A wide-ranging assessment of climate change in the Southwest

May 3rd, 2013 | by Ian James | Comments

A newly published scientific assessment of climate change in the Southwest brings together the work of 120 contributors in a single book that examines emerging climate trends, future projections and effects on water supplies, communities, agriculture, ecosystems and more. The report’s executive editor, Gregg Garfin, said the 506-page volume showcases the “most comprehensive state of knowledge about regional climate change.”

The book is one in a series of technical input reports for the National Climate Assessment, and this week Garfin and other researchers led a teleconference to discuss the report’s overarching conclusions. Garfin, who is Deputy Director for Science Translation and Outreach at the University of Arizona’s Institute of the Environment, summarized some of the changes now being observed by researchers, as well as other changes projected in the future:

“The Southwest is getting hotter. In the last 10 years, we’ve experienced fewer cold waves and more heat waves than any other 10-year period in the last 110. And for the future, higher temperatures are predicted with longer and hotter heat waves. So, picture San Francisco with temperatures more like San Diego or Sacramento with temperatures higher than Riverside, California. And also picture the ramifications of those higher temperatures for more wildfires, leading to power grid failures, and decimation of conifer forests from a combination of drought and insect outbreaks. Snow, which is the key to our water supplies, is melting earlier. That’s resulting in earlier stream flow and it’s decreasing water supply reliability and having that … shorter snow season basically is fueling more wildfires. So, what’s projected for the future is even less snowpack, less flow in our large lifeblood rivers and more protracted droughts, and this will lead inevitably to water tradeoffs between agriculture, cities and the environment. Another thing that California scientists have been instrumental in learning about is ‘atmospheric rivers’ like the Pineapple Express. These are narrow bands of water vapor a mile high in the sky and they deliver the same flow of moisture as 15 Mississippi Rivers, and these have caused the largest floods in California history, and they can penetrate as far inland as Utah or New Mexico, and these kinds of storms are projected to become more frequent and wetter in the future. We’ve also already witnessed eight inches of sea level rise along the California coast, and that doesn’t include the effects of high tides and storm surges. And what’s projected for the future is as much as seven times as much sea level rise during the next 90 years. And let me just touch very briefly on public health. I think it’s pretty easy to picture extreme urban heat in the interior of the Southwest. This is also a risk for coastal cities, as is the spread of mosquito-borne diseases, and disadvantaged populations such as the elderly and people with limited access to medical care will bear the brunt of those kinds of projected impacts.”

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