Studying global warming events from millions of years ago for insight into climate change
A team of scientists led by researchers at The University of Texas at Arlington is examining global warming events that happened millions of years ago in order to gain new insights into present-day climate change.
The National Science Foundation's Division of Ocean Sciences has awarded a $403,114 grant to Arne Winguth, UTA associate professor of earth and environmental sciences, for a three-year study titled "Evaluating Deep-Sea Ventilation and the Global Carbon Cycle during Early Paleogene Hyperthermals." Winguth is joined on the project by co-investigators Elizabeth Griffith, a UTA assistant professor of earth and environmental sciences, and his wife Cornelia Winguth, a lecturer in the same department.
The project focuses on the Early Paleogene, the period of time roughly 66 to 45 million years ago, when rapid, short-term global warming events, called hyperthermals, were caused by large amounts of greenhouse gases being released into the ocean-atmosphere system. Hyperthermals had far-reaching effects on the evolution of life of Earth, ecosystems and the carbon cycle.
"Hyperthermals resemble what could happen during anthropogenic or human-caused climate change, and provide analogs for the effects of greenhouse gas emissions and their long-term effects on life on Earth," Arne Winguth said. "By testing earth system interactions during the Paleogene hyperthermals, this interdisciplinary project will provide new insight into global climate-carbon cycle feedbacks and extremes in climate."
College of Science Dean Morteza Khaledi said that the project could help scientists better understand the processes which can lead to climate change and noted that it addresses global environmental impact, one of the core themes of UTA's Strategic Plan 2020: Bold Solutions | Global Impact.
"This is a great example of how studying the Earth's distant geological past can give us clues about things going on now, or things that can happen in the future," Khaledi said. "The integration of data and modeling being done in this project could yield important information about climate change."
The UTA team is collaborating with Ellen Thomas, a University Professor in the College of Integrative Sciences at Wesleyan University in Middletown, Conn., and Pincelli Hull, an assistant professor of geology and geophysics at Yale University.
The NSF project also includes an outreach component with Arlington Seguin High School. The Winguths gave a presentation at the school and led a field trip of Seguin students to the Perot Museum of Nature and Science in Dallas in early April 2016.
Arne Winguth and students from Seguin are meeting weekly to develop an outreach webpage and online educational tools on abrupt climate change related to the project. The goal of this part of the project is to enhance training in quantitative science for undergraduate and high school students from diverse backgrounds, he said.
The project involves the integration of new biotic, isotopic and trace element proxies with existing data into a state-of-the-art, high-resolution, comprehensive Earth system model, the researchers explained in the project's abstract.
"One hypothesis that we will be testing contends that a large amount of carbon was released from the ocean during these hyperthermal periods, which put a lot more CO2 into the atmosphere," Griffith said.
The researchers will test the hypothesis that deep-sea ventilation released a massive amount of carbon from the refractory dissolved organic matter pool during hyperthermal events, increasing atmospheric carbon dioxide levels and thus amplifying climate change through carbon-cycle feedback.
"From the geologic carbon isotope record we know that the Earth's carbon cycle underwent major changes, due to rapid releases of carbon dioxide and/or methane into the atmosphere," Cornelia Winguth said. "Many scientists are interested in studying these hyperthermal events as possible analogs for current and future carbon cycle and climate changes. We will compare new data from various deep-sea cores with the results of new, comprehensive climate model experiments in order to better understand possible causes of the hyperthermals, especially related to changes in the ocean."
"Primary productivity changes in the ocean and changes in the way organic material was remineralized or stored in deeper parts of the ocean might have had a strong impact on the carbon cycle."
The most extreme of the hyperthermal events during the Paleogene was the Paleocene-Eocene Thermal Maximum, which occurred about 56 million years ago. Past research has shown that the onset of the Paleocene-Eocene Thermal Maximum brought extreme changes in Earth's carbon cycle and ushered in a time of massive carbon injection into the ocean and atmosphere, and an increase in global temperatures of 5 to 8 °C.
The Paleocene-Eocene Thermal Maximum presents a good case study for global warming and large-scale input of carbon to the ocean and atmosphere, including ocean acidification, which is caused by the uptake of carbon dioxide from the Earth's atmosphere. Finding out the causes of these events could help scientists to better understand the specifics of the global warming now happening to the planet.
The project will blend data collection with advanced computer modeling. Griffith and students in her laboratory are analyzing sediments from ocean cores extracted from the Pacific and Atlantic Oceans decades ago and collecting data on the cores' composition. Information gained from this work will then be used by Arne and Cornelia Winguth in their computer modeling.
The Winguths are using a high-performance computer named "Yellowstone" which is located at the NCAR Wyoming Super Computer Center. The model they are applying and which runs on the Yellowstone supercomputer is the Community Earth System Model, which is a fully-coupled, global climate model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate states.
The research team will investigate the environmental response – ocean acidification and de-oxygenation, for example – and its impact on pelagic, or open-ocean, ecosystem structure for three Paleogene hyperthermals with different magnitudes and durations, Arne Winguth said. The project will focus on a key mechanism involving remineralization of organic matter and oxidation of the dissolved organic matter pool in the ocean, with potentially major implications for future climate evolution.
The researchers aim to answer three key questions. First is how changes in oceanic productivity, organic carbon remineralization, ocean oxygenation, and export efficiency during hyperthermals might have contributed to changes in the oceanic dissolved organic matter reservoir. Second is whether dissolved organic matter release due to enhanced ocean ventilation could have been at least a partial cause of Paleogene hyperthermals. Third are the possible implications of Paleogene climate-carbon cycle changes associated with dissolved organic matter storage and release for future extremes in climate and the environment.
"In particular, the team will evaluate the possibility of extreme changes in response to ecosystem-related fluctuations in dissolved organic matter accumulation and subsequent oxidation and emission from the oceans, because the dissolved organic matter pool is the largest reservoir of easily interchangeable carbon," Arne Winguth said. "This mechanism has not been thoroughly explored as a contributor to a transition into a hothouse climate with more extreme weather patterns."
Asish Basu, chair of UTA's department of earth and environmental sciences, praised the researchers for the originality of the project.
"Uniformitarianism, that the present is the key to the past, a key principle in the natural sciences as opposed to catastrophism, has an interesting twist in Arnie Winguth and his colleagues' approach in this proposed study," Basu said. "By studying past catastrophic climatic change of sudden rise in global temperatures, some 55 million years ago, an outcome of this study may help understand the present and future of global warming phenomena."
Arne Winguth's research focuses on paleoclimate studies, using comprehensive 3-dimensional climate models that consider the general atmospheric and oceanic circulation, and geochemical cycles. His research has been supported by more than $1.5 million in grants from the National Science Foundation and other agencies over the last five years. He earned his Ph.D. in Oceanography at the University of Hamburg and held positions at the University of Chicago, the Max Planck Institute for Meteorology and the University of Wisconsin-Madison before coming to UTA in 2007.
Elizabeth Griffith uses geochemical tracers in the modern environment and on ancient samples to test our understanding of biogeochemical cycling in the ocean with the ultimate goal of better constraining these processes and understanding records of the past. She earned her Ph.D. in geological and environmental sciences at Stanford and held positions at Schlumberger, Stanford University, University of California Santa Cruz and Kent State, before joining UTA in 2013.
Cornelia Winguth's research covers glaciology, paleoclimatology, and marine seismic stratigraphy. She earned her Ph.D. in geology at the University of Hamburg and came to UTA in 2007.
About The University of Texas at Arlington
The University of Texas at Arlington is a Carnegie "highest research activity" institution of more than 52,000 students in campus-based and online degree programs and is the second-largest institution in The University of Texas System. U.S. News & World Report ranks UTA fifth in the nation for undergraduate diversity. The University is a Hispanic-Serving Institution and is ranked as the top four-year college in Texas for veterans on Military Times' 2016 Best for Vets list. Visit http://www.uta.edu to learn more, and find UTA rankings and recognition at http://www.uta.edu/uta/about/rankings.php.