While installing our seismic network in Malawi, we interacted with everyone from scientists to schoolteachers, and journalists to villagers. The opportunity to provide information and education to Malawians has been the most rewarding aspect of our effort. We trained local scientists and technicians on seismic equipment and data analysis, and educated the public on earthquakes and earthquake monitoring both in person and via media interviews. The Malawi Geological Survey Department (MGSD) prompted our visit by requesting assistance in monitoring aftershocks, and we hope that this temporary seismic deployment will empower them to obtain resources and training for a permanent seismic network.
Because we deployed our seismic stations near schools, clinics and other centers of village life, we met a wide spectrum of Malawians. Everyone we spoke with expressed interest in our undertaking and wanted to know more about the chindindindis (earthquakes in Tumbuka). In the village of Mpata, 5 miles west of Karonga, a crowd gathered around a laptop balanced on the hood of our 4×4 as Jim showed them aftershocks in newly downloaded data; the audience peppered him with pertinent questions about the East African Rift and earthquakes beneath Lake Malawi. Curious policeman looked on as I retrieved seismic records from a station positioned near a checkpoint ~10 miles north of Karonga, inquiring when and where the next earthquake would occur. Science teachers in Mlare helped us install a station near their school and received an impromptu lesson in plate tectonics and seismology.
Journalists from newspapers, radio stations and national TV programs also interviewed us during our visit, which allowed us to communicate with a larger audience about possible causes of the earthquakes and the benefits of monitoring them.
We worked side by side with scientists and technicians from the MGSD every day of our visit. They taught us local geology, local customs, and local language, and made our joint endeavor possible by facilitating contacts with national and regional officials. In return, we brought them seismic monitoring equipment, helped them deploy it, and taught them new techniques for analyzing the resulting data. Although the MGSD is charged with monitoring earthquakes within the Malawi rift valley, their efforts are severely hampered by paucity of data and lack of training. Only two seismic stations exist in Malawi (provided by Africa Array), and university-level courses in seismology are almost non-existent. The data and training of MGSD employees provided by our temporary deployment following the Karonga earthquakes will help mitigate these problems in the short term; we hope that this experience will equip the MGSD with the ammunition to argue for more national and international resources for seismic monitoring in Malawi over the longer term.
Mike and I head out today for Cerro Gorra, leaving Jay and Barbara at Lago Cardiel to finish the stratigraphy. What wonderful people; I am so grateful to have had the opportunity to do field work with them.
We drive to Lago Argentino, where Mike is meeting a new research team for a separate project. We have just enough time to stop at the Perito Moreno glacier in Los Glaciares National Park. The only glaciers I’ve seen before have been quiet and still but this one cracks and grumbles as we watch. The sound of breaking ice echoes through the valley; the noise seems outsized for the quantity of ice.
I still can’t imagine how ice like this once coursed through valleys to blanket huge parts of Patagonia. The glacier I’m looking at is enormous; a tourist boat near its base looks like a wind-up-toy. I’m trying to comprehend how much snow would be needed to make this glacier grow thicker and hundreds of miles longer. It’s a lot easier to understand how a glacier can grind up mountains to make dust.
Anyway, I’m back in Rio Gallegos safe and sound. Tomorrow I return our rental car and get back on a plane for Buenos Aires and then New York. Mike has our samples in a bag; he’s going to FedEx them back to the States in a cardboard box. Hopefully they’ll arrive intact. This has been an incredible field experience, and I’m incredibly thankful to Gisela and Mike for arranging the trip. I hope we get some good data!
Last night I made dinner. I’ve never cooked over an open fire—only on a tiny gas-powered stove on backpacking trips–but Jay and Barbara have been teaching me how. Dinner was edible. Jay built the fire last night, but tonight I’m hoping to do the whole thing start to finish. Wish me luck.
We left Cerro Gorra this morning after spending all of yesterday taking dust samples and studying the Cerro’s stratigraphy. We were looking for ancient dust stuck in lake sediments. Dust floating in the air falls onto the lake and sinks to the bottom, where it gets trapped in mud. Normally, we’d have to drill a core into the bottom of the lake to get at these sediments, but drilling takes time and money. Lucky for us, the local climate and geology let us sample these sediments without drilling.
The lake’s water level has fallen over the last 20,000 years, leaving its ancient bottom sediments exposed. When a stream cuts through the layers of sediment, you can see the whole depositional record of the lake. We stood in the stream bed looking at its banks, and the layers of sediment deposited as the lake waxed and waned.
“Look,” says Jay, pointing to cobble layer between the sediments, “There’s an old shoreline with shells in it!” A few inches above the cobble layer was a layer of organic material. We hacked out chunks of sediment from those layers with our trowels and stuck them in Ziploc bags. Jay added shells from the layers to date their age. Once the shells are dated, we can estimate the age of the sediments.
Now we continue to the other side of the lake, stopping at Rio Bayo, on the north shore. We’re just about to move on to another area with better stratigraphy when we spot shells with brownish-green markings, different from the white shells we’ve been seeing for days. Finding pigmented shells comes as a surprise, though it shouldn’t since not all shells are bleached white once the organism inside dies.
Surprise number two: we find another kind of shell, fragile and scallop-like, the size of quinoa grains that break as soon as you touch them. Surprise number three: while collecting pigmented shells, we realize there are actually two different types. They look similar until you notice the wider aperture and tighter whorls of one species, plus other variations in shape. Once we see the difference, though, it’s hard not to hit yourself over the head and say “Stupid! Of course they’re different!”
This trip reminds me how easy it is to see what you want to see. Looking more closely at a shell or shoreline is how science advances, but learning to be this observant is incredibly difficult.
Reconstructing a shoreline history takes skill. Today we’re using altimeters to establish the elevation of Lago Cardiel’s former shorelines. We also continue to look for shells to help us date the lake’s past shorelines, a task that requires strong powers of observation.
In one short stretch there might be a dime-sized snail shell almost indistinguishable from the millions of white, rounded pebbles on this ancient beach. A few meters away, we might have to readjust our eyes to search for tufa, or smoothed glass fragments (people left bottles on the shore, which wore down like sea glass). Most often, we don’t know what we’re looking for, so we shuffle around looking staring at our feet as if trying to find a lost contact lens.
Barbara, Jay’s wife, is a master at finding stuff. She spotted a piece of nacre—the shiny part of an oyster shell–about the size of a quarter. I have no idea how she picked it out from the grayish-blue rocks around it. The fragment must have come from a pretty big oyster. Could giant freshwater oysters once have lived here?
As the hunt continues, Mike finds an oyster chunk as long as a stick of gum, and I discover a saucer-sized fragment, and another, the size of my palm.
What are these things? I picture a filter feeder big enough to eat a flamingo. With each fragment we find, it becomes obvious that these oysters probably originated from the sea. Jay says we’re on the edge of a drainage delta, so these oyster fragments may have been carried downstream from their fossil beds and deposited here.
These bivalves also appear to be ancient. Mike remembers finding similar oysters several years ago near a rock outcropping at least as old as the Miocene, the geological period that spanned from 23 to 5 million years ago.
Such is the nature of fieldwork: a constant gathering, synthesizing and imagining of information. How can I build a story about this place that incorporates all of the latest clues?
Today we’re looking for live snails so that we can measure how much carbon-14 they are incorporating into their calcite shells. Carbon-14 is a rare isotope of carbon that decays radioactively–organisms incorporate carbon-14 into their tissues and shells while they are alive, and as soon as they die, the carbon-14 starts decaying away. We can estimate how much carbon-14 there should have been in a shell, for instance, when the organism died, and we can measure how much is left: the difference tells us how long the shell has had to decay its carbon-14 away. Different organisms incorporate carbon differently, though, and it’s useful to get a modern sample (e.g. one that is alive, using carbon, when we find it) to compare to the older samples we find. The air is hot and still and the tufa coating on the rocks around us reflecs the sunlight, making the day feel hotter and brighter. We stalk snails in tiny inlets and pools, sifting through pebbles and combing through thick algae that will eventually decompose into tufa. We squat by the side of the lake for at least an hour but don’t see any signs of life, not even zooplankton. We can see flamingoes standing in the water at a distance, and other birds wheeling in the sky but what are they eating? Perhaps there are fish somewhere in this giant lake, but at its shoreline, all I can see is algae.
Later on, in the afternoon, we explore a stream cut that Jay had noticed, called Cerro Gorra. The stream had cut cleanly through former lake shores, leaving beautiful stratigraphic sections. We will spend time here in the next few days studying the layers and looking for shells.
A rapid technical response to the damaging earthquakes in Malawi produces both humanitarian and scientific benefits, and we hoped that both scientific and international assistance agencies would support our effort. Our seismic field effort serves two purposes: (1) to provide badly needed seismic equipment and technical training to the Malawi Geological Survey department (MGSD); and (2) to obtain unique data from very close to the earthquake sources to develop a better scientific understanding of faulting in the East African Rift. Funding has proven difficult, however, and our experience suggests that a technical component to earthquake response often falls through the cracks of the broader relief effort.
The Malawi earthquake sequence spawned a modest international response by several organizations with complementary and overlapping goals. The US Agency for International Development (USAID), through the Office of Foreign Disaster Relief (OFDA), and international organizations (e.g., Red Cross) provided direct humanitarian response: food, water, shelter, and other necessities for the displaced people of Karonga. Two scientists from the US Geological Survey (USGS), with support from USAID, provided a post-earthquake assessment based on field observations of damage and faulting, which constituted the official US government technical response.
Our technical response parallels those efforts, and is typical for the US academic community; individual scientists with existing contacts in and working knowledge of the effected region provide seismological field equipment, analysis, and training. Responding to the earthquakes in a timely manner required an almost instantaneous commitment on our part. Within two days after the largest event, IRIS had mobilized instruments and the funding necessary to ship them to the field. Lamont-Doherty Earth Observatory (LDEO) and the Earth Institute (EI), both at Columbia University, promised to “backstop” our effort – in other words, cover our travel and field expenses while we sought external funding for our effort. Both have strong and long-standing commitments to mitigating earthquakes, hazards, and human suffering worldwide, including in East Africa and Malawi. The project would have immediately stalled without this support.
With the LDEO and EI backstop in hand, we sought external funds from the National Science Foundation (NSF) and USAID, highlighting the unique scientific and outreach opportunities offered by a rapid response to these earthquakes (read our proposal here). USAID characterized the activity as too scientific to be in their purview and declined to fund us. NSF acknowledged a modest scientific benefit, but they described the effort as primarily a humanitarian and outreach response. While NSF agreed to provide some support, the amount available for such short-turnaround projects (via the RAPID program) is very small – enough only to return and recover our instruments.
Technical responses such as this one provide scientific and humanitarian benefits alike and strongly complement the larger response effort. The breadth of the impact should increase their fundability – more bang for the buck. But because of the splintered nature of the US response and funding mechanisms, this breadth can be a detriment to obtaining funding – too scientific to be humanitarian, but too humanitarian to be scientific. In our case, we overcame this quandary only with the strong financial support of our home institution. How many technical response efforts never get off the ground because of this funding uncertainty?
Lago Cardiel is much larger than I expected; we can barely see the opposite shore. This side is ringed by low hills and opens up like an apron, broad and gently sloping. As soon as we come through the hills, we notice well-defined former shorelines, which look like soap residue rings around a bathtub.
Shorelines make great natural roads, just as glacial outwash fields are apparently well-suited for airport runways because they are flat and drain well. JFK is built on a glacial outwash plain, Mike tells me.
We drive along until we spot an outcropping of basalt rock and carbonate tufa. Littered over this surface are the tiny white shells of dead snails which once lived near the shore. Their presence indicates that the lake shoreline must have been this high at some point. The shells must have been left when the lake receded.
The lake has grown and shrunk many times over the past 20,000 years. When it grows, it leaves behind a “bathtub ring” of residue around its edge: pebbles smoothed by wave action, carbonate tufas, the remnants of the things that lived at the shore. There are at least three distinct bathtub rings (each of which represents a time when the lake surface was higher than it is today) that we can see in a Google Maps printout we’ve been carrying around. But Scott Stine, a researcher who did his Ph.D thesis on Lago Cardiel, has identified other shorelines beyond the three we can see now.
To date these shorelines, Stine used the carbon-14 dating method on organic material linked to various shorelines to determine their age. His data suggested that the highest shorelines occurred about 10,000 years ago, at a time when the rest of South America was hot and dry. That would mean that this lake got really, really huge, mainly because of rainfall. Jay and Mike are unsure this happened, and think that instead the high shorelines may be older than everyone thinks. Maybe the lake was big about 20,000 years ago—the peak of the last ice age? Dating the shells and tufas again may resolve this question. So we’re looking for the highest shorelines, which is trickier than it might seem. We also have to find good material to date. That’s why Jay nearly jumped up and down with glee when we started finding shells. They’re great for doing carbon-14 analysis since we know the fossils once lived in the former lake. Jay and Mike call out questions as they search. Maybe this is the 55 meter shoreline? Are there other calcifying organisms that lived in the lake?
For most of our drive, I stare out the window and ask Mike questions: “Is that a glacial moraine?” and “How tall were the Andes originally?” and “Why are those sediments white?” He can respond to a stunning number of these questions. I love being around field geologists; the way they make sense out of visual clues that most of us overlook is both mysterious and fascinating.
We drive through a wide, deep canyon, with clearly exposed sedimentary sequences. “What are those dark layers?” I ask, and Mike explains that we’re driving through a Cretaceous sedimentary sequence. Some layers may be siltstone or shale-like deposits laid down when this area was submerged under a shallow sea.
Suddenly, Jay, who is driving ahead of us, stops his truck by the side of the canyon. “I just had to check this out,” he says, pulling his rock hammer out of the truck bed. “Look at this place!” Those dark layers are paleosols, or old layers of organic-rich soils preserved under other sediment, he tells us. And there’s siltstone, he points out. Barbara, his wife, tells us that they’ve found tons of fossils in similar siltstone beds on former trips.
A little further on we see thick, wind-deposited sand beds marked by a layer of volcanic tuff. The sand beds look like the beds forming at the surface today. I don’t know how strong the winds were when those beds were formed or how much sand and dust was in the air but the process that created them is the same that makes sand dunes today. There may have been dinosaurs stomping around and wildly different plants waving in the stiff breezes. But the winds picked up dust particles in the same way they do today. Biology tries out new body plans, reproductive systems and behaviors, and through it all, geology marches forward.
Jay and Barbara took off this morning in a rugged-looking truck while Mike and I followed in a Honda CR-V that looks more appropriate for Route 9W than Patagonia’s gravel roads. We’re hopeful that nothing terrible will go wrong. Wish us luck!
I was totally entranced by the geomorphology of this place: I must have taken 100 photos through the car windows. Everything is so flat! Even when there are basalt plateaus, they were flat on top. The view reminded me of Eastern Oregon, with its wide plateaus, basalt outcrops and gentle, sloping remains of braided rivers.
After a few hours of driving we pulled off the main road, towards Potrok Aike (“Aike” means “place” in Tehuelche, the native language of Patagonians). We didn’t know exactly where the lake was, but Jay had scoped the area out on Google Earth and plugged the lake’s coordinates into his GPS. On Google Earth, it looked as if a small road passed close to the lake. We found it.
I hadn’t realized how lucky we are in the U.S. to have reliable, highly-detailed topographic maps in most places. Apparently, in Potrok Aike and other places in Argentina, the maps are not as detailed or up to date.
So, why am I here, clunking down gravel roads and scrambling through dust? Yesterday I explained what Mike and Jay are doing. I am along for the ride, hoping to collect dust samples laid down during times in the past when the climate was different. My master’s project at Lamont, with my advisors Gisela Winckler and Mike Kaplan, is about dust deposition in Antarctica through different climatic stages.
The dust that drifted down to Antarctica at the peak of the last ice age appears to have come from southern South America, while the dust that arrives in Antarctica during warmer times, such as the last 10,000 years, seems to come from elsewhere. There was also a lot more dust deposited during the last ice age and earlier glacial periods.
I’m going to be analyzing geochemical isotopes found in dust collected in Patagonia and Australia to see if those samples match the dust found in ice cores from Antarctica. So that’s why I’m here, to find out if ancient dust collected in Patagonia is similar to dust found thousands of miles away, from thousands of years ago. This will help us understand how the climate of the Southern Hemisphere worked in the past.
I’ve been to Stewart Island, off the southern tip of New Zealand, but I’m pretty sure this is the furthest south I’ve been. Cool!
We’re here in Rio Gallegos. We’ve just rendezvoused with Dr. Jay Quade, a geologist from the University of Arizona, and his wife Barbara. We’ve got two cars, a bunch of boxes of food, and plenty of gear; hopefully we’re ready for eight days in the field. Tomorrow, we’re going to drive across Patagonia toward some lakes at the eastern foot of the Andes.
Mike is a glacial geologist based at Lamont. Much of his research has focused on figuring out when the Andean ice sheets, which today are nestled in the highlands and only poke toes out toward the Patagonian plains, grew and shrank. When they grew, they extended incredible distances out of the Andes. When they shrank, they left behind moraines, tills, and tons of ground-up rock. Mike wants to know if these glaciers grew at the same time as the northern hemisphere glaciers. When New York was covered in ice, was Patagonia? Are the Southern and Northern hemispheres glaciating in or out of phase?
Jay is an expert on paleolakes. He’s also interested in reconstructing the history of the South America’s climate. He can tell when a lake was high, in the past, and if he can date that high, he can infer something about the climate system that existed at that time.
We’re headed to Lago Potrok Aike and Lago Cardiel, which are both special and strange. They’re closed-basin lakes, with no outlets, fed by rivers and streams unconnected to the glaciers that feed most of the lakes around them. Therefore, the water level is controlled almost entirely by rainfall (and seasonal snowmelt) in the surrounding watershed, with some influence from surface evaporation.
The lakes are therefore sensitive recorders of the climate system. You can’t find a much more straightforward natural system than these closed-basin lakes!
I’m tagging along with these guys to get samples for my master’s research project. I’m hoping to find dust that was deposited roughly at the time that the last ice age hit its peak, about 20,000 years ago. I’ll explain more tomorrow, but for now, I hope I’ve piqued your curiosity. Dust: way more exciting than you ever would have thought!
We arrived in Argentina after a night in the air—maybe the first time I’ve ever gotten a (nearly) decent night’s sleep on a plane. We took a taxi across the city. It’s hot and flat, and our taxi driver explains that they’ve had torrential rains for several weeks; all the lowlands alongside the highway are filled with shimmery, temporary swamps. “We usually have picnics there,” he says, pointing to a shallow pond thick with grass poking up through the surface. “But this summer has been strange and wet.”
I am on my way to Patagonia with Michael Kaplan, a researcher at Lamont who is part of my master’s committee. We’re here to study how climate in South America was in the past. One reason I’m interested in paleoclimate research is because I’d like to understand our modern climate system better, and what the future might look like. “Climate,” by definition, operates on a time scale longer than seasons or even years, so this wet summer is just another point in some larger dataset, but it’s interesting nonetheless.
We get to the small intra-national airport and drop off our bags with time enough to wander down the riverside walkway outside the airport. It’s sweltering and steamy, but Mike tells me that when we get to Rio Gallegos, just north of Tierra del Fuego, I’ll be glad I brought warm clothes.
Tomorrow I’ll explain our exact plan. For now, I’m going to make sure that I get a window seat so I can look at the topography beneath us as we fly nearly directly south. To Patagonia we go!
Going to Antarctica involves a whole lot of paperwork. Before I left, I filled out an extensive medical history, was tested for every disease imaginable, gave my pants size, shoe size, hat size, until I had only one form remaining. That was the waiver acknowledging that working in Antarctica is inherently dangerous and that by going I was agreeing to certain risks. I signed it without a second thought.
Over the last few days, I’ve thought of little else. Four days ago, Greg Balco set out to search for glacial erratics on James Ross Island, a few miles away. He was accompanied by Doug Fox, a science writer for National Geographic. Their helicopter pilot, Barry James, was flying them back to the ship when the weather worsened and he was forced to make an emergency landing.
Their first night on the ice, the rest of us imagined them in their tents, eating from their survival kits and munching on chocolate bars undoubtedly stuffed in their packs. But the weather did not improve the next day, and science operations were again suspended. Their third day out, the weather worsened with whiteout conditions, and it was clear that they would spend another night on the ice. Through frequent communications via iridium phone, they assured us that they were safe in their tents. We began to speculate on which movie star would play whom in the blockbuster-version of their story. We tried not to think about what would happen if the weather didn’t clear soon.
On the fourth day, Chris Dean, our remaining helicopter pilot, took off in a second helicopter for James Ross Island, but turned back due to poor visibility. He tried again a few hours later and radioed the ship to tell us they were arriving. We climbed to the bridge to watch them land. Our ship blasted its foghorn in welcome. Everyone was fine and clearly less worried than we were. They returned just in time for supper.
The ideal spot for a seismic station is dry, quiet and safe from vandals and thieves. Seismometers record slight ground motions, allowing them to hear distant (and not so distant) earthquakes. But cars or even kids playing near a seismic station can produce ground vibrations that overwhelm the subtle sounds of earthquakes. Seismic stations include plenty of expensive, high-tech instruments that are worthless to the average person. But they also contain mundane items that can be useful, such as 12-volt batteries and insulated wiring, making theft a problem. And water is the enemy.
Malawi presented novel challenges for siting our stations. Our first priority was to find dry, secure locations to prevent damage and loss. As we drove into the Karonga region for the first time, our hearts sank; the epicentral region is low-lying and wet, small villages surrounded by rice paddies. Our arrival during the rainy season did not help.
But with a little hunting, we were able to find high and dry spots for most of our stations. We bumped along narrow village tracks in our rented 4×4, occasionally getting stuck on particularly muddy sections. Most of the dirt roads did not appear on our outdated maps, so we stopped regularly to ask for directions. When our Malawi colleagues explained that we were there to learn about the chindindindis (Tumbuka for earthquakes), they were eager to help!
In many parts of the world, safety and quiet can be achieved simultaneously simply by deploying stations in the middle of nowhere. This is not an option in densely populated Malawi, where one farming village abuts another. Main thoroughfares and small dirt roads alike were crowded with kids walking to school, villagers biking to town, and farmers grazing their goats and sheep. Instead, we sought out village police, teachers, and other officials for help finding safe spots. In some cases we hired guards to look after them.
We spent hours driving, inspecting sites and waiting to meet with officials. We normally skipped lunch, fueling ourselves instead on passion fruit-flavored Fantas and “puffs” (kids junk food akin to cheese doodles). But these efforts paid off – we found good sites for our equipment and started listening.
As a child, I believed that I could hear the ocean in a seashell. Now when I think about the sounds of the sea, I imagine the roar of waves crashing on the beach. But from the vantage point of a ship with noisy engines, the water seems silent.
In 1490, Leonardo da Vinci observed, “If you cause your ship to stop, and place the head of a long tube in the water and place the outer extremity to your ear, you will hear ships at a great distance from you.” The observation that sound travels well in water became the basis for the sophisticated sonar systems developed in World War I and II for submarines. The science that formed the basis for those technologies can also be used to explore the ocean.
The ship uses acoustic energy to map the sea floor and sub-seafloor. I measure ocean currents using higher-frequency acoustic pulses that bounce off particles in the water. But I never hear those data as sound; I simply process a digital signal into maps of velocity.
Dr. Erin Pettit, a glaciologist at the University of Alaska, wants to use sound to measure the melt rates of glaciers. The interface between ice, ocean, and bedrock is a site of glacial melting but is difficult to access. It may be possible to use passive acoustics – only listening, not sending out pulses of sound – to quantify the processes in these locations. To test that idea, Erin uses hydrophones to record sounds around glaciers and sea ice.
Erin is currently working on the nearby Flask Glacier. She left the hydrophones with me and Yuribia Muñoz, a student from the University of Houston, so that we could start recording sounds without her. Today was our first opportunity: overcast skies, intermittent snow and a relatively pleasant -2.5˚C (27.5˚F). On foot, we crossed over sea ice, more than a meter thick, floating on top of 500 meters of water. After a core was drilled through the ice to study the algae within it, we lowered two hydrophones into the hole, up to 15 meters down.
What I heard from the hydrophones sounded like a quiet crackling, with some interference from the ship and people walking on the ice above. These data will allow us to relate the sounds of ice to the physical processes that control it and will hopefully show that passive acoustics can be used to quantify rates of melting.
The view from the Palmer is so blindingly white today that the eye cannot tell where the ice ends and the clouds begin. In this unusually icy Antarctic summer, it seems strange to contemplate melting ice. But glaciers, here and in Greenland, are melting faster than they are growing. We know that ice sheets have been around for thousands of years, but certain areas are currently melting and breaking off into the sea at rates that far exceed their growth. The breakup of 3,320 square kilometers (1,282 square miles) Larsen B ice shelf in 2002 was only the most dramatic example.
It is clear that we are losing ice faster than we have since reliable observations began. But those observations have only been made since the advent of satellites in the 1970s. How can we resolve the difference between the rates of ice sheet destruction and their long history on earth?
There are three hypotheses that I’m familiar with, but you are welcome to leave additional possibilities in the comments. The first is that global climate change is responsible. This makes intuitive sense, as we associate warmer temperatures with melting. But air temperatures, at least, are so far below freezing in most of Antarctica that raising them a few degrees will not lead to melting. On the other hand, glacial dynamics are not well understood, and temperatures in the water underneath ice sheets are hard to measure and could have a large effect.
Another possibility is that ice sheets are still responding to the last ice age. They could still be reaching equilibrium with our modern, pre-industrial climate. There is evidence that the increase in sea level, which began as the ice age ended, has slowed considerably in the last seven thousand years but is not quite over.
A third alternative is that short-term ice sheet variability is simply much larger than long-term variability. There is limited evidence from western Antarctica that glaciers can flow quickly for years and then stop abruptly.
The difficulty now is that we simply don’t have enough data to evaluate these hypotheses. That’s why the Nathaniel B. Palmer is trying to push through the seemingly impenetrable ice to reach the Larsen area. If we can get there and examine the local glacial history of the area, we may be able to place the Larsen breakup in historical context and understand what it means for the rest of the world and for the future.
Thanks to Greg Balco from the Berkeley Geochronology Center for his explanation of glacial geology.
Working in Antarctica is always a challenge but this trip has had more than the usual setbacks. After working feverishly in Punta Arenas to prepare our ship, we had to wait two days for some essential cargo to arrive. Not long after pushing off, we encountered rough weather in the Drake Passage, a region notorious for unkind seas. The ship pitched and heaved, but the storm was brief, and we sailed out of the weather after one day.
Our planned route to the Larsen B embayment took us around the tip of the peninsula to the eastern side and south through Prince Gustav Channel, where we were stopped by an impressive field of sea ice. The sea ice around Antarctica typically retreats in austral summer—December through February—and grows again in early April. We had hoped the sea ice would retreat enough to allow us easy passage to Larsen B. This year, though, the ice in the Weddell Sea had not retreated very much, forcing us to come up with a back-up plan.
We had planned to fly over several glaciers in a helicopter, to install instruments that would automatically record ice movement and weather. Some of the sites happened to be accessible from the western side of the peninsula, where there is no sea, so we decided to sail there and wait for the ice to melt on the eastern side. We arrived on Jan. 14, but bad weather has prevented us from taking the helicopter up.
While waiting for better conditions, we are taking measurements in several fjords along the western coast. We are now in the Gerlache Strait, a popular site for cruise ships because of its spectacular scenery and whale watching. So far we’ve seen humpback and minke whales feeding in the calm iceberg-studded waters.
The setbacks have given us an unexpected opportunity to learn more about this fascinating part of the Antarctic Peninsula ecosystem. We will soon head back to the Larsen side to test the sea ice again, with our instruments ready to go.
The nice folks up on the bridge always give us a call when they see wildlife. Then we all grab our cameras and rush out to our favorite spots to try and photograph whatever creatures have come to visit.
I’m no biologist, but seeing so many beautiful animals has made me curious. So I’ve been doing a little reading and I’d like to share with you what I’ve learned about some of our favorite visitors, the Adelie penguins. This photo of the Adelies was taken a few days ago by Caroline Lavoie.
Adelies are only 30 inches tall and weigh about 11 pounds. But millions of years ago, there were penguins that stood 5 feet tall and weighed 200 pounds! They’re not alive today, and I’m having trouble imagining them.
While many of us associate penguins with Antarctica, they’re actually spread all over the Southern Hemisphere, with a few living right on the equator. There are seventeen species of penguins, but only Adelies and emperor penguins live exclusively in Antarctica.
While I’ve been staying on the ship, Erin Pettit has been flying off by helicopter to study glaciers. She has a really cool job, and I wish she would take me with her on some of her adventures. But it turns out that she wants to take you!
Erin runs a program called Girls on Ice. Every year since 1999, she takes 9 teenage girls to Mt. Baker in Washington State for 11 days. The program is FREE and applications are available now at http://girlsonice.org/apply. Those of you at DLMS are a little too young for the program, but I want you to start thinking about it now so that you’ll be all set to apply in a few years. And tell your friends!
This isn’t just about getting to visit somewhere new and beautiful with an awesome scientist. You’ll learn how to study glaciers, how to climb glaciers, how to stay safe on glaciers, and you’ll even work with an artist to learn how to draw glaciers. And don’t worry: you don’t need any experience, you don’t need perfect grades, and you don’t even need to be sure that you want to be a scientist. You just need to be interested in learning more about the earth and in challenging yourself.