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  • Lamont-Doherty Earth Observatory | Lamont-Doherty Earth Observatory
    the news Warming World Means More Drought in Horn of Africa The Ecologist October 18 What s Behind the Disappearance of Antarctic Snow Christian Science Monitor October 16 Air Guard s IcePod Aircraft Departs for Deep Freeze DVIDS October 16 Climate Cycles Didn t Shape Ocean s Abyssal Hills Science October 15 The Mystery of Antarctica s Strange Disappearing Snow Live Science October 15 More In the spotlight APPLY FOR A POSTDOCTORAL FELLOWSHIP DEADLINE NOV 16 October 2015 Newsletter Horn of Africa Drought Antarctic Winds and More New Columbia Initiative on Extreme Weather and Climate September 2015 Newsletter Tree Ring Lab Turns 40 California Drought and More April 2015 Newsletter Our Strategic Plan Stemming Climate Change and More Explore Our Impact Lamont 2014 Annual Report Explore Our Blog and Learn More About Lamont January 2015 Newsletter 2015 Vetlesen Prize Recipient Fogo Volcano and More November 2014 Newsletter Ocean Acidification Mysterious Mountains and More October 2014 Newsletter A Top Scientific Honor STEM Education and More Previous Pause Next blogs videos Blog Mapping Lava Flows in Iceland Video At Sea with the R V Marcus G Langseth Blog SUGAR SUwanee Suture and GA Rift basin experiment Blog TRACES of Change in the

    Original URL path: http://www.ldeo.columbia.edu/ (2015-10-19)
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  • Study Sees Powerful Winds Carving Away Antarctic Snow | Lamont-Doherty Earth Observatory
    more than 50 feet of snow equal to 200 years accumulation The scientists identified thousands of similar sites using satellite imagery This persistent loss has created pockets where the surface is eroding about as fast as ice flows in That means the surface retains its shape but in fact is exporting mass In the past warmer climates have brought more snowfall to Antarctica and this could happen again now so knowing where all that snow ends up could become increasingly important The research was led by Indrani Das a geophysicist at Columbia University s Lamont Doherty Earth Observatory We need to get the physics right said Das The ice surface and the scouring process are tied together with climate Some 7 percent of Antarctica is covered by wind scour zones green where snow is persistently swept away by high powered winds Das et al As snow falls in Antarctica it builds up layers on the ice sheet Researchers can see these layers in radio echo images and ice core samples In East Antarctica where the researchers did their work Das noticed irregularities on the radar images landscapes where snow had accumulated as expected and then sections where the layers disappeared for a few kilometers then resumed These were wind scour zones sometimes called glaze for their buffed ice surfaces Das developed an empirical model described in a 2013 Nature Geoscience paper that could locate the scour zones She then used satellite data from earlier research led by glaciologist Ted Scambos of the University of Colorado s National Snow and Ice Data Center to validate it In the new study Das and Scambos with help from models produced by the University of Utrecht s Michiel van den Broeke took the next step to quantify the snow loss and describe the physics involved We identified new processes that we didn t fully appreciate before said Scambos Scour zones are created by East Antarctica s persistent katabatic winds Because the air directly above the ice is colder and denser than warmer layers above it gets trapped and accelerates quickly down steep slopes reaching speeds of up to 25 meters per second 55 miles per hour With temperatures between minus 20 and minus 80 degrees Celsius minus 4 and minus 112 Fahrenheit the snow never melts but it does sublimate the winds break up the already brittle snow causing it to blow away and in many cases evaporate directly from solid to gas To determine what was happening at the scour zones Das needed to know the age of the surrounding snow layers and their density She used existing dated ice cores from Eastern Antarctica s Recovery Ice Stream region to identify volcanic ash horizons from the 1815 Mount Tambora eruption in radio echo profiles of the snow layers Das could see that in some regions snow layers below the Tambora layer were exposed at the edge of scour zones by the ablation process Furthermore radar images revealed that only a small amount of

    Original URL path: http://www.ldeo.columbia.edu/news-events/study-sees-powerful-winds-carving-away-antarctic-snow (2015-10-19)
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  • Horn of Africa Drying in Sync with Climate | Lamont-Doherty Earth Observatory
    for the Horn of Africa but our findings show that the exact opposite is occurring The region is drying and will continue to do so with rising carbon emissions said study coauthor Peter deMenocal who heads the Center for Climate and Life at Columbia University s Lamont Doherty Earth Observatory The study appearing in this week s Science Advances used a sediment core that deMenocal and his colleagues extracted from the pirate ridden Gulf of Aden They used the core to infer past changes in temperature and aridity By pairing the paleoclimate record from the core with 20 th century observations the researchers determined that drying will probably continue across Somalia Djibouti and Ethiopia That contradicts more optimistic models that have suggested future warming might bring rainier weather patterns that could benefit the region What we see in the paleoclimate record from the last 2 000 years is evidence that the Horn of Africa is drier when there are warm conditions on Earth and wetter when it is colder said lead author Jessica Tierney an associate professor at the University of Arizona and former postdoctoral associate at Lamont Doherty Global scale models used to predict future changes under global warming suggest that the region should become wetter primarily during the short rains season from September to November But the new study suggests that those gains may be offset by declining rainfall during the long rains season from March to May on which the region s rain fed agriculture relies The outcome has serious implications for a region that has been racked with political instability and violence as it has dried The Horn of Africa has suffered deadly droughts every few years in recent decades and with them humanitarian crises as famine and violence spread It has also become one of the most unstable regions in the world In Somalia as the political situation deteriorated amid droughts of the 1980s and 90s hundreds of thousands of refugees fled the country and pirates began raiding ships off the coast Study coauthor Peter deMenocal left took this deep sea core in the pirate infested Gulf of Aden Lead author Jessica Tierney right performed an analysis linking greater heat in the past to drier conditions Courtesy Lamont Doherty Earth Observatory To extract the sediment core used in the study scientists had to evade those pirates in the Gulf of Aden Lamont Doherty s R V Maurice Ewing had been attacked with rocket propelled grenades during a previous trip On this run the captain of the Dutch research ship Pelagia turned off the ship s interior and navigation lights to slip through these waters Around them other vessels were reporting pirate attacks That sediment core which dates back about 40 000 years has already provided new insights into Africa s climate In a 2013 study analyzing parts of the core Tierney and deMenocal showed that the Sahara which once bloomed with regular rainfall suddenly dried out over the span of a century or two during

    Original URL path: http://www.ldeo.columbia.edu/news-events/horn-africa-drying-sync-climate (2015-10-19)
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  • Signs of Ancient Megatsunami Could Portend Modern Hazard | Lamont-Doherty Earth Observatory
    2004 and eastern Japan in 2011 reached only about 100 feet Like most other well documented tsunamis these were generated by movements of undersea earthquake faults not volcanic collapses The wave generated by Fogo s collapse apparently swept boulders like this one up from the shoreline into Santiago island s highlands Here a researcher chisels out a sample to establish the date of the tsunami Ricardo Ramalho Santiago Island lies 55 kilometers 34 miles from Fogo Several years ago Ramalho and colleagues were working on Santiago when they spotted unusual boulders lying as far as 2 000 feet inland and nearly 650 feet above sea level Some are as big as delivery vans and they are utterly unlike the young volcanic terrain on which they lie Rather they match marine type rocks that ring the island s shoreline limestones conglomerates and submarine basalts Some weigh up to 770 tons The only realistic explanation the scientists could come up with A gigantic wave must have ripped them from the shoreline and lofted them up They derived the size of the wave by calculating the energy it would have taken to accomplish this feat To date the event in the lab Ramalho and Lamont Doherty geochemist Gisela Winckler measured isotopes of the element helium embedded near the boulders surfaces Such isotopes change depending on how long a rock has been lying in the open exposed to cosmic rays The analyses centered around 73 000 years well within the earlier French estimate of a smaller event The analysis provides the link between the collapse and impact which you can make only if you have both dates said Winckler The tsunami also scooped up sand mollusks and rocks and hurled them against cliffs On a slope above the shoreline lead study author Ricardo Ramalho right inspects a hardened mishmash of debris or conglomerate Kim Martineau Tsunami expert Bill McGuire a professor emeritus at University College London who was not involved in the research said the study provides robust evidence of megatsunami formation and confirms that when volcanoes collapse they can do so extremely rapidly Based on his own work McGuire s says that such megatsunamis probably come only once every 10 000 years Nonetheless he said the scale of such events as the Fogo study testifies and their potentially devastating impact makes them a clear and serious hazard in ocean basins that host active volcanoes Ramalho cautions that the study should not be taken as a red flag that another big collapse is imminent here or elsewhere It doesn t mean every collapse happens catastrophically he said But it s maybe not as rare as we thought In the early 2000s other researchers started publishing evidence that the Cape Verdes could generate large tsunamis Others have argued that Spain s Canary Islands have already done so Simon Day a senior researcher at University College London has sparked repeated controversy by warning that any future eruption of the Canary Islands active Cumbre Vieja volcano could

    Original URL path: http://www.ldeo.columbia.edu/news-events/signs-ancient-megatsunami-could-portend-modern-hazard (2015-10-19)
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  • Strategic Plan | Lamont-Doherty Earth Observatory
    of more than 600 scientists postdoctoral fellows graduate students and administrative staff Our scientists are known throughout the international scientific community for their innovation collegiality and entrepreneurial spirit The Observatory is a core component of Columbia University s Earth Institute which brings together people and tools to address some of the world s most challenging problems from climate change and environmental degradation to poverty disease and the sustainable use of resources Our Vision Lamont Doherty has been a leader in the study of our planet since its founding 65 years ago Today Observatory scientists continue the institution s long tradition of addressing important questions in the Earth and planetary sciences Our focus for the coming decade is on deepening our impact exploring new research areas of global relevance and continuing our culture of excellence Our Strategic Plan outlines an approach that will guide the Observatory over the next ten years in its two fold quest to remain at the forefront of research in basic Earth ocean and atmospheric sciences and to become a leading intellectual center in the integration of Earth human and environmental sciences to support and promote sustainability in a rapidly changing world Our Research Initiatives The Earth system is dynamic involving interactions within and among the solid Earth ocean cryosphere and atmosphere including processes that influence and are influenced by life Humans are now altering the basic functioning of Earth systems to such a degree that we must address the problem of sustaining a habitable planet In the next decade Lamont Doherty will continue to pursue fundamental scientific research on the most pressing and relevant questions concerning Earth processes Our scientists are committed to supporting the three major core strengths that provide the foundation upon which all of the Observatory s interdisciplinary work rests These areas are

    Original URL path: http://www.ldeo.columbia.edu/about-ldeo/strategicplan (2015-10-19)
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  • Climate Change Leaves Its Mark on the Sea Floor? Maybe Not, Study Says | Lamont-Doherty Earth Observatory
    ages The idea that we might be able to read climate history in the sea floor is exciting but while rising magma likely is modulated by changes in sea level the claim that climate determines abyssal hill spacing doesn t match observations from all the world s oceans say the authors of a new paper published in this week s journal Science Jean Arthur Olive the lead author of the new study and a post doctoral research scientist at Lamont Doherty Earth Observatory and his co authors argue that the fabric of the sea floor is better explained by faults that form offsetting the crust as the plates pull apart The authors combined sea floor observations with recently developed models of mid ocean ridge dynamics to test the climate theory from several angles and found that even large fluctuations in melt supply at the height of ice ages and warm periods didn t affect the fault process shaping the sea floor Physical signals of the changing pressure of rising and falling sea level on the ocean floor may still be present but those signals are more likely to be picked up in the thickness of the plate the authors say The new paper is the first to explain the characteristic spacing of abyssal hills quantitatively as a function of seafloor spreading rate within a single theoretical framework That texture matters because it influences ocean currents which influence how ocean water mixes and flows The Snickers Bar Experiment To visualize what happens at the mid ocean ridge try this experiment a favorite of Lamont Doherty geophysicist and research professor Roger Buck a co author of the new paper Take a Snickers bar with both hands and try to pull it apart You ll see that the hardened outer shell of chocolate cracks while the gooey middle stretches As you pull on the candy bar stress builds up and the chocolate shell weakens finally cracking at the weakest points If you were to inject molten chocolate between the gooey center and the outer shell simulating magma at the mid ocean ridges the molten chocolate would flow into those cracks as soon as they formed reducing the stress We re arguing that it s pretty much the same process Olive said You re adding melt from below If you don t have a lot of melt being supplied to the ridge you ll see lots of faults The big faults develop and grow and move to the side with the spreading of the plates while melted mantle intrudes At some point too much energy is required for the faults to continue to grow a new fault forms near the ridge and a new hill is created Atlantic Hills vs Pacific Hills The visual difference in the spacing and size of abyssal hills along the Atlantic and Pacific mid ocean ridges first raised questions in the authors minds about the climate paper At the Mid Atlantic Ridge where less magma is produced you ll

    Original URL path: http://www.ldeo.columbia.edu/news-events/climate-change-leaves-its-mark-sea-floor-maybe-not-study-says (2015-10-19)
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  • At Sea with the Marcus G. Langseth | Lamont-Doherty Earth Observatory
    Videos Previous Years You are here Home News Events At Sea with the Marcus G Langseth October 15 2015 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 about sediments subduction zones and other geologic features The Langseth s seismic capabilities help researchers generate 2D and 3D maps of the Earth below the seafloor and better understand the dynamics of tectonic plates our climate and other Earth systems Learn more about the Langseth and its recent expeditions Scientists on the Langseth sailed off the U S East Coast last summer to map the seafloor land long ago reclaimed by sea rise In 2014 research from an earlier cruise was published showing that the volcanic plumbing at mid ocean ridges goes far deeper than previously thought Scientist Jim Gaherty wrote from a 2013 cruise into the remote Pacific Ocean to study tectonic plates Pratigya Polissar and others reported from a 2012 expedition in the central

    Original URL path: http://www.ldeo.columbia.edu/news-events/sea-marcus-g-langseth (2015-10-19)
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  • Melting Ice Sheets, Suntanned Rocks and an Award-Winning Postdoc | Lamont-Doherty Earth Observatory
    was and how much its melting contributed to sea level rise Blue lakes and black lakes When you look at aerial photos of Greenland you ll notice lakes near the edge of the ice sheet that are either grey blue or black Young saw those lakes and recognized a new way to measure the history of the expanding and retreating Greenland ice sheet He is currently co leading a four year project financed by the National Science Foundation that will use sediment cores from those lakes to determine when their catchment basins were covered by ice On the margin of the Greenland Ice Sheet lakes currently receiving meltwater from the ice sheet appear light blue or gray lake that do not appear black Source Google Earth When an ice sheet overlaps a lake s catchment basin the water flowing into the lake leaves a layer of minerals on the lake floor The grey lakes are those still receiving mineral laden water from the ice sheet When the catchment basin is ice free organic material dominates the lake and the lake appears black Scientists can take a sediment core from the bottom of a lake date the sediment layers and determine when the lake was receiving meltwater from the ice sheet based on the mineral content of each layer Pairing that information with mapping of each catchment basin under the current ice sheet they can reconstruct the changing size of the ice sheet over time Ice sheet modelers will then use that data to gauge sea level rise tied to the melting Greenland ice sheet through history Because the Greenland ice sheet is entirely on land rather than floating any melting adds to sea level rise Measuring the suntan on a rock The suntan on a rock method provides a different way of tracking the advance and retreat of glaciers Of course this isn t a suntan in the traditional sense When rocks are exposed to the atmosphere they are bombarded with cosmic ray neutrons the same neutrons raining down on all of us right now day and night In quartz a mineral commonly found in Greenland s rocks those neutrons create isotopes including beryllium 10 and carbon 14 Scientists know how quickly the isotopes form in rock and how quickly they decay so they can tell how long the rocks have been exposed since they were last covered by an ice sheet By comparing the fast decaying carbon 14 which has a half life of about 5 730 years and much slower decaying beryllium 10 with a half life closer to 1 4 million years they can also tell if the rocks were exposed in the past covered by an ice sheet and re exposed The process is called cosmogenic dating Joerg Schaefer who heads the Cosmogenic Nuclide Group at Lamont puts Young s skills and accomplishments into perspective Young was hired at Lamont to bring in Arctic glacier and geology expertise that is normally found well above his career

    Original URL path: http://www.ldeo.columbia.edu/news-events/melting-ice-sheets-suntanned-rocks-and-award-winning-postdoc (2015-10-19)
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