Presenter Information

Kate Marvel, Columbia University

Start Date

1-3-2021 3:45 PM

End Date

1-3-2021 3:00 PM

Access Type

Open Access

Abstract

Despite improvements in computing power, climate modeling, and basic theoretical understanding, the Earth’s physical response to a doubling of atmospheric carbon dioxide remains uncertain. Can observations be useful in constraining this theoretical quantity? We have high-­‐quality information on recent trends: greenhouse gas concentrations have increased since the industrial revolution, and the planet has warmed in response. But I will argue that this recent history provides only weak constraints on the eventual climate sensitivity: observations of a transient climate are poor predictors of a future equilibrium state. Reconstructions of past equilibria both colder (the Last Glacial Maximum) and warmer (the mid-­‐Pliocene) than the present provide stronger constraints, suggesting that the extremely high climate sensitivities of some state‐of‐the‐art climate models are unrealistic. I’ll present a framework for facilitating apples-to-apples comparisons of past and future climate and discuss how to understand, reduce, and communicate the uncertainties associated with future climate response.

Biography

Dr. Marvel uses climate models, observations, paleoclimate reconstructions, and basic theory to study climate change. Her work has identified human influences on present-­‐day cloud cover, rainfall patterns, and drought risk. She is also interested in future climate changes, particularly climate feedback processes and the planet's sensitivity to increased carbon dioxide. Dr. Marvel teaches in Columbia's MA in Climate & Society Program and writes the "Hot Planet" column for Scientific American. Named one of "15 Women Who Will Save the World" by Time Magazine, she has been profiled by the New York Times and Rolling Stone, and her 2017 TED talk has been viewed over one million times. Before becoming a climate scientist, she received a PhD in theoretical particle physics from Cambridge University, where she was a Gates scholar.

ORCID

0000-0002-9771-6720

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Mar 1st, 3:45 PM Mar 1st, 3:00 PM

What can history tell us about the future? Using recent observations and paleoclimate proxies to constrain equilibrium climate sensitivity

Despite improvements in computing power, climate modeling, and basic theoretical understanding, the Earth’s physical response to a doubling of atmospheric carbon dioxide remains uncertain. Can observations be useful in constraining this theoretical quantity? We have high-­‐quality information on recent trends: greenhouse gas concentrations have increased since the industrial revolution, and the planet has warmed in response. But I will argue that this recent history provides only weak constraints on the eventual climate sensitivity: observations of a transient climate are poor predictors of a future equilibrium state. Reconstructions of past equilibria both colder (the Last Glacial Maximum) and warmer (the mid-­‐Pliocene) than the present provide stronger constraints, suggesting that the extremely high climate sensitivities of some state‐of‐the‐art climate models are unrealistic. I’ll present a framework for facilitating apples-to-apples comparisons of past and future climate and discuss how to understand, reduce, and communicate the uncertainties associated with future climate response.