As Californians know, we are living through a series of mega rainstorms know as “atmospheric rivers.”

These are super powerful storms, akin to rivers in the sky, that dump massive amounts of rain causing flooding, mudslides, power outages and loss of life and property damage.

January’s deluge, aka the “Pineapple Express,” originated in Hawai‘i where warm air rose to create low air pressure at the Earth’s surface, producing warm water vapor plumes that, as they moved east across the Pacific Ocean, arrived in California as atmospheric rivers.

History has seen these rivers drench California before. What we have not seen are the severity of these kind of storms exacerbated by climate change.

One of the most well understood aspects of global warming is its effect on rain. In a warmer atmosphere, evaporation rates increase, transforming more water molecules into vapor.

In other words, a warming atmosphere holding more water means more severe storms.

Given that we are certain to go beyond the predicted 1.5 C (2.7F) increase in global temperature well before midcentury, we should expect more frequent and sever atmospheric river downpours.

For all their destruction, the storms are filling up reservoirs and adding to the Sierra snowpack, both major sources of California water.

For example Lake Shasta, the state’s largest reservoirm has increased from 31% capacity in December to 42% as of Jan. 11. Locally, Lake Cachuma is on the brink of filling and spilling for the first time in more than a decade.

The Sierra snowpack accounts for 30% of California’s water supplies. As of Jan. 11, the snowpack measured 153.7 inches, three times the average amount for this time of year.

However, there are three things that we, and our water managers, must consider: despite the rain California’s chronic drought is not over, a warm spring will prematurely melt the snowpack and cause it to run off rather than be captured for water usage, and we must ensure our infrastructure is fortified to the extent it can capture the water from these kinds of “new normal” storms. 

71% of California was experiencing “severe” drought as 2023 began. That number dropped to 46% after the first set of January storms.

But the current storms can’t resolve the driest period in 1,200 years in the American West, including California. For example, groundwater basins, where thousands of wells have run dry, will take years to recharge.

Snowpack research has shown that the closer to the ocean the snowpack is, it is more vulnerable to early runoffs, including the Sierra snowpack. Higher temperatures this spring will cause a faster melt, making it more difficult to capture and store the water for the hot summer months.

One of the few things California legislators, on both sides of the aisle, have agreed upon is that the state needs to update its water systems and  increase our ability to capture and store water.

Assembly Bill 62 would increase above and below groundwater storage by some 3.7 million acre-feet by 2030. Given the reality that climate change has not only increased heat and drought, but now includes these intense rainstorms, this should be clear for both the Legislature and Gov. Gavin Newsom.