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Large-scale groundwater pumping is opening doors for dangerously high levels of arsenic to enter some of Southeast Asia’s aquifers, with water now seeping in through riverbeds with arsenic concentrations more than 100 times the limits of safety, according to a new study from scientists at Columbia University’s Lamont-Doherty Earth Observatory, MIT, and Hanoi University of Science.

Human actions are changing the oceans’ chemistry. To predict how marine ecosystems are going to respond to these changes, we need to understand how marine biology and ocean chemistry interact today. This week, biologist and geochemists from around the world gathered at Lamont to find new ways to combine their expertise to analyze GEOTRACES data on trace elements and nutrients.

In the big data era, the modern computer is showing signs of age. The sheer number of observations now streaming from land, sea, air and space has outpaced the ability of most computers to process it. As the United States races to develop an “exascale” machine up to the task, a group of engineers and scientists at Columbia have teamed up to pursue solutions of their own.

A huge earthquake may be building beneath Bangladesh, the most densely populated nation on earth. Scientists say they have new evidence of increasing strain there, where two tectonic plates underlie the world’s largest river delta. They estimate that at least 140 million people in the region could be affected if the boundary ruptures; the destruction could come not only from the direct results of shaking, but changes in the courses of great rivers, and in the level of land already perilously close to sea level.

A 4,000-foot-high mountainside collapsed in Glacier Bay National Park in a massive landslide that spread debris for miles across the glacier below. It was a powerful reminder of the instability of the mountains in this part of Alaska and the risks that that instability creates. Scientists at Lamont discovered the landslide from its seismic signature and are studying it and another recent Alaska landslide and tsunami to improve understanding of landslide risks to this region and globally.

Antarctic sea ice is constantly on the move as powerful winds blow it away from the coast and out toward the open ocean. A new study shows how that ice migration may be more important for the global ocean circulation than anyone realized.

Engaging educators through professional development workshops, public events, and lectures is an important part of the Observatory’s education and outreach mission. Earlier this month, two dozen middle- and high-school educators joined a group of Lamont scientists at a workshop to learn about paleoclimate techniques and how computer models can expand understanding of the causes of hydroclimate variability and changes over the last several millennia.

The tropics are already hot, and they’re getting hotter as global temperatures rise. A new study offers a glimpse into just how severely a couple more degrees could disrupt the region’s ecological map. The authors, from Lamont-Doherty Earth Observatory and the University of California, Berkeley, looked at potential effects of a 2°C rise in the average global temperature this century and asked: what would happen if all species tried to migrate to keep their average environmental temperature unchanged?

Who were our earliest ancestors? How and when did they evolve into modern humans? And how do we define “human,” anyway? Was it when some long-ago ancestor stood and walked; grew a brain of a certain size; or figured out how to make stone tools, control fire, plant crops or brew beer? The possible answers to such questions are themselves evolving, as anthropologists and archaeologists including Lamont's Chris Lepre continually discover new fossils and artifacts that upset old theories and push the known dates of evolutionary milestones back ever further into the past.

Buried deep in seabed sediments off east Africa, scientists have uncovered a 24-million-year record of vegetation trends in the region where humans evolved. The authors say the record lends weight to the idea that we developed key traits—flexible diets, large brains, complex social structures and the ability to walk and run on two legs—while adapting to the spread of open grasslands. The study appears today in a special human-evolution issue of the journal Proceedings of the National Academy of Sciences.

The plate tectonics revolution was a data revolution. The young scientists who led the charge 50 years ago showed how asking the right questions and having access to a wide range of data could open doors to an entirely new understanding of the planet. This week, those scientists and the generations they inspired are meeting at Lamont to look back on their discoveries and to discuss the scientific developments over the decades since that continue to build our understanding of the behavior of Earth’s tectonic plates.

On a ledge just inside the lip of Chile’s Quizapu volcanic crater, Philipp Ruprecht was furiously digging a trench. Here at an elevation of 10,000 feet, a 1,000-foot plunge loomed just yards away, and wind was whipping dust off his shovel. But the volcanologist was excited. Ruprecht had just found this spot, topped with undisturbed wedding-cake layers of fine, black material that the crater had vomited from the deep earth some 84 years ago. Samples from the currently inactive site might shed light on its exceedingly violent behavior.

One of Earth’s newest islands exploded into view from the bottom of the southwest Pacific Ocean in January 2015. Lamont scientist Vicki Ferrini, who uses geophysical mapping techniques to study the seafloor, was sailing through the area on an unrelated research cruise and created a detailed map of the new island's topography.

Maureen Raymo, a marine geologist and paleoceanographer whose name is connected with key theories about how ice ages wax and wane and how sea levels change, has been elected to the National Academy of Sciences, one of the highest honors awarded to engineers and scientists in the United States. She is the 11th current scientist from Columbia University’s Lamont-Doherty Earth Observatory invited to join the Academy for their excellence in original scientific work.

A new statistical method inspired by economics is helping scientists identify old volcanic eruptions through temperature changes in a consistent, automated way. In addition to helping separate volcanic impacts on climate from random climate variability, the new method has a wide range of policy applications.

Christopher Scholz is being awarded the Harry Fielding Reid Medal for his pioneering work in rock mechanics and his skill at communicating earthquake science. The Seismological Society of America cites Scholz’s wide range of contributions over a nearly 50-year career.

Researchers have predicted that as the planet is warmed by human-produced CO2, plants may add to the emissions and amplify the warming. Now, the most comprehensive global study of its kind yet suggests that this effect has limits, and that increases in plant respiration may not be as big as previously estimated. It shows that rates of increase slow in an easily predictable way as temperatures mount, in every region of earth, from tropics to tundra.

Jay Ardai was the guy you wanted in your sea ice camp after the ship left, or in the Alaska wild when your plane had mechanical trouble. He earned his reputation in remote locations like these as a super-technician who could fix anything using whatever he could find.

One foggy spring morning just after a hard rain, Park Williams was tromping through the woods deep in Arkansas’ Ozark Mountains. Toiling down a steep slope, he supposedly was keeping a simultaneous eye out for rattlesnakes, copperheads, poison ivy and big old trees. Williams seemed mostly focused on the trees, though; attention to the other stuff was just slowing him down. Williams studies how forests react to changes in climate, and the Ozarks’ deeply dissected hills and hollers are a kind of ground zero for this.

Mercury’s dark surface is revealing intriguing new clues about the formation of the solar system, including evidence described in a new study that the planet closest to the Sun may have formed in part from carbon, a key component of life.

Greenland's snowy surface has been getting darker over the past two decades, absorbing more heat from the sun and increasing snow melt, a new study of satellite data shows. That trend is likely to continue, with the surface's reflectivity, or albedo, decreasing by as much as 10 percent by the end of the century, the study says.

When you examine the behavior of the global oceans closely – really closely, at scales smaller than 100 kilometers – eddies and jets and fronts start to appear. For Ryan Abernathey, who was just awarded a 2016 Sloan Research Fellowship, this is where ocean physics gets interesting.

Deep beneath Alaska’s Aleutian Islands, down where the pressure and temperatures have become so high that rock starts to flow, new continental crust is being born. Scientists have long believed that continental crust forms in volcanic arcs – they know the magma brought up in the arcs’ volcanoes is geochemically very similar to continental crust. The lingering question has been how exactly that happens. While the magma that reaches the surface is similar to continental crust, the lower crust beneath volcanic arcs is quite different from the lower half of continental crust.

Last Thursday, thousands of people from southern New Jersey to Long Island and coastal Connecticut felt the earth tremble. Between 1:20 pm and 2:40 pm, dishes, desks and buildings shook for up to 20 seconds—in some locations, several times. With everyone thinking earthquake, Twitter and Facebook lit up; news reporters scrambled; calls poured into police, the U.S. Geological Survey, and Columbia University’s Lamont-Doherty Earth Observatory, which maintains the region’s network of 50-some seismographic stations.

On every continent and ocean, Lamont-Doherty Earth Observatory field researchers are studying the dynamics of climate, geology, natural hazards and ecology, and their practical applications to modern problems. Below are some of their expeditions in rough chronological order. Work in and around New York City and the U.S. Northeast is listed separately toward bottom. Use the interactive world map above to explore these projects.

In an effort led by current and former Lamont Tree Ring Lab scientists, the N-TREND consortium (Northern Tree-Ring Network Development) was created to develop a global database of tree-ring research that improves on efforts for developing large-scale temperature reconstructions across the Northern Hemisphere.

In the water above natural oil seeps in the Gulf of Mexico, where oil and gas bubbles rise almost a mile to break at the surface, scientists have discovered something unusual: phytoplankton, tiny microbes at the base of the marine food chain, are thriving. The oil itself does not appear to help the phytoplankton, but the low concentration of oil found above natural seeps isn’t killing them, and turbulence from the rising oil and gas bubbles is bringing up deep-water nutrients that phytoplankton need to grow, according to a new study appearing in the latest issue of Nature Geoscience.

As the second most recent ice age was ending and its glaciers began to retreat, the Earth experienced a large, abrupt climate change that shifted the thermal equator southward by about 4 degrees, according to a new study that for the first time tracks that shift in millennial detail, showing how the Northern Hemisphere cooled and the Southern Hemisphere warmed over the span of a few hundred years. The change would have affected the monsoons, today relied on to feed more than half the world’s population, and could have helped tip the climate system over the threshold for deglaciation, said lead author Allison Jacobel.

Over the last six years, seismologists Göran Ekström and Colin Stark have been perfecting a technique for picking out the seismic signature of large landslides from the stream of seismic data from earthquakes and other activity around the world. The details they are able to extract could one day help governments sound tsunami warnings, help rescuers find landslide-struck villages faster, and warn of risks such as landslide-dammed rivers that could soon burst through.

Understanding how lava flows is critical when homes and roads are in a lava flow’s path. A community may have a day to evacuate, or its residents may have a week or more, with enough time to move what they can to safer ground.

A new study questions the popular notion that 10^th-century Norse people were able to colonize Greenland because of a period of unusually warm weather. Based upon signs left by old glaciers, researchers say the climate was already cold when the Norse arrived—and that climate thus probably played little role in their mysterious demise some 400 years later. On a larger scale, the study adds to building evidence that the so-called Medieval Warm Period, when Europe enjoyed exceptionally clement weather, did not necessarily extend to other parts of the world.

When the most recent eruption of Hawaii’s Kilauea volcano started last June, Melvin Sugimoto at first did not think much of it. Hawaii, where he has lived all his life, is made entirely of hardened lava, and Kilauea, perhaps the world’s most active volcano, has been adding more off and on for the last 300,000 years. “Lava is everywhere, but I never thought in a million years it would come through here,” said Sugimoto, who lives in the small town of Pahoa.

Earth’s magnetic field has been getting weaker, leading some scientists to think that it might be about to flip, but the field may simply be coming down from an abnormally high intensity rather than approaching a reversal, scientists write in a new paper published online this week in the Proceedings of the National Academy of Sciences.

The Indonesian peat fires that have been choking cities across Southeast Asia with a yellow haze are creating more than a local menace—the burning peat releases immense stores of CO2, contributing to global warming, writes Jonathan Nichols.

Gradual melting of winter snow helps feed water to farms, cities and ecosystems across much of the world, but this resource may soon be critically imperiled. In a new study, scientists have identified snow-dependent drainage basins across the northern hemisphere currently serving 2 billion people that run the risk of declining supplies in the coming century. The basins take in large parts of the American West, southern Europe, the Mideast and central Asia. They range from productive U.S. farm land to war-torn regions already in the grip of long-term water shortages.

The long history of severe droughts across Europe and the Mediterranean has largely been told through historical documents and ancient journals, each chronicling the impact in a geographically restricted area. Now, for the first time, an atlas based on scientific evidence provides the big picture, using tree rings to map the reach and severity of dry and wet periods across Europe and parts of North Africa and the Middle East year-by-year over the past 2,000 years.

The global overturning circulation of the ocean plays a fundamental role in our climate by redistributing some of the excess heat accumulated around the Equator. The coldest deep waters of the global circulation are created in localized regions near the poles. How these deep waters return to shallower depths through vertical mixing is still not, as yet, fully understood.

The Research Vessel Marcus G. Langseth, operated by Columbia’s Lamont-Doherty Earth Observatory, sails the world exploring oceans and probing the sea floor and the layers deep beneath it. A new video produced by Columbia University takes a tour of the Langseth and talks to the scientists who work on its decks collecting data.

Tiny microbes called phytoplankton are churning away in the oceans, taking in carbon dioxide and producing the oxygen we breathe. Scientists recognize their value, but many questions remain about what will happen to their productivity as the oceans warm, carbon dioxide levels rise, and the nutrients they rely on become scarce. A new study explores those questions using a mix of techniques from genomics and oceanography and a newly created database of millions of phytoplankton RNA strands contributed by scientists from labs around the world.

A new study finds that the Horn of Africa has become progressively drier over the past century and that it is drying at a rate that is both unusual in the context of the past 2,000 years and in step with human-influenced warming. The study also projects that the drying will continue as the region gets warmer. If the researchers are right, the trend could exacerbate tensions in one of the most unstable regions in the world.

As Superstorm Sandy headed for New York City, Adam Sobel’s phone started ringing with calls from reporters, and it kept ringing as the subway tunnels filled with water, the storm passed, and the city started to clean up. The reporters wanted to understand the science behind the storm and what it meant for the future. Their questions and Sobel’s conversations with colleagues across Columbia University working on issues related to extreme weather inspired him to write “Storm Surge,” a 2014 book about Sandy that just won the American Meteorological Society’s Louis J. Battan Author’s Award.

Ancient pollen grains that were floating in the air when mammoths roamed Southern California are providing new insights into historic droughts in the region, including how a series of mega-droughts between about 27,500 and 25,500 years ago changed the ecological landscape. A new scientific paper tracks these changes and suggests that warm ocean conditions similar to what we see off Southern California today fueled that 2,000-year stretch of droughts.

What makes someone a good mentor? Is it the way she is always available, even when 3,000 miles away? Or the way he gets to know his students as individuals who have lives outside the lab? We got some insight last night from two award-winning mentors and the students whose lives they have changed.

“In the last 10 years, we were afraid that the Southern Ocean was going to quit giving us a break from climate change,” said coauthor Taro Takahashi of Columbia University’s Lamont-Doherty Earth Observatory. “This study shows that it’s recovered its ability to take up carbon dioxide, and that’s good news.” Takahashi has been working for decades to understand the cycling of CO2 between air and oceans, and is regarded as one of the world’s leading authorities on the subject.

The Amazon Rainforest sprawls across more than 2 million square miles of South America, taking in carbon dioxide and releasing oxygen as “the lungs of the planet.” When they’re healthy, the world’s tropical forests and vegetation absorb up to 30 percent of the CO2 produced by human activities, but during droughts, that capacity falls off. To understand what that will mean as global warming produces more intense and frequent droughts, we need to understand the water and carbon cycles of the Amazon and how those cycles interact.

People have been finding loose diamonds across the United States and Canada since the early 1800s, but for the most part, no one knows where they came from. It was not until the 1990s that geologists tracked down the first commercial deposits, on the remote tundra of Canada’s Northwest Territories. Yaakov Weiss, a geochemist at Columbia University’s Lamont-Doherty Earth Observatory, is investigating the origins of these rich diamond mines. He also hopes to explore the mysteries of the much rarer loose stones found in places like the U.S. Rockies and rural Arkansas. Will prospectors ever make a big strike closer to civilization? Here, a brief pictorial look at the history and science of North American diamonds. It is based on the book Barren Lands: An Epic Search for Diamonds in the North American Arctic.

A new study says that global warming has measurably worsened the ongoing California drought. While scientists largely agree that natural weather variations have caused a lack of rain, an emerging consensus says that rising temperatures may be making things worse by driving moisture from plants and soil into the air. The new study is the first to estimate how much worse: as much as a quarter. The findings suggest that within a few decades, continually increasing temperatures and resulting moisture losses will push California into even more persistent aridity. The study appears this week in the journal Geophysical Research Letters.

In the D’Entrecasteaux Islands off Papua New Guinea, the rocks are giving rise to new ideas about the ways in which mountain chains form. A new scientific model inspired by data from the islands shows how the seemingly opposite processes of tectonic compression and extension can take place in the same region.  It also shows how sections of earth’s crust that have been pushed deep under the surface can reverse course and rise in what in the geological time scale would be an instant. The model has implications for the understanding of how many mountain belts form.