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DOE Pulse
  • Number 455  |
  • December 28, 2015

California, here they come: Weather patterns, warming could produce extremes

La Nina (left) cools off the ocean surface (greens and blues) in the winter of 1988. On the right, El Nino warms it up (oranges and reds) in the winter of 1997.

La Nina (left) cools off the ocean surface
(greens and blues) in the winter of 1988.
On the right, El Nino warms it up
(oranges and reds) in the winter of 1997.

The weather patterns El Nino and La Nina may bring some ornery conditions to California later this century.

A research team from DOE's  Pacific Northwest National Laboratory and Utah State University, funded by DOE ’s Office of Science, studied the patterns to gain a better sense of California’s future weather as the earth warms up. The scientists concluded that El Nino and La Nina, which alternately warm and cool the Pacific Ocean, could lead to at least a doubling of extreme droughts and floods in the state.

In the project, the research team looked at what happens to California in global climate models. To examine the most extreme case, the scientists simulated 2006 to 2080 using conditions in which very few efforts are made to reduce greenhouse gas emissions.

The results showed that as the emissions continue to increase, California seasons will exhibit more excessively wet and excessively dry events, with the frequency of droughts doubling and floods tripling between the early 20th century and late 21st century.

"By 2100, we see more—and more extreme—events. Flooding and droughts will be more severe than they are currently," predicts PNNL atmospheric scientist Jin-Ho Yoon.

But why? The increase in California precipitation won't be enough to account for the wild weather. So Yoon and colleagues removed the cycling of El Nino and La Nina from the model by programming steady warming.

Without the cycles of warm and cool, the frequency of extreme events did not rise, indicating the weather patterns will play a role in the century's extreme weather. With rough weather on the way, a better understanding of El Nino and La Nina might help California predict and prepare for the wet and dry.  

The scientists’ findings were published October 21, 2015, in Nature Communications.  

More: http://www.pnnl.gov/news/release.aspx?id=4228

Submitted by DOE’s Pacific Northwest National Laboratory