In December, January, and March, California experienced severe flooding, rain, snow, and wind due to atmospheric rivers, areas of high moisture that transport water vapor from tropical regions to different locations across the world. Once atmospheric rivers arrive on land, they release water in the form of precipitation. These rivers can range anywhere from 250 to 375 miles in width and 1,000 to 2,000 miles in length. Unlike those in California, not all atmospheric rivers are catastrophic and dangerous. Rather, they are essential for delivering water to areas that need it. However, due to climate change, these phenomena could become significantly stronger and more frequent.
Last December, over one third of Americans were issued winter weather and wind chill alerts in response to reports of unprecedented weather conditions anticipated in 37 states around the country. California was one of these states. By the end of December 2022, about 17 feet of snow had fallen in Sierra Nevada, and since October 2022, 50 feet of snow have fallen in this area. In terms of rainfall, some areas in California were seeing over 40 inches of rain from Dec. 26 to Jan. 11. Millions of people were under flood alerts and thousands were told to evacuate.
Another atmospheric river has already begun to hit California, the eleventh this winter. On March 10, Governor Newsom and later President Biden issued a state of emergency for 34 counties in the state. As of Monday, 18 million Californians were under flood alerts, and this number continues to grow. Elevations over 7,000 feet are expected to see four feet of snow and those over 9,000 are projecting snowfall amounts around eight feet. Lower elevations are expected to experience significant flooding and high winds.
Climate change exacerbates natural disasters and extreme weather events. Catastrophes including hurricanes, floods, and wildfires are only a few examples of disasters anticipated to increase in severity and frequency, with atmospheric rivers expected to see similar trends. When our planet increases in temperature, the atmosphere is able to hold more water vapor. This means rainfall numbers and storm intensity will become even greater. According to NASA, these atmospheric rivers will become larger and more frequent. They estimate that they will increase in size by 25 percent and increase in frequency by 50 percent.
As we continue to accelerate climate change, we will only see more natural disasters and endanger countless more people. As we emit more carbon dioxide due to our reliance on fossil fuels, our atmosphere will absorb more heat. With this added heat, more water vapor can be held in the air meaning more severe and intense rainfall. To prevent these storms, we need to start transitioning from fossil fuels to clean energy and prioritize achieving net-zero emissions.