Ars Live #10, filmed by Chris Schodt and produced by Jennifer Hahn. (video link)
UC-Berkeley environmental scientist Lynn Ingram joined us for the one-year anniversary episode of Ars Technica Live, and she gave us a broad historical perspective on climate change. Ingram's special focus is paleoclimatology, or the study of Earth's ancient ecosystems. She explained that she spends a lot of time in the lab dissolving rocks, bones, and shells in acid to get good carbon dates on them. Working with other researchers, she has found that California's climate has always been subject to dramatic fluctuations, but now those are being exacerbated by human activity.
California history has always been one of drought and flood. Ingram told us about the southwestern region's great medieval warming period roughly 800 years ago, which may have caused drought for over a century. People living in the region abandoned their settlements and moved away, while plant life struggled to hold on. In the more recent past, California's central valley became an inland sea after 40 days of rain in 1862. This is the sort of megaflood that is due to happen again, Ingram told us, because they seem to occur roughly every two centuries. Even without humans contributing to rapid climate change, we should be preparing for another flood of this magnitude—but now, with atmospheric rivers becoming more common, they will probably happen more often.