On the left, La Nina cools off the ocean surface (greens and blues) in the winter of 1988. On the right, El Nino warms up it up (oranges and reds) in the winter of 1997. Credit: Jin-Ho Yoon/PNNL
El Nino and global warming work together to bring more extreme weather
October 21, 2015 DOE/Pacific Northwest National Laboratory
In the future, the Pacific Ocean’s temperature cycles could disrupt more than just December fishing. A study published in Nature Communications suggests that the weather patterns known as El Nino and La Nina could lead to at least a doubling of extreme droughts and floods in California later this century. The study shows more frequent extreme events are likely to occur. Other research shows the Golden State’s average precipitation increasing gradually, but not enough to account for the occurrence of extreme events. A better understanding of what gives rise to El Nino and La Nina cycles — together known as El Nino-Southern Oscillation — might help California predict and prepare for more frequent droughts and floods in the coming century. “Wet and dry years in California are linked to El Nino and La Nina. That relationship is getting stronger,” said atmospheric scientist Jin-Ho Yoon of the Department of Energy’s Pacific Northwest National Laboratory. “Our study shows that ENSO will be exhibiting increasing control over California weather.”
California is experiencing one of the most severe droughts in its history, but it’s not clear if a warmer world will make droughts worse, more frequent or perhaps even improve the situation. After all, warmer air can hold more water, and some research suggests global warming could increase California’s average rain and snowfall. However, research also suggests future rain will come down more as light drizzles and heavy deluges and less as moderate rainfall. Yoon and colleagues from PNNL and Utah State University in Logan, Utah, wondered if droughts might follow a similar pattern.