Events & Media

The Bren School of Environmental Science & Management
at the University of California, Santa Barbara



"Can Global Warming Be Held to 2° C above Pre-Industrial?"

David Lea
Professor, Earth Science
UC Santa Barbara

Wednesday, April 18, 2012
11:30 - 12:30
Bren Hall 1414

"David Lea's background combining geochemistry of the oceans and a policy perspective gained by his recent sabbatical at the US State Department in Washington, DC., will lead to an especially insightful presentation on global warming." — John Melack


This talk will examine two related questions:

1. How feasible is it to limit global warming to 1.5 or 2 degrees Centigrade?
2. To what extent is it possible to establish a particular warming level as dangerous?

The first question can be readily addressed, because the main factors and uncertainties that determine future warming are either well characterized or can be specified: i.e., future emission pathways of GHGs and aerosols, climate sensitivity (i.e., strength of climate feedbacks) and the current cooling effect of aerosols, and earth system responses, such as carbon-cycle feedbacks. A critical economic constraint on the feasibility of limiting warming is the maximum possible rate of absolute emission reduction, which is limited by how rapidly energy infrastructure can be turned over.

The second question regarding what is dangerous is more challenging because it involves vast uncertainties in climate projections, the behavior of so-called “tipping elements” in the climate system, the ability to adapt to climate change, and subjective judgments about the importance of climate impacts and, especially, climate extremes. One compelling argument for limiting warming to a specific level centers on the identification of threshold temperatures for specific tipping elements in the climate system that, if tipped, would have large societal impacts. But identifying such thresholds is no simple matter.

David Lea is Professor of Earth Science and a member of the Marine Science Institute at the UCSB, where he has been a faculty member since 1989. He received his PhD in oceanography from the .Massachusetts Institute of Technology – Woods Hole Oceanographic Institute Joint Program in 1990. His research interests include climate change, global warming, climate evolution during the ice ages, marine geochemistry, and the carbon cycle. He has published 90 scholarly papers on these topics, including 16 in Science and Nature. Professor Lea has been a visiting professor at the University of Chicago and Cambridge University. His awards include the UCSB Academic Senate Distinguished Teaching Award (2001), a John Simon Guggenheim Fellowship (2002-03), a Leverhulme Visiting Professorship, a Clare Hall Visiting Fellowship (both 2002-03, Cambridge, UK), the American Geophysical Union Emiliani Lectureship (2007), a Leopold Leadership Fellowship (2009), a Jefferson Science Fellowship (2010) and a Google Science Communication Fellowship (2011). He developed and chaired UCSB’s 2007 Global Warming-Science and Society Event Series, and in 2010-2011 served as science advisor to Todd Stern, President Obama’s Special Envoy on Climate Change.

NOTE: Community colloquia are generally talks of broad interest geared toward a diverse, sophisticated audience. Their purpose is not only to enhance knowledge and understanding, but also to bring people together and promote interaction that will strengthen the community.


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