may have created the fault, slowly tearing the region off the main mass; or the fault may be the remains of a past sudden movement. Either way, it signals danger, said coauthor Donna Shillington, a Lamont-Doherty seismologist.

Seafloor images were collected aboard the research vessel Marcus G. Langseth, the nation's main ship for seismic research. (Anne Becel)

Seafloor images were collected aboard the research vessel Marcus G. Langseth, the nation’s main ship for seismic research. (Courtesy Lamont-Doherty Earth Observatory)

“With that big fault there, that outer part of the plate could move independently and make a tsunami a lot more effective,” said Shillington. “You get a lot more vertical motion if the part that moves is close to the seafloor surface.” A rough analogy: imagine snapping off a small piece of a dinner plate, laying the two pieces together on a table and pounding the table from below; the smaller piece will probably jump higher than if the plate were whole, because there is less holding it down.

Other parts of the Aleutian subduction zone are already known to be dangerous. A 1946 quake and tsunami originating further west killed more than 160 people, most in Hawaii. In 1964, an offshore quake killed around 140 people with landslides and tsunamis, mainly in Alaska; 19 people died in Oregon and California, and waves were detected as far off as Papua New Guinea and even Antarctica. In July 2017, an offshore quake near the western tip of the Aleutians triggered a Pacific-wide tsunami warning, but luckily it produced just a six-inch local wave.

As for the Shumagin Gap, in 1788, Russian colonists then living on nearby Unga Island recorded a great quake and tsunami that wiped out coastal structures and killed many native Aleut people. The researchers say it may have originated at the Shumagin Gap, but there is no way to be sure. Rob Witter, a geologist with the U.S. Geological Survey (USGS), has scoured area coastlines for evidence of such a tsunami, but so far evidence has eluded him, he said. The potential danger “remains a puzzle here,” he said. “We know so little about the hazards of subduction zones. Every little bit of new information we can glean about how they work is valuable, including the findings in this new paper.”

In rural Alaska, infrastructure tends to cluster along the coast, making it vulnerable to tsunami. Waves generated here could reach to Hawaii and beyond. (Anne Becel)

In rural Alaska, infrastructure tends to cluster along the coast, making it vulnerable to tsunami. Here, a community on Kodiak Island. Waves generated in this region could reach to Hawaii and beyond. (Matthias Delescluse)

The authors say that apart from Japan, such a fault structure has been well documented only off Russia’s Kuril Islands, east of the Aleutians. But, Shillington said, “We don’t have images from many places. If we were to look around the world, we would probably see a lot more.” John Miller, a retired USGS scientist who has studied the Aleutians, said that his own work suggests other segments of the arc have other threatening features that resemble both those in the Shumagin and off Japan. “The dangers of areas like these are just now being widely recognized,” he said.

Lamont seismologists have been studying earthquakes in the Aleutians since the 1960s, but early studies were conducted mainly on land. In the 1980s, the USGS collected the same type of data used in the new study, but seismic equipment now able to produce far more detailed images deep under the sea floor made this latest discovery possible, said Bécel. She and others conducted the imaging survey aboard the Marcus G. Langseth, the United States’ flagship vessel for acoustic research. Owned by the U.S. National Science Foundation, it is operated by Lamont-Doherty on behalf the nation’s universities and other research institutions.

The other coauthors of the study are Spahr Webb, Mladen Nedimovic and Jiyao Li of Lamont-Doherty; Matthias Delecluse and Pierre-Henri Roche of France’s PSL Research University; Geoffrey Abers and Katie Keranen of Cornell University; Demian Saffer of Penn State; and Harold Kuehn of Canada’s Dalhousie University.

RELATED: Ancient Faults and Water Are Sparking Earthquakes Off Alaska

 

Eavesdropping on the Ocean’s Mighty Microorganisms

Mesoscope Hawaiian Islands - Thu, 07/13/2017 - 11:05

By Gwenn M. M. Hennon

Gwenn Hennon demonstrates experiment aboard the RV Kilo Moana

Gwenn Hennon demonstrates experiment aboard the RV Kilo Moana

The microscopic organisms that make up ocean ecosystems are invisible to the naked–eye, yet they are responsible for producing half the oxygen we breathe, and for sustaining all the world’s fisheries. Now, nearing the end of our three-week cruise of the North Pacific off Hawaii, we are working to understand how these tiny bacteria connect and communicate with one another.

We know bacteria have the ability to sense and respond to an unknown number of chemical signals, but we think it may be tens to hundreds. A few signals we know from lab experiments include quorum sensing molecules. Quorum sensing molecules are released by other bacteria to change the way cells behave when they have reached a sufficient density, or quorum. We know from previous work in the Dyhrman lab and the Van Mooy lab that quorum signaling is important in the bacteria communities that surround a particularly large and important
cyanobacterium, Trichodesmium. Tricho, as it is affectionately referred to, fixes large quantities of nitrogen fertilizer directly from nitrogen gas ( see my post: http://bit.ly/2udAf6F ). The bacteria surrounding Tricho, or its microbiome can greatly affect the rates of nitrogen fixation in ways we do not yet fully understand. Nitrogen fixation is one of the most important biochemical processes on earth and in the oceans. In ocean ecosystems, it enables microorganisms to grow even when other nutrients, such as nitrate and ammonium, are scarce.

We would like to understand which bacteria are actively recruited to colonize Tricho and other large cells, and how chemical signaling impacts this process. To do this, we created a trap for bacteria using new techniques pioneered by our collaborator Otto Cordero. From scratch, we made microscopic beads embedded with phytoplankton cell extract and magnetic particles that allow us to pull the beads out of solution, separating them from the seawater and free-living cells. Inside the bottle I’m holding (see photo) are thousands of these tiny beads mixed with ocean bacteria. Over the past few weeks, we have mixed natural bacteria found in the surface ocean with different mixtures of chemical signals and phytoplankton-flavored beads. After we take our samples back to the lab, we can use DNA sequencing as a kind of universal barcode to identify the bacteria caught in our trap.

I can’t wait to see what we will discover from these experiments, which give us new tools to eavesdrop on the conversation among marine bacteria. Understanding how bacteria communicate through signals is an important challenge for predicting the future of the ocean’s complex microbial ecosystem.

Deep thoughts from the Deep Blue Sea

Mesoscope Hawaiian Islands - Thu, 07/06/2017 - 11:36

By Gwenn M. M. Hennon

Post Doc Researcher Gwenn Hennon and colleagues pulling samples from the depths of the North Pacific

Gwenn Hennon and colleagues pulling samples from the depths of the North Pacific

As far as I can see from the ship to the horizon there is nothing but deep blue sea. Not a single ship has passed within sight since we left the north shore of Oahu. We are only a day’s steam away from the
Hawaiian Islands, yet in the vast Pacific Ocean we could go weeks without seeing another ship. The ship is nothing more than a tiny speck on a massive blue marble. This is one of the dwindling places on
earth where I feel truly alone with my thoughts.

The sea is a deep blue, so clear, that you might think it was devoid of life. We have seen only a few seabirds circling the ship and playing in the air currents we generate. We haven’t seen any whales or
sharks, only an occasional flying fish taking to the air in front of our bow wake. In this apparent desert, microbial life is king. Microbes here can persist off of little more than sunlight and gasses in the air. Marine microbes are expert recyclers, rapidly scavenging the precious little nitrogen and phosphorous fertilizers in the
surface ocean. Some of these microbes can even take nitrogen directly
from the air to use as fertilizer. Chemists figured out how to make
fertilizer from nitrogen gas by using incredible heat and pressure,
but these microbes can do it at ambient temperature and pressure.
Billions of years of evolution has given these tiny cells better
technology than the accumulated efforts of every chemist in the
history of humanity (I note with more than a little envy as a
chemistry major).

Very little gets wasted in this hyper-efficient ecosystem, but a
little waste is inevitable. Some of these microbes die, killed by
viruses or damaged by UV rays. Instead of being recycled or passed up
the food chain a tiny fraction of them will sink into the deep. A slow
rain of this waste falls from the surface ocean into the perpetually
dark “twilight zone” of ocean. Carried down with this waste is carbon,
nitrogen and phosphorous from the surface. At depth, these elements
are released by yet more microbes, munching away on the pieces of the
dead and dying cells. About three miles directly below us on the sea
floor a very small fraction of this waste will be buried in sediments
and preserved for millions of years. In the enormous warehouse of
sediment cores drilled from the ocean floor in Lamont-Doherty Earth
Observatory, I have seen first-hand how the remains of ancient
microbes allow researchers to look into the deep past.

In the next few days, the MESOSCOPE team will set traps to collect
freshly sinking material. Our estimates of how much carbon and other
elements sink out of the surface ocean every year are still very
uncertain. We do not yet understand the factors that allow particles
to sink out and escape the gauntlet of scavengers. Carbon carried to
depths by dead microbes is estimated to be on the same order of
magnitude as the yearly global emissions from fossil fuel burning. So
far, the ocean has absorbed about half of the carbon dioxide emitted
into the atmosphere from human activity, but we can’t yet predict how
the equation might change in the future.

Standing on the back deck of the Kilo Moana, the deep blue sea makes
me feel both insignificantly small and reminds me of the power of
microbial life to shape our planet. In a million years how many atoms
of carbon from my exhaled breath or from the smoke stack of the Kilo
Moana will be trapped in deep sea sediments? Not sure I could
calculate that yet… but give me some time.

Setting Off to Explore the Depths

Mesoscope Hawaiian Islands - Thu, 06/29/2017 - 10:47

By Gwenn Hennon and Matthew Harke

Loading the R/V Kilo Moana

Loading the R/V Kilo Moana

For the past few days, we have been loading the gear and setting up our lab on the R/V Kilo Moana. We have to secure everything down to the benches to prevent equipment from falling and being damaged in rough seas.

Yesterday, we set sail at 8am, rounded the Island of O’ahu, and headed north into the blue waters of the North Pacific Subtropical Gyre. We are currently in transit, but this gives us time to test equipment and make sure everything is in order by the time we reach our first station. It also gives us time to help with the many shipboard operations. After a hearty breakfast of eggs, bacon, tater tots, and coffee, we had the opportunity to help deploy a “towfish” from a boom extending out 15 meters off the starboard side of the boat. Since this was the first deployment of its kind on this vessel, there were a lot of hands to help. Matt is the guy in the blue hard hat.

A towfish is a device which looks like a torpedo. The towfish is tethered to the boat and lowered into the water with the boom. It then “swims” through the water while the ship is under way, allowing us to take continuous samples. The team is trying to collect trace metal samples, and so they attached a trace metal-clean hose to the towfish to pump water as far from the ship as possible.

towfishOne difficulty with working on a large steel ship is that it “leaks” a lot of iron (as well as other metals) into the water. If you care about measuring iron levels in the water, you need to find a way to get away from the ship, and this method seems to do the trick. After a successful deployment and refueling at lunch, we also helped deploy and recover an underway CTD off the stern of the vessel. CTD stands for conductivity, temperature, and depth. This device allows us to profile the eddy as we transit across, giving us an in-depth look at the physical structure of the eddy. This will allow us to more accurately target water features when we stop to collect water later on. Each deployment lasts around 15 minutes and involves dropping the underway CTD off the back of the boat, letting it sink to 300 meters, reeling it in, resetting it, and then redeploying it. All of this is done while the ship is moving at about 8 knots. This will go on for the next day or so, as it takes a few days to traverse an eddy.

Racing time to Explore Ocean Ecosystems: A Mother’s Work

Mesoscope Hawaiian Islands - Thu, 06/22/2017 - 11:42

By Gwenn Hennon, PhD

Gwen HennonAs I kissed my 1-year-old son goodbye this morning at daycare it seemed like any other day. Yet as I dropped him off, I knew that I wouldn’t see him again for almost four weeks. I will be returning just in time for his second birthday. My heart aches knowing that he will likely be calling for me as my husband gets him ready for bed tonight, not understanding why I can’t be there to read him a story and kiss him goodnight.

Don’t get me wrong, I love my job! I love that as a biological oceanographer I get to go to sea off the Hawaiian Islands to study how ocean life is shaped by swirling 60-mile-wide currents. The microscopic organisms that make up ocean ecosystems are invisible to the naked-eye, yet they are responsible for producing half the oxygen we breathe and sustaining all the world’s fisheries.

Scientists like myself are in a race against time to understand the fundamental drivers of ocean ecosystems before climate change pushes them towards a new unknown state. State-of-the-art models predict that warming, ocean acidification, and changes in ocean currents predicted for the year 2100 will have big impacts on the structure of the microbial ecosystem. These changes have large potential consequences for carbon sequestration and the rate of climate change, as well as the security of the world’s food supply. 2100 may seem like a long time off, but it’s likely that my son will be alive to see it. When he is 85 years old, what will he make of the world we have left for him? Did we accurately predict changes to the ocean ecosystem? Did we do enough to avert an ecological disaster?

Because no one has invented a time machine, we have to make do with our current best guesses. Unfortunately, our picture of the ocean ecosystem is far from complete, making it difficult to predict the future.  As I board my flight for Honolulu, I’m grateful for the opportunity to fit a few more puzzle pieces into the big picture of how the ocean ecosystem functions. Every scientist and crew member participating in this research cruise will make sacrifices, leaving behind family and friends, and working round the clock in an effort to gather new data to understand ocean processes. Wish us luck for a successful trip!

Could Climate Change Shut Down the Gulf Stream?

Greenland Thaw: Measuring Change - Tue, 06/06/2017 - 13:28
The Gulf Stream

The Gulf Stream

The 2004 disaster movie “The Day After Tomorrow” depicted the cataclysmic effects—superstorms, tornadoes and deep freezes— resulting from the impacts of climate change. In the movie, global warming had accelerated the melting of polar ice, which disrupted circulation in the North Atlantic Ocean, triggering violent changes in the weather. Scientists pooh-poohed the dire scenarios in the movie, but affirmed that climate change could indeed affect ocean circulation—could it shut down the Gulf Stream?

The many ocean currents and wind systems that move heat from the equator northwards towards the poles then transport the cold water back towards the equator make up the thermohaline circulation. (Thermo refers to temperature while haline denotes salt content; both factors determine the density of ocean waters.) It is also called the Great Ocean Conveyor, a term coined in 1987 by Wallace Broecker, Newberry Professor of Geology in the Department of Earth and Environmental Sciences at Columbia University and a scientist at Lamont-Doherty Earth Observatory. Broecker theorized that changes in the thermohaline circulation triggered dramatic changes in the North Atlantic during the last ice age.

Thermohaline_Circulation_2

In the high latitudes, the cold water on the surface of the ocean gets saltier as some water evaporates and/or salt is ejected in the forming of sea ice. Because saltier colder water is denser and thus heavier, it drops deep into the ocean and moves along the depths until it can rise to the surface near the equator, usually in the Pacific and Indian Oceans. Heat from the sun then warms the cold water at the surface, and evaporation leaves the water saltier. The warm salty water is then carried northwards; it joins the Gulf Stream, a large powerful ocean current that is also driven by winds. The warm salty water travels up the U.S. east coast, then crosses into the North Atlantic region where it releases heat and warms Western Europe. Once the water releases its heat and reaches the North Atlantic, it becomes very cold and dense again, and sinks to the deep ocean. The cycle continues. The thermohaline circulation plays a key role in determining the climate of different regions of the earth.

The Atlantic Meridional Overturning Circulation, part of the thermohaline circulation which includes the Gulf Stream, is the ocean circulation system that carries heat north from the tropics and Southern Hemisphere until it loses it in the northern North Atlantic, Nordic and Labrador Seas, which leads to the deep sinking of the colder waters.

Greenland melting in 2012

Greenland melting in 2012

Because the thermohaline circulation is mainly driven by differences in the water’s density, it depends upon the cold dense waters that sink into the deep oceans. Global warming can affect this by warming surface waters and melting ice that adds fresh water to the circulation, making the waters less saline; this freshening of the water can prevent the cold waters from sinking and thus alter ocean currents.

As the planet warms, more and more fresh water is entering the system. In 2016, the extent of Greenland’s melting sea ice set a new record low. That May, the Arctic lost about 23,600 square miles of ice daily, compared to the long-term average loss of 18,000 square miles per day. A study by Marco Tedesco, a research professor at Lamont-Doherty specializing in Greenland, and colleagues suggested that a reduction in the temperature difference between the polar and temperate regions (the Arctic is warming twice as fast as the rest of the planet) pulled the jet stream air currents northwards. The warm moist air it carried hovered over Greenland, causing the record melting.

So far this year, Tedesco said, “The melting in Greenland is within the mean, but it’s still above the average of what was happening 20 years ago…The snow melt from Siberia has also been melting sooner, there’s been more fresh water from Greenland, there’s more fresh water from sea ice in the Arctic Ocean and more fresh water from North Canada which has been melting at an increasing rate. All these factors are pointing in the direction of increasing the freshwater discharge in the North Atlantic section of the Arctic. It’s very likely going to have an impact.”

Greenland's ice cap is darkening

Greenland’s ice cap is darkening

In addition to warming temperatures accelerating Greenland’s melting, the snow and ice are being darkened by black carbon,  (reducing their reflectivity and warming the snow), and wind-blown algae and bacteria that are growing in holes in the ice. “More biological activity implies darker surfaces which in turn implies more melting,” said Tedesco. “But I think there is still not enough knowledge to properly project [what the impacts could be]…We know there is an impact and it’s important to quantify that impact because we need to know what the processes that we need to consider are to do proper projections.”

A 2015 study hypothesized that fresh water, which increased in the northern Atlantic by more than 4,500 cubic miles (19,000 km3) between 1961 and 1995, weakened the deep water formation of the Atlantic Meridional Overturning Circulation, particularly after 1975. The circulation has slowed between 15 and 20 percent in the 20th century, an anomaly unprecedented over the last millennium, which suggests it is not due to natural variability. The scientists hypothesized that this could explain why, in 2014, a specific patch in the middle of the North Atlantic was the coldest on record since 1880 while global temperatures everywhere else were increasing. The study suggested that the unusual cooling of this region could be due to a weakening of the global conveyor that is already occurring. (It seems to have made a partial recovery since 1990.)

Michael Mann, Distinguished Professor of Atmospheric Science at Penn State University, one of the study’s authors, noted that if the Atlantic Meridional Overturning Circulation were to totally collapse over the next few decades, it would change ocean circulation patterns, influence the food chain, and negatively impact fish populations. We would not return to very cold conditions, however, because the oceans have taken up so much heat.

Another 2015 study that modeled a hypothetical slowdown or collapse of the Atlantic Meridional Overturning Circulation concluded that a collapse could result in widespread cooling throughout the North Atlantic and Europe (though this would be somewhat mitigated by global warming), increased sea ice in the North Atlantic, changes in tropical precipitation patterns, stronger North Atlantic storms, reduced precipitation and river flow as well as reduced crop productivity in Europe. These effects would impact many regions around the globe.

Sea levels are rising at Assateague

Sea levels are rising fast at Assateague in MD and VA.

Sea levels would be affected as well. Currently sea levels are lower on the U.S. east coast because waters east of the Gulf Stream, closer to Europe, are warmer and expand, so sea levels there are higher. If the Gulf Stream is weakened, the temperature differential between the two sides is reduced, so sea levels will rise on the west of the Gulf Stream along the U.S. east coast and the North Atlantic. In fact, sea levels along the coast and the Gulf of Mexico are rising faster than in any other part of the U.S, and some data suggests that it is because the Gulf Stream has already begun to slow down. Other research attributed a jump in sea level rise from New York to Newfoundland from 2009 to 2010 to the Atlantic Meridional Overturning Circulation slowing down 30 percent in the same period, as well as unusual wind currents that pushed ocean waters towards the coast.

Not all scientists agree that the Atlantic Meridional Overturning Circulation is slowing or that if it is, the phenomenon is caused by human induced global warming. A 2016 study suggested that while a great deal of fresh water has been discharged from Greenland, it’s difficult to track what happens to it because of eddies and currents. This research concluded that most of Greenland’s meltwater moves southward, and what remains of the fresh water is not enough to affect the Atlantic Meridional Overturning Circulation. The scientists did acknowledge, however, that the ongoing rapid melting of Greenland and increases of fresh water could eventually affect it.

The bottom line is that the thermohaline circulation is a very complex system and scientists do not yet understand all the variables involved in how it functions. There is an ongoing debate about why the Atlantic Meridional Overturning Circulation has weakened and how much is due to the effects of human activity on the climate.

Earth during the Ice Age

Earth during the Ice Age

In the Earth’s past, scientists have seen evidence of large inputs of fresh water into the North Atlantic from melting glaciers and ice caps as well as changes in the thermohaline circulation during transitions in and out of glacial periods. Global warming could potentially cause a thermohaline circulation shutdown and subsequent regional cooling, but because Earth will continue to warm as a result of greenhouse gas emissions, it would not produce another Ice Age. If the thermohaline circulation shut down, cooling would likely occur only in regions that are currently warmed by the ocean conveyor. And even if the thermohaline circulation did shut down, winds would still likely drive the Gulf Stream; however, there would be less warm water from the tropics and the Gulf Stream could become cooler and not reach as far north.

The 5th assessment report of the Intergovernmental Panel on Climate Change says, “…the Atlantic Meridional Overturning Circulation is generally projected to weaken over the next century in response to increase in atmospheric greenhouse gas emissions…. Overall, it is likely that there will be some decline in the AMOC by 2050, but decades during which the AMOC increases are also to be expected.”

According to Broecker, although reorganizations of ocean circulation are at the core of what happened in the past, we cannot say what the likelihood is that warming due to greenhouse gases will trigger yet another large and abrupt change. But if it were to occur, the consequences would be far less severe since, in the past, large existing expanses of sea ice were significant players in cooling the planet. “A conveyor shutdown is not likely,” said Broecker. “But if it happened, it would be ten times less dramatic and important than what happened during the glacial period when it caused a 10˚C temperature change.”

“We are monitoring the strength of deep water going south,” he said. “And we are finding large seasonal changes and interannual changes…It’s a complicated system and we can’t make any predictions.”

“The important thing is to understand better what is happening, by when it’s happening and what the potential implications will be,” said Tedesco. “Our priority is to better estimate the behavior of the Arctic and its connections to the temperate part of the planet in the short and long term…The question is not if things are going to change, the thing is how fast and when are they going to change, and what are the changes we’re going to see. There are changes at the local scale that are occurring on a much shorter time frame, and changes in the long-term that could include the shutdown of the ocean circulation. We need to understand the processes to properly build the models [to make projections].”

Lamont-Doherty’s Arctic Switchyard Project explores the circulation, variability, and driving mechanisms of the fresh water arriving in the Arctic Ocean, north of the eastern Canadian Archipelago and Greenland.

 

Sampling on the Ganges and Brahmaputra Rivers

Geohazards in Bangladesh - Sat, 02/04/2017 - 21:51
Chris smiling broadly as he and Humayun buy 11 lbs of Jordibaja, a local Kushtia snack food from the most famous bakery that makes it.

Chris smiling broadly as he and Humayun buy 11 lbs of Jordibaja, a local Kushtia snack food from the most famous bakery that makes it.

From Khulna in the SW, we are heading to Rajshahi on the Ganges River, but first we are stopping at Kushtia, Humayun’s home town. Because the road on the more direct route is supposed to have bad road conditions, we took a longer route, way longer. It wiped out any chance to get to Rajshahi in time for some fieldwork, but it did my districts (states) of Bangladesh visited to 40 out of 64. After many hours on the road, we reached Kushtia and out goal – jordibaja, a fried noodle snack that is only available here. Chris bought ten 500 gram bags, about 11 lbs, at the bakery that makes

Liz in Rajshahi walking back to our group protected by two policewoman that were part of our escort during a quick visit back to our van.

Liz in Rajshahi walking back to our group protected by two policewoman that were part of our escort during a quick visit back to our van.

the best, of course. We then had a late lunch and continued to Rajshahi where we were once again joined by a police escort. Different teams stayed with us until we left the area. After finding our hotel, we all had our first hot water shower since we left Dhaka. Living on boats is great, except for the complete lack of hot water. Once cleaned up, we went to Humayun’s sister for a delicious dinner. After dinner, the commissioner of police, a former student of Humayun’s stopped by. He suggested we visit some of the chars (sandy river islands) close to Rajshahi rather than the places we went

Our police escort watches Chris and Dan measuring spectra on a char (sandy river island) to compare with satellite measurements.

Our police escort watches Chris and Dan measuring spectra on a char (sandy river island) to compare with satellite measurements.

to other years, an hour or more drive away. Chris and Dan checked their satellite images and found that the nearby chars would work, probably dsaving 2-3 hrs of driving.

The next morning, we headed off with out new escort, that included two policewoman. However, that had to switch off when we crossed from one precinct to another. Renting a country boat we crossed the Ganges to the chars. While Dan and Chris (with Humayun) made salinity, moisture and spectroscopic measurements, Liz and I

Dan measures the water content of a small area of quicksand we found while Liz is being sucked in as she explores it.

Dan measures the water content of a small area of quicksand we found while Liz is being sucked in as she explores it.

scouted for the proper sediment samples for her OSL needs. After wandering about the island we found what she wanted and collected a sample. Until now, her studies of the delta did not have any samples from the Ganges itself. For Dan and Chris to get the observations they wanted, we visited several chars before ending up back at the first one for them to study the transition from sandy sediments to rice fields. As soon as the chars have deposits of the right kind of sediments, people start planting crops. If the char continues

Digging out our OSL dating sample of silt on the Ganges. The tape wrapped PVC pipe had been hammered entirely into the outcrop. The sample inside must not be exposed to light or it will be ruined.

Digging out our OSL dating sample of silt on the Ganges. The tape wrapped PVC pipe had been hammered entirely into the outcrop. The sample inside must not be exposed to light or it will be ruined.

to grow and stabilize, they will move there as well. They are great places to live 9 months of the year, but a struggle during the high water of the monsoon season. The islands with migrate, eroding from one side while sediment deposits on the other. The char people have to move frequently as the chars move out from under their homes. Liz and I wandered off and found another place to sample. Now she have both a sand and a silt samples from the Ganges. It only took a few hours to accomplish the more specific tasks of this field program. When we first started visiting chars 12 years ago, we explored then from the morning

Chris and Dan discussing notes on locations to visit based on recent satellite images and entering them into the GPS.

Chris and Dan discussing notes on locations to visit based on recent satellite images and entering them into the GPS.

until dusk. We needed to see and explore all aspects of this new environment for us. Now, we are building on our work with much more focused activities.

Off the river by early afternoon, we drove across country to Bogra near the Jamuna River, as this part of the Brahmaputra is known. We were able to arrive around sunset, avoiding the sometimes frightening driving in the dark. For old times sake, we skipped the new hotel that was booked and stayed at the colorful Parjartan Hotel that we first used

Chris, Dan, and Bulbul, our driver, walking down the embankment at Sirajganj. During the summer, the water level will reach the top of the embankment as the river flow increases by a factor of 10 or more.

Chris, Dan, and Bulbul, our driver, walking down the embankment at Sirajganj. During the summer, the water level will reach the top of the embankment as the river flow increases by a factor of 10 or more.

in 2005. It is literally painted the colors of the rainbow, as well as having more character, even if everything is not quite working. This was the hotel where my room once had electric outlets of 4 different shapes, requiring every adapter I had to recharge my equipment. Now I always bring an outlet strip so I only need one adapter.

We had planned to go north to Gaibandha, but a new satellite overpass showed that we could get all the data we needed farther south at Sirajganj. We could cut out a day. As it turns out, this was fortuitious. I have a family

Humayun walks to the country boat we rented at Sirajganj to bring us across the river to the chars.

Humayun walks to the country boat we rented at Sirajganj to bring us across the river to the chars.

emergency and have to return to the U.S. From Sirajganj we could return to Dhaka, rather than stay at Tangail. Chris and the others can do the rest of the field work as day trips from Dhaka. It is more driving for them, but will enable be to catch the evening flight back to the U.S. We packed up and headed to the embankment at Sirajganj, which protects the city from the shifts in the Jamuna River. We walked down the embankment (the river level is about 7 m or 23 feet higher during the summer monsoon season). We headed for a large char that

Liz examines an outcrop on the large char across from Sirajganj while looking for appropriate sediments to sample. Wherever the conditions are right, the chars are planted with crops while the bare sand remains exposed in the younger parts of the char.

Liz examines an outcrop on the large char across from Sirajganj while looking for appropriate sediments to sample. Wherever the conditions are right, the chars are planted with crops while the bare sand remains exposed in the younger parts of the char.

we first visited in 2005. It has grown and become attached to other chars. It also has much more agriculture, they are growing rice, peanuts, lentils, corn and more. The complex history of changes in the char provides lots of different sediment types for Chris and Dan and plent of cut bank surfaces for Liz to get a good silt sample. A few hours of exploring, sampling, measuring and we were done. Since it is Friday, the Muslim holy day and the weekend here, traffic is light until we reach Dhaka. Near the university and our hotel, the streets are packed with people and rickshaws. Still we manage to get to the university to drop off equipment and for me to get 7

Liz measures the position of the hammered in sampling tube before we dig out and collect our last sample, a silt from the Jamuna (Brahmaputra) River.

Liz measures the position of the hammered in sampling tube before we dig out and collect our last sample, a silt from the Jamuna (Brahmaputra) River.

GPS receivers that finally have to be returned to UNAVCO after 10 years. This is the last of the 11 we were lent in 2007 by them. They provide geodetic data and services for NSF and allowed us multiple extensions that enabled us to get this much needed data for so long. It is the basis for our paper on the potential earthquake hazard in Bangladesh as we can see the slow motion of the surface (0-17 mm/y) that indicates the buildup of strain in the earth. Then back to our hotel to meet Dhiman and have a final dinner together before an Uber takes me to the airport. It is sad to leave early, but I

A local farmer shows Liz the peanuts he is growing on the char (behind them). Peanuts and lentils are common winter, or rabi, crops on the higher, drier parts of the char. The freshest peanuts we ever ate.

A local farmer shows Liz the peanuts he is growing on the char (behind them). Peanuts and lentils are common winter, or rabi, crops on the higher, drier parts of the char. The freshest peanuts we ever ate.

am needed at home and they can carry on without me for the last few days. They will visit the confluence of the Ganges and Brahmaputra Rivers, and the Padma, as the combined river is called. For me, my critical goals for this trip were accomplished.

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