Last month, California was slammed with severe storms and torrential rains, causing flooding, mudslides, power outages and deaths. It was record-breaking; San Francisco experienced its wettest 10-day period since 1871. At one point, 90% of California’s population was under a flood watch. Yet, despite the remarkable precipitation, California is still in drought. Why?

The reason boils down to how the state collects and stores water. Due to limited storage space and an inability to fully capture and treat the water, most of the rain that fell flowed into the Pacific Ocean, rendering it unusable.

However, if California does not design and build storm water systems capable of capturing, storing and treating more of the rainfall, the state will be in dire trouble. The intensity of extreme weather and climate events will only worsen with time as humans continue fueling climate change. 

Last month’s storms, for example, were record-breaking due to the effects of climate change. Their root cause was atmospheric rivers. Atmospheric rivers are streams of moisture from the tropics that form through the evaporation of warm ocean water. They typically deliver much of the state’s annual precipitation. As global temperatures rise due to climate change, the air is warmer and carries more moisture—resulting in the atmospheric rivers unleashing more precipitation. This year’s atmospheric rivers were further coupled with a bomb cyclone, which only increased their intensity.

Atmospheric rivers are not the only weather event strengthened by climate change. California—which usually oscillates between wet and dry periods—has dealt with drought numerous times in the past. However, the state has been in severe drought for nearly three years. The American West itself is in its driest 22-year period in over 1,200 years. The severity of the drought can be attributed to climate change; global warming increases evaporation on land, reducing surface water and drying out vegetation.

Droughts result in water shortages—California’s current crisis. Most state reservoirs are below their historical average capacity, with Lake Mead and Powell, the country’s largest reservoirs, badly depleted. To deal with the lack of water, the state has enacted a few water conservation regulations on water suppliers and citizens while laying out future infrastructure goals. They have done little else. Hence, even after such extreme precipitation, California continues to be in severe drought.  

With greenhouse gas emissions not stopping anytime soon, California must act now before the water shortage worsens. But how?

Firstly, California needs a greater storage capacity. Currently, water is contained in the snowpack, reservoirs and groundwater aquifers. However, when rain falls quickly in such large amounts, the snowpack is not formed at lower elevations, reservoirs are filled up too swiftly and water cannot enter aquifers fast enough. In the face of extreme precipitation, California needs to store water more effectively. For instance, the state could construct more reservoirs, directly increasing storage capacity.

Secondly, California must improve its methods of capturing storm water. When water falls too fast and creates a hazard, the state tries to remove it from the land as quickly as possible, allowing it to drain into the Pacific Ocean. Rather than wasting so much stormwater, California should instead create floodplains and permit the stormwater to slowly accumulate in aquifers, replenishing groundwater.

Finally, more water treatment facilities must be constructed and properly maintained to keep up with the increased collection and storage of stormwater.

If California acts quickly, it might just survive the worst of climate change.