Tag Archive for Ellen Thomas

Thomas’s Microfossil, Climate Change Research Published in 2 Journals

Ellen Thomas

Ellen Thomas

Ellen Thomas, the University Professor in the College of Integrative Sciences, research professor of earth and environmental science, is the co-author of two recently published papers. They include:

Microfossil evidence for trophic changes during the Eocene–Oligocene transition in the South Atlantic (ODP Site 1263, Walvis Ridge),” published in Climate of the Past, Volume 11, pages 1249–1270 in September 2015 and “Changes in benthic ecosystems and ocean circulation in the Southeast Atlantic across Eocene Thermal Maximum 2,” published in the journal Paleoceanography, Volume 30, pages 1059-1077 in August 2015.

“Microfossil evidence” describes changes in organisms living in the oceans during a major change in the earth’s climate, a period of global cooling about 33.7 million years ago, when the Antarctic ice sheet first became established. The seven co-authors are all women, including former Wesleyan graduate student Raquel Fenero.

The researchers examined the biotic response of calcareous nannoplankton to environmental and climatic changes during the Eocene–Oligocene transition at Ocean Drilling Program (ODP) Site 1263 (Walvis Ridge, southeast Atlantic Ocean). During this time interval, global climate, which had been warm under high levels of atmospheric CO2 during the Eocene, transitioned into the cooler climate of the Oligocene.

In the Paleoceanography article, Thomas and her co-authors describe changes in benthic ecosystems in the oceans during a short period of global warming about 53.7 million years ago, and the effects of loss of oxygen and ocean acidification. The researchers include climate and geochemical modeling to indicate that changes in ocean circulation due to warming triggered more profound effects on living organisms at some depths than at other depths, and that the response of life forms to global warming (including feedback effects) thus may be complex. This article is the result of research done during Thomas’s stay as Leverhulme Visiting Professor at the University of Bristol in the United Kingdom, where she co-supervised graduate student Suzy Jennions.

“Our combined ecological and modeling analysis illustrates the potential role of ocean circulation changes in amplifying local environmental changes and driving temporary, but drastic, loss of benthic biodiversity and abundance,” Thomas said.

NSF Supports Thomas’s Study on the Impact of Rapid Carbon Emissions on Global Climate

Ellen Thomas

Ellen Thomas

Ellen Thomas, the University Professor in the College of Integrative Sciences, received a grant in August from the National Science Foundation to support her research on “Evaluating Deep-Sea Ventilation and the Global Carbon Cycle during early Paleocene Hyperthemals.”

The $105,000 award is part of a combined $619,000 grant shared with Yale University and the University of Texas at Arlington.

Rapid, short-term global warming events in the Early Paleogene (~65-45 million years ago) were caused by massive greenhouse gas release into the ocean-atmosphere system. These warming events, called hyperthermals, had far-reaching effects on the evolution of life on Earth, ecosystems and the carbon cycle. The most extreme of these events was the Paleocene-Eocene Thermal Maximum (~55.5 million years ago). Hyperthermals resemble what could happen during anthropogenic climate change, and provide analogs for the effects of greenhouse gas emissions and their long-term effects on life on Earth.

By testing earth system interactions during the Paleogene hyperthermals, this interdisciplinary project will provide new insight into the impact of rapid carbon emissions on global climate—carbon cycle feedbacks and extremes in climate.

In this three-year collaborative project, new biotic, isotopic and trace element proxies will be integrated with existing data into a state-of-the-art, high-resolution, comprehensive earth system model to test the hypothesis that deep-sea ventilation released a massive amount of carbon from the refractory dissolved organic matter (DOM) pool during hyperthermal events, increasing atmospheric CO2 levels, thus amplifying climate change through carbon-cycle feedback.

“We will investigate the environmental response (e.g., ocean acidification and deoxygenation) and its impact on pelagic ecosystem structure for three Paleogene hyperthermals with different magnitude and duration,” Thomas explained. “The project will focus on a key mechanism involving remineralization of organic matter and oxidation of the DOM pool in the ocean, with potentially major implications for future climate evolution.”

Thomas Authors 4 Papers on Environmental Change

Ellen Thomas

Ellen Thomas

Ellen Thomas, research professor of earth and environmental sciences, is the co-author of four recenty-published papers. They include:

Deep-sea benthic foraminiferal turnover during the early middle Eocene transition at Walvis Ridge (SE Atlantic),” published in Palaeogeography, Palaeoclimatology, Palaeoecology, Issue 417: pages 126-136, January 2015. The paper’s co-author, Silvia Ortiz, was a PhD student at the University of Zaragoza, and spent several months at Wesleyan working with Thomas.

Thomas Uses CT Scans, Computer-Aided Visualizations to Study and Teach Microfossils

Ellen Thomas, research professor of earth and environmental science, holds two samples of microfossils that were printed on a 3-D printer at the American Museum of Natural History. The printed fossil models are about 8,000 times bigger than the actual limestone fossils.  Ellen Thomas holds two planktonic forms which lived closer to the surface of the water. At left is Hantkenina alabamensis, which lived when the world was warm, and went extinct at the time of formation of the Antarctic ice cap about 33.7 million years ago. At right is Globigerinella siphonifera. It lives in the subtropics today, in open ocean. "When it's alive, it has spines and protoplasm inside and along the spines," she said.

Ellen Thomas, research professor of earth and environmental science, holds two samples of microfossils that were printed on a 3-D printer at the University of Iowa. The printed fossil models are about 8,000 times bigger than the actual limestone fossils. These planktonic forms lived closer to the surface of the water. At left is Hantkenina alabamensis, which lived when the world was warm, and went extinct at the time of formation of the Antarctic ice cap about 33.7 million years ago. At right is Globigerinella siphonifera. It lives in the subtropics today, in open ocean. “When it’s alive, it has spines and protoplasm inside and along the spines,” she said. (Photos by Olivia Drake)

This slide contains 65 different microfossil specimens taken from an ocean drilling site in the eastern Indian Ocean. Some are estimated to be 55.8 millions years old and span a duration of 170,000 years. During this time, there was an extinction of deep-sea benthic foraminifera which may have been caused by rapid global warming.

This slide contains more than 300 microfossil specimens from an ocean drilling site in the eastern Indian Ocean. These are estimated to be 55.8 millions years old, and lived during a period of extreme global warming with a duration of 170,000 years. At the beginning of this warm period, there was a mass extinction of deep-sea benthic foraminifera, which may have been caused by the rapid global warming and ocean acidification.

#THISISWHY

Research Professor Ellen Thomas grasps a glass-enclosed sample of hundreds of microfossils, each a white fleck of limestone barely visible to the human eye.

“The first time students look at these they say, ‘they all look the same to me,’ but in reality, they are all have very different shapes,” Thomas says. “Even under a microscope, it can be difficult for a new eye to see the differences, but each species has its own shape; some have a much more open, light structure because they lived floating in the oceans close to the surface. Others have denser shells and lived on the bottom of the ocean, or within the mud. And each one can tell us, in its chemical make up, what the environmental conditions were like at the time that they lived and built their shells.”

By studying and analyzing microfossils, Thomas and fellow scientists are able to explore aspects of climate change on a variety of timescales,

Studies by Varekamp, Thomas Published in Paleoceanography

varekamp

Joop Varekamp

Ellen Thomas

Ellen Thomas

Wesleyan faculty Joop Varekamp and Ellen Thomas are among the authors of a paper on rates of sea-level rise along the eastern U.S. seaboard titled “Late Holocene sea level variability and Atlantic Meridional Overturning Circulation,” published in the journal Paleoceanography, Volume 29, Issue 8, pages 765–777 in August 2014. Varekamp is the Harold T. Stearns Professor of Earth Science, professor of earth and environmental sciences and professor of environmental studies. Thomas is research professor of earth and environmental sciences at Wesleyan, and also a senior research scientist in geology and geophysics at Yale University.

Ellen Thomas discovered that microfossils, such as this  foraminifera fossil, reveal that warm oceans had less oxygen.

Ellen Thomas discovered that microfossils, such as this foraminifera fossil, reveal that warm oceans had less oxygen.

Pre-20th century sea level variability remains poorly understood due to limits of tide gauge records, low temporal resolution of tidal marsh records, and regional anomalies caused by dynamic ocean processes, notably multidecadal changes in Atlantic Meridional Overturning Circulation (AMOC). In the study, Varekamp and Thomas examined sea level and circulation variability along the eastern United States over the last 2,000 years, using a sea level curve constructed from proxy sea surface temperature records from Chesapeake Bay, and 20th century sea level-sea surface temperature relations derived from tide gauges and instrumental sea surface temperatures.

Thomas also is a co-author of a paper titled ‘I/Ca evidence for upper ocean deoxygenation during the PETM‘ published in the Paleoceanography, October 2014.

In this paper, Thomas suggests that the Paleocene-Eocene Thermal Maximum (PETM), a potential analog for present and future global warming, may help in such forecasting future deoxygenation and its effects on oceanic biota. Forecasting the geographical and bathymetric extent,

Thomas’s Paper Published in Paleoceanography

The deep-sea benthic foram Aragonia velascoensis went extinct about 56 million years ago as the oceans rapidly acidified. (Photo by Ellen Thomas)

The deep-sea benthic foram Aragonia velascoensis went extinct about 56 million years ago as the oceans rapidly acidified. (Photo by Ellen Thomas)

Ellen Thomas, research professor of earth and environmental sciences, is the author of a paper titled “Rapid and sustained surface ocean acidification during the Paleocene-Eocene Thermal Maximum,” published in Paleoceanography, May 2014. 

In this paper Thomas and her colleagues document that ocean acidification of the surface ocean not only occurred during past times of global warming and high CO2 levels, but also by how much — about 0.3 pH units. The group studied planktic foraminifers from a drill site in the North Pacific.

Thomas’ study has been highlighted in a press release from Columbia University and also on Phys.org.

Thomas’s Paper Published in Nature Geoscience

Ellen Thomas

Ellen Thomas

Ellen Thomas, research professor of earth and environmental sciences, is the co-author of a paper titled “Carbon Sequestration during the Palaeocene–Eocene Thermal Maximum by an Efficient Biological Pump,” published in the April 2014 edition of Nature Geoscience.

In the paper, Thomas explains how ocean-dwelling bacteria may have vacuumed up carbon and halted a period of extreme warmth some 56 million years ago. The finding suggests how Earth might once have rapidly reversed a runaway greenhouse effect.

Its effect on global oceanic productivity is controversial. In the paper, Thomas and her colleagues present records of marine barite accumulation rates that show distinct peaks during this time interval, suggesting a general increase in export productivity. The authors propose that changes in marine ecosystems, resulting from high atmospheric partial pressure of CO2 and ocean acidification, led to enhanced carbon export from the photic zone to depth, thereby increasing the efficiency of the biological pump. Higher seawater temperatures at that time increased bacterial activity and organic matter regeneration.

Gabriel Popkin ’03 wrote about Thomas’s research in a April 2014 article titled “Ocean Bacteria May Have Shut Off Ancient Global Warming” in Science News.

Varekamp, Thomas Author Chapters on Long Island Sound Reference Volume

Joop Varekamp and Ellen Thomas

Joop Varekamp and Ellen Thomas co-authored chapters in this new book on the Long Island Sound.

Joop Varekamp and Ellen Thomas are the authors of three chapters included in a reference volume for Long Island Sound. The book, Long Island Sound: Prospects for the Urban Sea, is published by Springer in 2013. Varekamp is the Harold T. Stearns Professor of Earth Science, professor of earth and environmental sciences, professor of environmental studies. Thomas is research professor of earth and environmental sciences.

Varekamp co-authored a chapter titled “Metals, Organic Compounds and Nutrients in Long Island Sound: Sources, Magnitudes, Trends and Impacts,” and another chapter titled “The Physical Oceanography of Long Island Sound.” Thomas co-authored a chapter titled “Biology and Ecology of the Long Island Sound.”

Varekamp and Thomas worked on the book for about six years.  The last comprehensive Long Island Sound book was published in the early 1970s.

“We hope that it will be the reference volume for Long Island Sound for some decades to come,” Varekamp said.

Thomas Wins Women Geoscientist Excellence Award

Ellen Thomas

Ellen Thomas

Ellen Thomas, research professor of earth and environmental sciences, was named the winner of the 2013 Association for Women Geoscientists Professional Excellence Award in the Academia category. This award recognizes exceptional women who have made distinguished contributions in their professions throughout their careers.

“The Award Committee was especially impressed with the breadth and depth of your professional accomplishments, your commitment to mentoring, and the emphasis you have placed on outreach and other service activities during your career,” wrote Aimee Scheffer, president of the AWG in Thomas’ award letter. “Congratulations and thank you for being a positive role model to current and future generations of women geoscientists.”

Thomas will receive the award during the Geological Society of America 2013-14 meeting in Denver, Colo.

 

 

 

Thomas Authors Papers, Book on Climate Change, Global Extinction

Book co-authored by Ellen Thomas.

Book co-authored by Ellen Thomas.

Ellen Thomas, research professor of earth and environmental sciences, is the co-author of “Surviving rapid climate change in the deep-sea during the Paleogene hyperthemals,” published in the June 4 issue of The Proceedings of the National Academy of Sciences, Vol. 110, No. 23. Read the paper’s abstract online here.

Thomas also is the co-author of “Paleoenvironmental changes during the Middle Eocene Climatic Optimum (MECO) and its aftermath: the benthic foraminiferal record from the Alano section (NE Italy),” published in the May 15 issue of Palaeogeography, Palaeoclimatology, Palaeoecology, 378, 22-35. Read the paper’s abstract online here.

She also co-authored a book titled, The Last Global Extinction (Mid-Pleistocene) of Deep-Sea Benthic Foraminifera (Chrysalogoniidae, Ellipsoidinidae, Glandulonodosariidae, Plectofrondiculariidae, Pleurostomellidae, Stilostomellidae), Their Late Cretaceous-Cenozoic History and Taxonomy, published by the Cushman Foundation for Foraminiferal Research. Read the book’s abstract online here.

Book Co-Authored by Thomas Receives Prose Award

Ellen Thomas

Ellen Thomas

A geology book featuring a chapter co-authored by Ellen Thomas received a PROSE Award from The American Publishers Awards for Professional and Scholarly Excellence in 2013.

Thomas is a research professor of earth and environmental sciences. She co-authored a chapter titled, “Carbon Isotope Stratigraphy,” in the book, The Geologic Time Scale 2012, published by Elsevier in July 2012.

The PROSE Awards annually recognize the very best in professional and scholarly publishing by bringing attention to distinguished books, journals, and electronic content in over 40 categories. Judged by peer publishers, librarians, and medical professionals since 1976, the PROSE Awards are extraordinary for their breadth and depth.

The book received honorable mention in the Multivolume Reference/Science category. See the full list of winners online here.