GLOBAL WARMING: Predictions for California

The figures above show the predicted changes in California vegetation as projected by the MAPSS computer model. The simulated future vegetation distribution is for the years 2070 – 2099. (Redrawn with permission from: Confronting Climate Change in California, Union of Concerned Scientists, 1999. The complete report can be accessed at www.ucsusa.org)

What are the projected environmental implications of climate change for the state of California?

Most people would like to know what global warming means for the place they live in, not just for the Earth as a whole. This type of assessment is even more difficult than the attempts at large-scale reconstruction.

A 1999 report by the Union of Concerned Scientists and The Ecological Society of America, titled “Confronting Climate Change in California” provides some clues. The 62-page report addressed a host of problems that might come with global warming, from impacts on agriculture to changes in ecosystems. Some of the key points are:

“Summers will become warmer, but the temperature increase will likely not be as great as the winter increase…. The state’s summers are likely to remain hot and dry, and perhaps become even hotter and drier. Such a consequence, combined with decreased summer stream flow, would exacerbate demands for water in the state.”
“California’s natural ecosystems…are highly sensitive to the availability of water. Thus changes in the timing or amount of precipitation over the next century are likely to have greater impact than changes in temperature.”
“Many of California’s ecosystems are effectively isolated…. Isolation increases the vulnerability of these communities in the face of even modest climate changes….”

Additional expected impacts include changes in California’s agricultural practices, such as “lower profitability of water-intensive crops, including alfalfa, cotton, and grapes” and rising sea level that is “two to three times the increase experienced at San Francisco over the past 150 years.” When snow melts early, in the mountains, it is then not available to provide continuing supply for growing crops in summer. Currently available reservoirs have insufficient capacity to make up the deficit from the missing runoff. When sea level rises, saltwater invades the groundwater below coastal wetlands. Such water is then no longer useful for irrigation.

The changes in Southern California’s marine ecosystem since the mid-1970’s. Increased warming of the waters off Los Angeles have resulted in a 50% decline of cold-water, northern fish species (like the greenspotted rockfish), while warm-water southern fish species (like the Garibaldi) have increased by 50%. (Redrawn with permission from: Confronting Climate Change in California, Union of Concerned Scientists, 1999. The complete report can be accessed at www.ucsusa.org)

The expectations for California, then, largely revolve around the availability of water.

Water is the life-blood of agriculture. Perhaps not surprisingly, agriculture will be the activity most impacted by climate change. This is another reason why highly industrialized nations are likely to be proportionally less affected than less developed nations.

In conclusion, we note that there is enough coal and petroleum in the ground to quadruple and quintuple the amount of carbon dioxide in the atmosphere in the next few hundred years. Such conditions apparently prevailed a hundred million years ago. Dinosaurs ruled the Earth. It was a good time, for reptiles.