Society of Physics Students
Zone 18 Meeting Keynote Talk
Dr. B.D. Santer
Program for Climate Model Diagnosis and Intercomparison
Lawrence Livermore National Laboratory
The Scientific Evidence for a “Discernible Human Influence” on Global Climate
Abstract
Human-caused climate change is not a hypothetical future event. It is real, and we are experiencing it in
our lifetimes. Despite compelling evidence of human effects on global climate, there is a continuing need
for scientists to explain “how we know it’s us”. The first part of my talk will briefly summarize the
scientific underpinning for “discernible human influence” conclusions of the Intergovernmental Panel on
Climate Change and U.S. National Academy of Sciences. The focus will be on so-called “fingerprint”
studies, which seek to identify model-predicted patterns of human-caused climate change in observational
records. The message from such fingerprint research is that observed changes in a number of
independently-measured aspects of the climate system cannot be explained by natural causes alone.
In the second part of my talk, I will briefly discuss projections of the 21st century changes in temperature
and sea-level under different greenhouse gas emissions scenarios, together with the uncertainties in these
projections. What is the likely climatic “shape of things to come”, not only over the 21st century, but for
the next 10 millennia? Are there clever ways of reducing uncertainties in the size and rate of projected
climate changes? Finally, I will provide a personal perspective on some of the “lessons learned” during a
35-year career as a climate scientist.
Note Special time & place (Open to Public)
7:00-8:30 p.m., Friday, March 11th in McLane 121
(more information contact Dr. Douglas Singleton dougs@csufresno.edu or 559-278-2523)