Check it out: Atmospheric Rivers in the Northwest

By Janelle Christensen, USDA Northwest Climate Hub

Colored image of the North Atlantic, showing the river of moisture in warm colors
An atmospheric river noted in green and yellow band going into the West Coast, February 2004. Image: NOAA Physical Sciences Laboratory Advanced Quantitative Precipitation Information.

Atmospheric rivers are a buzzword right now. A few years ago, I had never heard the term, and now I hear it on the news and tossed about in everyday conversation with colleagues and friends. Although atmospheric rivers are not a new phenomenon, they were only given a name in the 1990s. I grew up knowing about the Pineapple Express, one of the largest ones that hits the West Coast every year, but like many people, I did not know that this was a common atmospheric event. Because I’m hearing the term more and more, I decided to look into the current research about atmospheric rivers and what impacts climate change will have on them.

More than our understanding of the existence of these rivers, we have also started to understand and quantify the differing severities of these events. Atmospheric rivers can range from primarily beneficial to primarily hazardous. Many of them bring beneficial water to the West Coast and help to relieve drought conditions. However, as we have seen recently in California, some atmospheric rivers can be very damaging. This is especially true when they hit places that already have saturated soils or places that do not have good drainage and cannot move so much water so quickly.

We have also started to understand how much more damaging atmospheric rivers may be in the future. As the planet warms, more water vapor will result in longer and wider atmospheric rivers. These could result in more flooding and larger landslides. The effects of these rivers could also compound other effects of climate change, such as larger and more frequent wildfires, which leave slopes of exposed soil vulnerable to significant erosion events. As climate change affects the West Coast, it will be important to plan for the increased severity of atmospheric rivers, and hopefully reduce some of the damage they will cause.

To read more about atmospheric rivers, how our understanding of them has changed, how we quantify them, and what they will look like in the future, check out this article I wrote for the USDA Northwest Climate Hub.


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