Everywhere I looked, there was water...

On February 13, 2019, I was riding in the back seat of a white pick-up truck surveying the land - I could not recognize any of the normal features I had seen when I had toured the Town earlier that week during a dry-ish day. Everywhere I looked, there was water. I’m not talking drops of rain easily held off by an umbrella; it was like the atmosphere turned on a hose. To make matters worse, the tide was rising and the bay water was overtopping levees and natural features, adding to what felt like a giant swimming pool atop the Town. The sheer volume of water coming at me was a new experience for this Colorado native and now Southern Californian resident.

What was happening? It was an atmospheric river, so called because they can carry so much water that they are likened to a river in the sky. Tropical moisture near Hawaii is trapped by the atmosphere, and moves west towards California. Once the atmospheric river encounters mountains, water cools and condenses, getting heavier, and falls as rain or snow. Atmospheric rivers can carry as much water as 15 Mississippi Rivers![i]

Unfortunately, this won’t be the last time Corte Madera sees major flooding. As the climate warms, sea levels will rise and the atmosphere will be able to hold more water. Climatologists agree that we’ll see more atmospheric rivers—likely a doubling by the end of 21st century![ii] Climate projections don’t always point to the same future, but one thing nearly all projections have in common is an increase in the number of atmospheric rivers, and a decline in the kind of “normal” storms we are used to. In the future, we are looking at more dry days, punctuated by major storms caused by atmospheric rivers.[iii]

This presents a problem because we’ve spent a century or more building up infrastructure for flood control in an attempt to take the peaks off of what was historically the worst floods and the highest high tides. As climate change continues, I think we might find it harder to control floodwaters. I wonder if a changing climate might bring California closer to the way its natural systems evolved pre-human infrastructure – where there was more space, which allowed for bigger areas to absorb floodwaters. For now, as a community, as a region, as a planet, we are tasked with looking at how we might achieve balance with a changing climate. What I do know is that we have a lot to learn.

-Leslie Regan


Sources:

 

[i] Los Angeles Times. National Weather Service, Scientific American. February 13, 2019.  https://www.latimes.com/local/lanow/la-me-atmospheric-river-rain-california-explainer-20190213-story.html

[ii] Pottinger, Lori. Public Policy Institute. California Depends on Rivers—in the Air. December 8, 2015. https://www.ppic.org/blog/california-depends-on-rivers-in-the-air/

[iii] Public Policy Institute. California Depends on Rivers—in the Air. December 8, 2015. https://www.ppic.org/blog/california-depends-on-rivers-in-the-air/

 

Sascha Petersen