Select modem speed to see Video
VivoActive player required
(Professor at Stanford University, MacArthur Fellowship, the American Association for the Advancement of Science Westinghouse Award for Public Understanding of Science and Technology)|
After receiving his Ph.D. in Mechanical Engineering and Plasma Physics from Columbia University in 1971, Stephen Schneider focused on the influence of greenhouse gases and suspended particles on the earth's climate as a postdoctoral researcher at NASA's Goddard Institute for Space Studies, and later at the National Center for Atmospheric Research, where he remained until 1996. In 1992, Dr. Schneider was awarded a MacArthur Fellowship for his ability to integrate and interpret the results of global climate research through public lectures, seminars, media appearances, and research. He was also honored with the American Association for the Advancement of Science Westinghouse Award for Public Understanding of Science and Technology for his ability to express environmental science and its implication for public policy to the general public. Currently he is a Professor in the Department of Biological Sciences and a Senior Fellow at the Institute for International Studies at Stanford University.
Thank you very much, Mr. Vice President, Mr. President. What we're addressing at the moment is, "so what if the climate changes?" This is a question that scientists have spent a long time on, doing literally hundreds of studies, suggesting outcomes ranging from catastrophic to mild. Let's take a look at just two examples –– the sea level question and the question of hydrologic extremes, droughts and floods. We all remember the terrible pictures from hurricane Andrew, which resulted in losses on the order
of $40 billion in Florida and other areas around the Caribbean. Could we have had something to do with that? If you increase the temperature of the oceans, it increases evaporation, it might make storms stronger. That's very controversial. But one thing
we know that isn't controversial is that before 1987 there were no losses larger than $1 billion. And now the insurance industries are very concerned that there have been several in the tens of billions.
What else do we know that's not controversial? Sea levels have gone up and are projected, typically, to go up six inches to maybe three feet, depending upon how things turn out in the next century. And whether storms are augmented in strength by global warming or remain at their natural levels, they'll be causing flooding from a higher sea-level base. As a result of that, the damages would go further inland.
What about the hydrologic extremes? Well, we all saw pictures of the 1988 drought. We know about the seemingly endless stories of floods now. And the question is, "Has nature rolled us a double snake eyes, or have we started to load the dice?" Again, physics says if you increase the heating of something that has water in it, more water will evaporate. So, what that suggests is that more water in the air means that when it does rain, the rainfall can be more intense. When it's dry, you can have more evaporation.
The question is, what's happening? A line that we often use in science is, well, in God we trust, but for the rest of us, please show data. Dr. Tom Karl and his colleagues in North Carolina, for example, have concluded that there has been about a 10 percent increase in precipitation across the United States since 1910. The interesting part, as Tom says, is, "The increase in precipitation is reflected primarily in the heavy and extreme daily events." Translated: Gully washers. The bulk of the rainfall increase has been in those kinds of damaging, extreme events. A pattern is emerging, and the pattern is consistent with the expectations from our models. So, while no one event certainly could be laid to the doorstep of global warming, the increasing frequency and magnitude of severe storms could very well be the first signs of the canary in the cage starting to quiver. The IPCC concluded with a paragraph I know well as a lead IPCC author, and I'll quote what it said in its last paragraph of the summary for policy makers. "When rapidly forced, nonlinear systems are especially subject to unexpected behavior." In my words, that means reducing the pressures humans put on nature is insurance against potential nasty surprises.