In journal Science Advances, a pair of scientists from the National Center for Atmospheric Research and the University of California, Los Angeles, published their analysis on the impact of global climate change and atmospheric river creations from warming can impact people in California.

While California has had megafloods in the past, including one leaving Sacramento, in 1861, under ten feet of water and 4,000 people dead, a flood similar to that would be severely more devastating today given the complex nature of society and that at the time, only 500,000 people were living in California. Today there is about 39 million people.

How do these megafloods occur? They occur when atmospheric conditions over the Pacific Ocean create long narrow streams of highly moisturized air called atmospheric rivers. When such rivers reach the mountains in California, where the moisture normally gets released as snow, but due to warmer climate, it comes down as torrential rain instead. These rain days can last weeks saturating the valleys with water.

While these can occur once every thirty to fifty years, the authors’ analysis based on climate change and weather models, show that current warming trends in California has already double the risk of these megaflooding events in the winter with the risk predicting to rise as global temperature rises as well.

While climate change is a contested debate, the reality is when you as yourself which side we want to err on, it’s safe to address the causes of climate change now rather than finding out that we were wrong in denying it as the cost will be much higher then.

X Huang and DL Swain. Climate change is increasing the risk of a California megaflood. Science Advances (2022).  DOI: 10.1126/sciadv.abq0995