Reconstructing and understanding CO2 variability in the past

Dan Lunt is Professor of Climate Science at the University of Bristol. Dan has over fifteen years’ experience in developing and running climate models in order to address questions and hypotheses related to past and future climate change. A particular focus has been on climate and climate sensitivity in the past. He is leader of the international DeepMIP project (www.deepmip.org), and its predecessor, EoMIP. He was a contributing author to the IPCC AR5, and in 2010 was awarded the Philip Leverhulme Prize for his work on climate modelling. Dan was founding Chief Executive Editor of Geoscientific Model Development, an EGU journal designed primarily for the description and evaluation of models of the Earth System.

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Gavin is a professor of isotope geochemistry at the University of Southampton. His research is primarily concerned with using novel isotopic techniques to gain insights into how and why the Earth’s climate has changed over geological time. Much of his recent research efforts are focused on using boron isotopes in the calcareous shells of foraminifera to reconstruct the state of the oceanic carbonate system in the geological past. In particular he is interested in the mechanisms responsible for the natural CO2 changes that accompanied the waxing and waning of the ice-sheets throughout the Pleistocene, and the role of CO2 in gradual, and sometimes rapid, climate change during the Cenozoic.

Rich Pancost joined the University of Bristol in 2000, became Professor in 2010 and became Director of the Cabot Institute, which engages interdisciplinary approaches to address major environmental challenges, in 2013. He conducts research on how organisms mediate our planet’s chemical environment and how their molecular signatures can be used to constrain climate change parameters. His research has ranged from the controls on arsenic contamination in aquifers to the stability of soil carbon when exposed to warmer temperatures. Three major themes have emerged from his past climate change research: 1) past events broadly confirm climate model forecasts and provide increased confidence in estimates of climate sensitivity; 2) current rates of environmental change are largely without precedent in geological history; and 3) biogeochemical processes respond in complex and unexpected ways to rapid global warming. Collectively, these observations reveal the deep uncertainty in predicting biotic responses to rapid global warming and the sustainability of ecosystems on which we depend.

Professor Maureen E Raymo is a paleoclimatologist and marine geologist who works at the Lamont-Doherty Earth Observatory of Columbia University where she is also Director of the Lamont Deep Sea Sample Repository.  She studies the history and causes of climate change in Earth's past. In 1988 she proposed the uplift‐weathering hypothesis that tied global cooling and the onset of polar glaciations in the late Cenozoic to a drawdown in atmospheric CO2 caused by the uplift of the Himalayas and Tibetan Plateau. In addition to publishing fundamental work on the stratigraphy and chronology of the late Neogene, Raymo has also proposed hypotheses explaining why ice sheets appear to wax and wane primarily at the Earth’s obliquity frequency over much of the Plio-Pleistocene. In 2002, she was awarded the Robert L and Bettie P Cody Award in Ocean Sciences from the Scripps Institution of Oceanography. She is a fellow of both the American Geophysical Union and the American Association for the Advancement of Science. 

Professor Pearson is interested in extracting climatic information from deep sea cores and sediments. He specializes in evolutionary and geochemical studies of planktonic foraminifera, and what they tell us about the long history of climate change on Earth. He has helped develop new proxies for determining past seawater pH and atmospheric carbon dioxide levels, and hence the history of the greenhouse effect. His studies range from the Cretaceous period to Recent.

Prof Pearson has sailed on several occasions with the Ocean Drilling Program. Over the last few years, he has been co-ordinating geological exploration and drilling programmes in coastal Tanzania and Java (Indonesia) where excellently preserved samples have been obtained, providing new insights into the history of tropical climate. "

Gavin is a professor of isotope geochemistry at the University of Southampton. His research is primarily concerned with using novel isotopic techniques to gain insights into how and why the Earth’s climate has changed over geological time. Much of his recent research efforts are focused on using boron isotopes in the calcareous shells of foraminifera to reconstruct the state of the oceanic carbonate system in the geological past. In particular he is interested in the mechanisms responsible for the natural CO2 changes that accompanied the waxing and waning of the ice-sheets throughout the Pleistocene, and the role of CO2 in gradual, and sometimes rapid, climate change during the Cenozoic.

Bärbel Hönisch is an Assistant Professor at the Lamont-Doherty Earth Observatory of Columbia University in New York. She obtained a Diploma in Biology from the University of Bremen, and a PhD in Natural Sciences, studying at the Alfred-Wegener Institute of Polar and Marine Research in Bremerhaven, Germany.

Her research is focused on understanding the role of the ocean, and in particular the role of marine carbonate chemistry in global climate change. As she was originally trained as a (marine) biologist, her way of approaching paleoceanographic questions often includes a biological component. Culture experiments with living marine calcifiers are an important tool of her research to validate paleoceanographic proxies in foraminifers and corals, in particular the boron isotope proxy for seawater pH. She applies those findings to the reconstruction of seawater carbonate chemistry and atmospheric CO₂ variations through Earth history. Current projects include the reconstruction of ocean acidification at the Paleocene/Eocene Thermal Maximum, estimating the secular variation of boron isotopes in seawater and the validation of the B/Ca proxy in planktic foraminifers. 

Philip Sexton is a palaeoceanographer and micropalaeontologist who works as an Associate Professor at The Open University. He received his PhD from the National Oceanography Centre, Southampton, following which he was a European Commission Outgoing International Research Fellow at Scripps Institution of Oceanography and then a Leverhulme Trust Research Fellow at Cardiff University. His research spans the disparate fields of the palaeoceanography of the very warm Palaeogene and the cold Pleistocene, but with a unifying emphasis on understanding links between the biosphere, carbon cycling and climatic variability in both end-member climate states. Recent research has focussed on exposing the dynamics of carbon cycling across rapid climatic warming events within the Eocene extreme ‘greenhouse’, where he has offered an alternative explanation for their genesis compared to prevailing views that invoked repeated releases of carbon from buried sedimentary reservoirs. He is also Academic Advisor for a new BBC 7-part TV series exploring the natural history of our oceans (‘Blue Planet 2’) to be televised in 2018.

Aradhna Tripati is an assistant professor at UCLA in the Department of Atmospheric & Oceanic Sciences and Earth & Space Sciences, and a Visiting Fellow at the California Institute of Technology. Her research is focused on the development and application of novel tools for studying climate change. She graduated with a PhD from the University of California, Santa Cruz in 2002. For the next eight years she was a Research Fellow at the University of Cambridge, UK, where she studied past warm periods in Earth’s history including the history of ice sheets in both the Northern and Southern Hemispheres and the history of atmospheric carbon dioxide levels. 

Dr Michael Ellis joined the BGS in 2008 as Head of the Climate Change programme. Dr Ellis oversees the development of a broad range of climate-change research, including palaeoclimate and palaeoenvironmental analyses of past episodes of rapid climate change. Research includes analyses of CO₂ proxies via alkenones (in coccolithophorids), B/Ca ratios (in benthic forams), biome and biotope reconstruction, palaeoclimate GCM modelling, as well cognate investigations of soil-carbon dynamics and flux. Ellis was the founder and current Chair of the American Geophysical Union’s Earth and Planetary Surface Processes Focus Group, and he has served as an associate editor of Journal of Geophysical Research, Surface Earth, JGR Solid Earth, Basin Research, Geology,Biogeosciences, and he is  currently on the Editorial Advisory Board of EOS.  

James (Jim) C Zachos is a Professor of Earth and Planetary Sciences at the University of California at Santa Cruz (UCSC).  He received his PhD in Oceanography from the University of Rhode Island in 1988, was a post-doctoral fellow at the University of Michigan, and a fellow at the University of Cambridge.  Zachos’s research primarily focuses on the dynamics of climate and ocean carbon cycle coupling over geologic time, particularly during periods of rapid and extreme change.  He has authored/co-authored 115 peer-reviewed publications on topics ranging from Eocene global warming and ocean acidification to Oligocene ice-sheet evolution, and was a contributor to the 2007 IPCC report. He is a fellow of the American Geophysical Union, the Geological Society of America, the Canadian Institute for Advanced Research, and the California Academy of Sciences, and is a recipient of the National Young Investigator, AGU Emiliani, and Humboldt Awards.  He is also a member elect (2011) of the American Academy of Arts and Sciences. 

Professor Maureen E Raymo is a paleoclimatologist and marine geologist who works at the Lamont-Doherty Earth Observatory of Columbia University where she is also Director of the Lamont Deep Sea Sample Repository.  She studies the history and causes of climate change in Earth's past. In 1988 she proposed the uplift‐weathering hypothesis that tied global cooling and the onset of polar glaciations in the late Cenozoic to a drawdown in atmospheric CO2 caused by the uplift of the Himalayas and Tibetan Plateau. In addition to publishing fundamental work on the stratigraphy and chronology of the late Neogene, Raymo has also proposed hypotheses explaining why ice sheets appear to wax and wane primarily at the Earth’s obliquity frequency over much of the Plio-Pleistocene. In 2002, she was awarded the Robert L and Bettie P Cody Award in Ocean Sciences from the Scripps Institution of Oceanography. She is a fellow of both the American Geophysical Union and the American Association for the Advancement of Science. 

BSc (Hons) Geography, University of St Andrews, 2000; PhD “Surface ocean circulation and organic carbon export across the mid-Pleistocene climate transition”, University of Durham, 2004.  Dr McClymont’s research focuses on the application and development of organic geochemistry (biomarker) proxies to a range of sedimentary archives, including marine sediments and peatlands. She is interested in applying these proxies to understand how key ocean/atmosphere connections have developed during the late Cenozoic, and to consider the biogeochemical feedbacks which may also have been important. She has tested the viability of the alkenone-based proxy for sea-surface temperatures (UK37’) in the face of extinction and evolution events in their source organisms (the Haptophyte algae). She has used novel alkenone distributions to reconstruct subpolar water mass distributions over the last 3 million years, exploited the differences between the UK37’ and TEX86 proxies to understand changes in upwelling intensity on centennial timescales, and identified evidence for changing greenhouse gas production from European peatlands over the last 3000 years. In seeking to understand the role played by atmospheric CO2 concentrations in some of the climate changes she has reconstructed, Dr McClymont has also been working with stable carbon isotope measurements of the alkenone biomarkers in order to develop a record of pCO2 which can be used to consider the controls and impacts of CO2 variability in the past.

Helen Coxall graduated with a BSc in Geology/Biology from Manchester University before completing a PhD at Bristol on the evolution of Eocene planktonic foraminifera and climate. She held Research Fellowships at the National Oceanographic Centre, UK (Royal Commission for the Exhibition of 1851) and the University of Rhode Island, before joining Cardiff University as a Royal Society University Research Fellow in 2005. She returned to Cardiff in 2010 after 18 months as a visiting lecturer at Stockholm University.

Helen is interested in ocean and climate systems of the early Cenozoic, when atmospheric CO₂ is thought to have been 2-3 X preindustrial levels. She has a particular interest in pelagic ecosystems and the ‘service’ role they play in responding to or modulating climate through the carbon system. Her research involves generating marine geochemical climate proxy records (typically CaCO₃ and CaCO₃–based oxygen and carbon stable isotopes) using benthic and planktonic foraminifera to reconstruct changes in water column physical, chemical and biological properties. Her expertise in planktonic foraminifera taxonomy, isotopic palaeoecology, evolution and taphonomy provides optimal constraints on proxies of ocean thermal and nutrient stratification, which are critical for obtaining realistic estimates of surface ocean/atmospheric CO₂. 

Appy Sluijs (1980) is an Assistant Professor at Biomarine Sciences, Institute of Environmental Biology, Utrecht University, The Netherlands. Sluijs studied biology and biogeology in Utrecht and at the University of California at Santa Cruz, USA. Sluijs is a member of The Young Academy of the Royal Netherlands Academy of Arts and Sciences. He was awarded the Outstanding Young Scientists Award of the European Geosciences Union (EGU) in 2007. In 2010, he received the prestigious Vening Meinesz Prize for young geoscientists and the Heineken Young Scientists Award for Environmental Sciences. He is an editor of the open access journal Climate of the Past, published by the European Geosciences Union.

His research focuses on reconstructing temperature, hydrology, biogeochemical cycles and sea level during episodes in Earth’s history that were characterized by rapidly increasing, or generally high concentrations of CO₂ in the atmosphere. He combines micropaleontological and geochemical techniques to understand system Earth under ‘greenhouse’ conditions. Funded through an ERC Starting Grant, he has recently started to quantify the physiological and biogeochemical response of dinoflagellates to changing seawater CO₂ concentrations and pH. This response may be developed into a proxy to reconstruct ocean acidification in the geological past. 

Michael White grew up in the Washington DC area and in Santa Fe, NM. He received his undergraduate degree in Environmental Science in 1992 from the University of Virginia, where he conducted research on leaf physiology and morphology with Hank Shugart. He studied remote sensing, carbon cycle modeling, and vegetation phenology with Steven Running at the University of Montana and obtained his MS in 1996 and Phd in 1999. Until 2008, Michael held a faculty position at Utah State University. He then accepted the position of climate science editor for Nature and moved to London for two years. In 2010, he transferred to Nature’s San Francisco office, where he now holds the position of Senior Editor. 

Rich Pancost joined the University of Bristol in 2000, became Professor in 2010 and became Director of the Cabot Institute, which engages interdisciplinary approaches to address major environmental challenges, in 2013. He conducts research on how organisms mediate our planet’s chemical environment and how their molecular signatures can be used to constrain climate change parameters. His research has ranged from the controls on arsenic contamination in aquifers to the stability of soil carbon when exposed to warmer temperatures. Three major themes have emerged from his past climate change research: 1) past events broadly confirm climate model forecasts and provide increased confidence in estimates of climate sensitivity; 2) current rates of environmental change are largely without precedent in geological history; and 3) biogeochemical processes respond in complex and unexpected ways to rapid global warming. Collectively, these observations reveal the deep uncertainty in predicting biotic responses to rapid global warming and the sustainability of ecosystems on which we depend.

Dan Breecker received a BA from Amherst College in Geology in 2001, where he completed a senior thesis on quartz-mica schists from Syros Greece as part of a Keck Consortium project. After college he worked for the USGS for one summer as part of the USGS/NAGT summer intern program. Dan began graduate school at the University of New Mexico in 2002 where he worked on calibrating an oxygen isotope geothermometer for his M.S. research and studied stable isotope ratios of CO2, water and calcite in desert soils for his PhD research. He graduated from UNM in 2008 after which he did one year of an NSF postdoctoral fellowship at the University of Arizona before starting his current position at the University of Texas at Austin.  

Dana Royer is an Associate Professor at Wesleyan University in the Department of Earth and Environmental Sciences. He explores how plants can be used to reconstruct ancient environments, and the paleo-physiological underpinnings behind these plant-environment relationships. Current areas of interest include the reconstruction of atmospheric carbon dioxide levels from the stomatal distributions in plant leaves, and the development of mechanistically-grounded proxies for climate and leaf ecology from the size and shape of fossil leaves. He also compiles Phanerozoic carbon dioxide records and investigates the strength of carbon dioxide-temperature coupling over multi-million-year timescales. In 2010, Dana was awarded the Donath Young Scientist Award from the Geological Society of America. 

Roderik van de Wal, Utrecht University, The Netherlands is a climatologist interested in ice in the climate system in the broadest context. He has been working on the contribution of small glaciers to sea level, changes of the Greenland ice sheet, by means of mass balance observations and ice sheet modelling. More recently the ice sheet modelling has been extended to all ice sheets on Earth over long time scales addressing ways to integrate key paleoclimate proxies as benthic d18O records and information from ice cores in a consistent framework with ice sheet models as tool to unravel the temperature and ice volume changes of d18O records. Lately this work resulted in the reconstruction of CO2 over the last 20 Myrs. 

Dan Lunt is Professor of Climate Science at the University of Bristol. Dan has over fifteen years’ experience in developing and running climate models in order to address questions and hypotheses related to past and future climate change. A particular focus has been on climate and climate sensitivity in the past. He is leader of the international DeepMIP project (www.deepmip.org), and its predecessor, EoMIP. He was a contributing author to the IPCC AR5, and in 2010 was awarded the Philip Leverhulme Prize for his work on climate modelling. Dan was founding Chief Executive Editor of Geoscientific Model Development, an EGU journal designed primarily for the description and evaluation of models of the Earth System.

Rob DeConto is a Professor of Geosciences at the University of Massachusetts-Amherst. He maintains adjunct research positions at Columbia University and Victoria University of Wellington. Rob’s background spans geology, oceanography, and atmospheric science, and he has held research positions at both the US National Center for Atmospheric Research (NCAR) and the National Oceanic and Atmospheric Administration (NOAA). His early research used numerical climate models to better understand the mechanisms responsible for past periods of extreme global warmth. In recent years, his research has shifted toward the polar regions- including fieldwork in Antarctica, the development of coupled climate-ice sheet models, and the application of those models to a wide range of past and future climate scenarios. Rob currently serves on a number of national and international science boards and advisory panels and he is currently co-chair of ACE (Antarctic Climate Evolution), an international research program under the auspices of the Scientific Committee on Antarctic Research.  

Professor Huber's group (the Climate Dynamics Prediction Lab) works on developing a better understanding of and ability to predict the dynamics of the climate system with an emphasis on investigating past warm climates as a window into future behavior.  Much of this work focuses on atmosphere-ocean dynamics with an emphasis on hot conditions, e.g. the tropics. Always in Professor Huber's mind is the implications of changing climates for life and humanity. At present, much of his focus is on reconstructing the dynamic range of past tropical climates and inferring thermal limits of terrestrial and marine organisms.

How sensitive is our climate system to the emission of greenhouse gases such as carbon dioxide and methane? What are the biogeochemical consequences of adding carbonic acid (CO2 dissolved in rainwater) to the ocean? How sensitive are organisms and ecosystems to all these changes? Because of the complexity of the Earth’s climate system, and often, simply because of our lack of imagination about all the different ways in which the Earth can respond to being poked, a comprehensive answer to these questions is extremely difficult to achieve, even with our best climate and carbon cycle models. Understanding the past can help, as Earth history is characterised by an extraordinary richness of climatic and carbon cycling behaviour. Andy Ridgewell's work surrounds creating computer model representations of the key Earth system components and applying them in interrogating the past so as to help better constrain the future.