News
The year is 150 CE. It’s a humid summer day in Muyil, a coastal Mayan settlement nestled in a lush wetland on the Yucatan Peninsula. A salty breeze blows in from the gulf, rippling the turquoise surface of a nearby lagoon. Soon, the sky darkens. Rain churns the water, turning it dark and murky with stirred-up sediment. When the hurricane hits, it strips leaves off the mangroves lining the lagoon’s sandy banks. Beneath the tumultuous waves, some drift gently downward into the belly of the sinkhole at its center.
Nearly two millennia later, a team of paleoclimatologists have used sediment cores taken from Laguna Muyil’s sinkhole to reconstruct a 2,000-year record of hurricanes that have passed within 30 kilometers of the site. Richard Sullivan of Texas A&M presented the team's preliminary findings this month at AGU’s Fall Meeting. The reconstruction shows a clear link between warmer periods and an increased frequency of intense hurricanes. Read More
Europe’s Great Famine of 1315–1317 is considered one of the worst population collapses in the continent’s history. Historical records tell of unrelenting rain accompanied by mass crop failure, skyrocketing food prices, and even instances of cannibalism. These written records strongly suggest Europe’s Great Famine was caused by several years of devastating floods that began in 1314, but they can’t tell us how this flooding compares to historic averages, or its full geographical extent.
Now, new research using tree ring records confirms the historical data, showing the years of the Great Famine were some of Europe’s wettest. A team of researchers from the Lamont-Doherty Earth Observatory and Columbia University quantified the extent of Great Famine flooding and found the years 1314, 1315, and 1316 were the fifth-wettest sequence of summers on record over a 700-year period. Read More
About 400 million people could be at risk for flooding by the end of the century should the Greenland ice shelf continue to melt at its current pace, according to a new study.
The ice shelf, one of Earth's largest, is widely considered to be the largest annual contributor of water into the ocean, and it's expected to continue to be a major contributor to global sea-level rise in the future, according to the study, published in the journal Nature on Tuesday. Read More
The 2019 Fall AGU meeting is next week and there will be many presentations from our PaleoDynamics Group, affiliated colleagues, and collaborators. Below is a chronological list of all our activities.
In addition to the individual presentations, Smerdon and Ed Cook will also be convening the Climate of the Common Era session with co-coveners Kevin Anchukaitis and Kim Cobb. This will be the 10th anniversary of the session and also mark the last time that the current group of conveners will convene the session. Several retrospective talks will kick off the session to commemorate its 10th anniversary: Anchukaitis et al., Otto-Bliesner et al., and Evans et al. These will be part of the two oral session on Thursday, 12 December 2019, from 8-10 and 10:20-12:20 and the poster session will be from 13:40-18:00 on the same day.
MONDAY
Jason Smerdon, Seung Hun Baek, George-Costin Dobrin, Jacob Naimark, Edward Cook, Benjamin Cook, Richard Seager, Mark Cane, A Paleoclimatic Context for the European Great Famine of 1315-1317, Monday, 9 December 2019, 8:00 - 12:20, PP11C-1399, Moscone South - Poster Hall
Benjamin Cook, Park Williams, David Stahle, Edward Cook, Dorian Burnette, Cold and Warm Season Contributions to Major Drought Events in the North American Seasonal Precipitation Atlas, Monday, 9 December 2019, 8:00 - 12:20, PP11C-1404, Moscone South - Poster Hall
Serena Scholz, Richard Seager, Mingfang Ting, Yochanan Kushnir, Centennial Timescale Variability in Euro-Mediterranean Hydroclimate Since the Little Ice Age, Monday, 9 December 2019, 8:00 - 12:20, GC11G-1124, Moscone South - Poster Hall
TUESDAY
Daniel Bishop, Park Williams, Ron Miller, Benjamin Cook, Richard Seager, Quantifying the drivers of regional hydroclimate change from the fall-season North Atlantic Subtropical High, Tuesday, 10 December 2019, 8:00 - 12:20, A21J-2741, Moscone South - Poster Hall
Seung Hun Baek, Jason Smerdon, Mingfang Ting, Yochanan Kushnir, Richard Seager, Untangling Observed Atlantic Multidecadal Variability, Tuesday, 10 December 2019, 14:55 - 15:10, OS23A-06, Moscone West - 2002, L2
Mingfang Ting, Richard Seager, Cuihua Li, Future Summer Drying in the Midwestern United State in CMIP5 Models and the Role of Midlatitude Storm Tracks, Tuesday, 10 December 2019, 17:00 - 17:15, A24J-05, Moscone West - 3002, L3
Winslow Hansen, Park Williams, Rupert Seidl, Global hotspots of forests primed to climate variability, Tuesday, 10 December 2019, 17:15 - 17:30, B24C-06, Moscone West - 3007, L3
Edward Cook, Mark Cane, Jason Smerdon, Experimental Gridded Tree-Ring Reconstruction of Indo-Pacific Winter Sea Surface Temperatures, Tuesday, 10 December 2019, 17:30 - 17:45, GC24A-07, Moscone West - 2005, L2
WEDNESDAY
Alan Huston, Nicholas Siler, Gerard Roe, Erin Pettit, Nathan Steiger, Understanding Drivers of Glacier Length Variability Over the Last Millennium, Wednesday, 11 December 2019, 8:00 - 12:20, GC31G-1269, Moscone South - Poster Hall
Edward Cook, Mukund Rao, Benjamin Cook, Maria Uriarte, Jonathan Palmer, Upmanu Lall, Rosanne D'Arrigo, Connie Woodhouse, Jun Jian, Peter Webster, A Wetter Brahmaputra River with Greater Flood Risk, Wednesday, 11 December 2019, 9:15 - 09:30, GC31A-06, Moscone West - 2007, L2
Bor-Ting Jong, Mingfang Ting, Richard Seager, Assessing ENSO summer teleconnections and impacts on North America in GCMs, Wednesday, 11 December 2019, 17:15 - 17:30, A34E-06, Moscone West - 3000, L3
THURSDAY
Kevin Anchukaitis, Kim Cobb, Edward Cook, Jason Smerdon, A retrospective on 10 years of the Climate of the Common Era Session at AGU, Thursday, 12 December 2019, 8:00 - 08:15, Moscone West - 2004, L2
Ernesto Tejedor Vargas, Nathan Steiger, Jason Smerdon, Roberto Serrano-Notivoli, Mathias Vuille, Hydroclimatic Response to Volcanic Eruptions over the Last Millennium might be muted in the LME CESM, Thursday, 12 December 2019, 9:30 - 09:45, PP41A-06, Moscone West - 2004, L2
Park Williams, Edward Cook, Connie Woodhouse, David Meko, Benjamin Cook, Kasey Bolles, Scott Steinschneider, A 1200-year perspective on modern high- and low-frequency variability in California's Sierra Nevada cold-season precipitation using tree rings, Thursday, 12 December 2019, 10:50 - 11:05, PP42B-03Moscone West - 2004, L2
Arianna Varuolo-Clarke, Jason E Smerdon, Park Williams, Investigating Opposing 20th-Century Precipitation Trends in Chile and Argentina using Observations and Models, Thursday, 12 December 2019, 13:40 - 18:00, GC43E-1442, Moscone South - Poster Hall
Roberto Serrano-Notivoli, Ernesto Tejedor Vargas, Pablo Sarricolea, Oliver Meseguer-Ruiz, Mathias Vuille, Magdalena Fuentealba, Martin de Luis, Hydroclimatic variability in central Chile since the 13th century, Thursday, 12 December 2019, 13:40 - 18:00, GC43E-1443,Moscone South - Poster Hall
Sonali Shukla McDermid, Benjamin Cook, Martin Gerard De Kauwe, Justin Mankin, Jason E Smerdon, Park Williams, Richard Seager, Michael Puma, Igor Aleinov, Maxwell Kelley, Larissa Nazarenko, Disentangling the regional climate impacts of competing vegetation responses to elevated [CO2], Thursday, 12 December 2019, 17:30 - 17:45, H44A-07, Moscone West - 3014, L3
Trevor Harris, Bo Li, Jason Smerdon, Nathan Steiger, Naveen Narisetty, James Tucker, Testing The Exchangeability Of Two Ensembles Of Spatial Processes - Evaluating Proxy Influence In Assimilated Paleoclimate Reconstructions, Thursday, 12 December 2019, 13:40 - 18:00, PP43D-1636, Moscone South - Poster Hall
Kasey Bolles, Park Williams, Daniel Bishop, Edward Cook, Frequency and Trends of Central U.S. Flash Drought Occurrence since 1490, Thursday, 12 December 2019, 13:40 - 18:00, PP43D-1646, Moscone South - Poster Hall
Nicole K Davi, Rose Oelkers, Rosanne D'Arrigo, Mukund Rao, Laia Andreu-Hayles, Edward Cook, Caroline Leland, Jessica Geary, Improved Central Asian Temperature from Blue Intensity Reflectance of Tree Rings, Thursday, 12 December 2019, 13:40 - 18:00, PP43D-1651, Moscone South - Poster Hall
Benjamin Cook, Katherine Marvel, Park Williams, Climate Change Projections of Drought in the CMIP6 Archive, Thursday, 12 December 2019, GC42E-03, Moscone South - eLightning Theater III
FRIDAY
Mariano Morales et al., The South American Drivers of Megadroughts and Pluvials over the Past 600 years, Friday, 13 December 2019, 9:15 - 09:30, GC51A-06, Moscone West - 2010, L2
Nathan Steiger, Jason Smerdon, Park Williams, Coupled megadrought risk in North and South America, Friday, 13 December 2019, 9:30 - 09:45, GC51A-07, Moscone West - 2010, L2
Jennifer Balch, Park Williams, Bethany Bradley, John Abatzoglou, Paulo Brando, The human imprint on modern forest fire, Friday, 13 December 2019, 10:50 - 11:05, B52C-03, Moscone West - 3001, L3
Aaron Putnam, Joerg Schaefer, Summer Rupper, Edward Cook, Karma Tsering, Chhimi Dorji, David Putnam, Nicolas Young, Tshewang Rinzin, Pashupati Sharma, Ananta Gajurel, Paul Krusic, Peter Strand, Laura Mattas, Chronology of past mountain glacier fluctuations in the eastern Himalaya as context for industrial-age glacier recession, Friday, 13 December 2019, 11:05 - 11:20, GC52B-04, Moscone West - 2003, L2
Sha Zhou, Park Williams, Alexis Berg, Benjamin Cook, Yao Zhang, Stefan Hagemann, Ruth Lorenz, Sonia Seneviratne, Pierre Gentine, Land-atmosphere feedbacks exacerbate concurrent soil drought and atmospheric aridity, Friday, 13 December 2019, 11:50 - 12:05, GC52A-07, Moscone West - 2005, L2
The way that plants and trees respond to a warming climate and increasing levels of atmospheric CO2 has a significant impact on how they use water.
But will this leave more or less freshwater available for societies to use? That millions of people suffer from life-threatening water stresses in the current climate tells us that the answer to this question really matters.
Our new study, published in Nature Geoscience, attempts to shed light on this complicated picture.
Justin Mankin, a former postdoctoral fellow in the Paleodynamics Lab, has published a paper in Nature Geosciences on the role of plants in future freshwater availability. Plants are expected to generate more global-scale runoff under increasing atmospheric carbon dioxide concentrations by reducing evapotranspiration. Recent studies using Earth System Models from phase 5 of the Coupled Model Intercomparison Project ostensibly reaffirm this result, further suggesting that plants will ameliorate the dire reductions in water availability projected by other studies. Justin's work complicates this narrative by showing that projected plant responses directly reduce future runoff across vast swaths of North America, Europe and Asia because of additional vegetation growth and longer and warmer growing seasons. These runoff declines occur despite reductions in evapotranspiration and the efficiency with which plants use water, even in regions with increasing or unchanging precipitation. These results are strengthened even further when the model results are constrained using regional-scale observations of evapotranspiration. The main conclusion of the work is that terrestrial vegetation plays a large and unresolved role in shaping future regional freshwater availability, one that will not ubiquitously ameliorate future warming-driven surface drying.
Selected News Coverage:
The amount of greenhouse gases being emitted into Earth's atmosphere has reached such a high level that it will take major changes around the world to mitigate the effects on climate change, experts say.
Greenhouse gasses such as carbon dioxide, which trap the sun's heat, are the "most significant driver of observed climate change since the mid-20th century," according to the U.S. Environmental Protection Agency. Read More
With experts warning that the global climate crisis is becoming more and more dire, scientists and environmental activists say they are turning to the public to help effect change before it's too late.
The planet is emitting nine gigatons of carbon every year, and that amount increases annually, Jason Smerdon, a climate scientists for Columbia University's Lamont Doherty Earth Observatory, told ABC News. By other estimates, the amount could be more than 30 gigatons a year. Read More
Note: The estimates for carbon emissions in the above article are different because of different unit choices, not because of differences in the estimates. For instance, Smerdon is quoted as saying that humans emit ~9 GT of C per year, which is 9*3.667 or ~33 GT of CO2 equivalent emissions. 9 GT C per yer is therefore equal to the 33 GT of CO2 equivalent emissions per year that is reported in provided link to "other estimates."
Note 2: Just for fun, consider the following description of a GT provided in the Chapter 7 Back-of-the-Envelope calculation from Mathez and Smerdon: A gigaton (Gt) is 1015 grams, or 1 billion metric tons, which is hard to imagine. To put it in perspective, consider that a Nimitz-class aircraft carrier, the largest warship ever built, weighs a measly 88,000 metric tons under full load. A single gigaton would therefore amount to about 11,364 of these warships! If you prefer an example from land, the Great Pyramid of Giza is estimated to weigh about 5.9 million metric tons, requiring 170 such pyramids to equal just 1 gigaton. In either case, these quantities put into perspective the massiveness of a single gigaton...
Sloan Coats visited Lamont to give the OCP Seminar on September 20th. The title of his talk was A Story of Mega Droughts: New methods that highlight novel pathways for solid earth-climate coupling (see his talk abstract below). Sloan finished his PhD in the PaleoDynamics Lab in 2015 and is starting a tenure track faculty position at the University of Hawaii this fall (he was previously a Staff Scientist at the Woods Hole Oceanographic Institution). Sloan's visit was an occasion to gather lab members and collaborators for an evening dinner. Hun Baek, Arianna Varuolo-Clarke, and Park Williams joined from Lamont, while Ernesto Tejedor and Natalia Ruiz Menal, our collaborators on the NSF PIRE project, were able to join from the University of Albany (see picture).
A Story of Mega Droughts: New methods that highlight novel pathways for solid earth-climate coupling
Abstract: A long standing question is what role natural external forcings, largely in the form of volcanic eruptions and cycles of solar output, play in driving climate variability on longer than decadal timescales. During relatively stationary climate states like the mid Holocene to present day, climate models and paleoclimate reconstructions suggest little role for these external forcings in driving hydroclimate variability. Herein, novel machine learning based methods that identify drought in three-dimensional space-time (latitude, longitude, and time) are applied to climate model simulations of the last millennium over North America. Analyzing the spatiotemporal characteristics of the most persistent and severe droughts in these simulations provides important insights into how external forcings can impact drought—principally through interactions of volcanic eruptions and internal modes of coupled climate variability.
The Lamont-Doherty Earth Observatory is now accepting applications for 2020 Lamont Postdoctoral Fellowships (deadline is November 11th, 2019). The Earth Institute is also accepting applications for 2020 Earth Institute Postdoctoral Fellowships (deadline is October 30th, 2019). Our lab has mentored postdocs from both of these programs and we welcome your interest in pursuing research that you independently develop and pursue. Contact Prof. Jason Smerdon if you would like more information on working in our lab as a Lamont or EI postdoc.
When Jason Smerdon opened up a retirement account as a postdoctoral fellow a decade and a half ago, he gravitated toward socially responsible stock funds, despite the possibility of weaker returns. He figured his ideals were more important than investment performance.
Fast forward 15 years, and his investment philosophy is no longer as black and white. Read More
Multidecadal “megadroughts” were a notable feature of the climate of the American Southwest over the Common Era, yet we still lack a comprehensive theory for what caused these megadroughts and why they curiously only occurred before about 1600 CE. Nathan Steiger, a research scientist in the PaleoDynamics Lab, has published a paper using the Paleo Hydrodynamics Data Assimilation (PHYDA) product, in conjunction with radiative forcing estimates, to determine the causes of megadroughts in the American Southwest. He and coauthors report strong evidence that these droughts were driven by unusually frequent and cold central tropical Pacific sea surface temperature (SST) excursions in conjunction with anomalously warm Atlantic SSTs and a locally positive radiative forcing. This assessment of past megadroughts provides the first comprehensive theory for the causes of megadroughts and their clustering, particularly during the Medieval era. The work also provides the first paleoclimatic support for the prediction that the risk of American Southwest megadroughts will markedly increase with global warming (see here and here).
The PHYDA was developed by Nathan as a postdoctoral scientist in the PaleoDynamics Lab and is available here. His megadrought paper can be found here.
Selected New Coverage:
Widespread summer droughts across the contiguous UnitedStates (pan-CONUS droughts) pose unique challenges because of their potential to strain multiple water resources simultaneously and the significant financial damages that they impose. For example, pan-CONUS droughts in 1988 and 2012 cost an estimated $40 and $30 billion, respectively. Hun Baek, a graduate student in the PaleoDynamics Lab, has studied these droughts in detail, first using atmospheric model simulations to study the causes of these droughts over the last ~150 years. In a new paper, Hun has now provided a millennium-length perspective on the causes of pan-CONUS droughts and shown that the results from his paleoclimatic analysis agree well with his model findings that focused on the last century and a half. His principal finding is that La Niña events in the tropical Pacific are the principal oceanic influence on these droughts, while variability in the Atlantic has not played a significant role. These results are important for predictions of pan-CONUS droughts, and for determining how the occurrence of these droughts may change in the future due to increases in greenhouse gas emissions. An important methodological milestone of this study is the first application of the Paleo Hydrodynamics Data Assimilation (PHYDA) product for use in a paleodynamics context. The PHYDA was developed by Nathan Steiger as a postdoctoral scientist in the PaleoDynamics Lab. The abstract of Hun's paper is given below, while his paper can be found here.
Abstract: We examine oceanic drivers of widespread droughts over the contiguous US (herein pan‐CONUS droughts) during the Common Era in what is one of the first analyses of the new Paleo Hydrodynamics Data Assimilation product (PHYDA). The canonical understanding of oceanic influences on North American hydroclimate suggests that pan‐CONUS droughts are forced by a contemporaneous cold tropical Pacific Ocean and a warm tropical Atlantic Ocean. We test this hypothesis using the paleoclimate record. Composite analyses find a robust association between pan‐CONUS drought events and cold tropical Pacific conditions, but not with warm Atlantic conditions. Similarly, a self‐organizing map analysis shows that pan‐CONUS drought years are most commonly associated with a global sea surface temperature pattern displaying strong La Niña and cold AMO conditions. Our results confirm previous model‐based findings for the instrumental period and show that cold tropical Pacific Ocean conditions are the principal driver of pan‐CONUS droughts on annual timescales.
The website for our PIRE CREATE project has been launched. Check it out!
Take a look at that syllabus your teacher handed out at the start of this year. If your professor teaches at one of the 12 schools, departments, or locations that have been certified through the Sustainable Leaders Network’s Workplace Certification, that syllabus is most likely printed on 100 percent recycled paper. And that business card you got from a professor in the School of Nursing? It’s probably made up of at least 30 percent postconsumer waste content.
The Sustainable Leaders Network was created in 2016 alongside University President Lee Bollinger’s announcement of Columbia’s first set of sustainability principles. The group is composed of voluntary representatives from across Columbia’s schools and departments with the intention of being a metrics-driven tool to help accomplish the University’s sustainability goals. Read more