Atmospheric river that ravaged Yellowstone National Park is part of climate change pattern

Unprecedented rainfall leading to unprecedented flooding closed Yellowstone National Park on Monday, a turn of events that scientists say has all the hallmarks of climate change.

After the park received 2.5 inches of rain and nearby mountains were hit with as much as 5 inches that sped up snow melt, a torrent of floodwaters washed out roads and bridges throughout Yellowstone.

“Due to record flooding events in the park and more precipitation in the forecast, we have made the decision to close Yellowstone to all inbound visitation,” Yellowstone superintendent Cameron Sholly said in a statement.

The extreme rainfall quickly melted mountain snow, resulting in runoff that caused streams and rivers to overflow their banks.

“It’s a lot of rain, but the flooding wouldn’t have been anything like this if we didn’t have so much snow,” Cory Mottice, a meteorologist with the National Weather Service, told the Associated Press. “This is flooding that we’ve just never seen in our lifetimes before.”

High levels of water in the Gardner River in Yellowstone National Park
The raging Gardner River does damage to a road in Yellowstone National Park. (National Park Service/Handout via Reuters)

The same so-called atmospheric river, or tropical moisture, that dumped rain on Yellowstone set June rainfall records in Seattle, which received more than an inch on June 9, and pushed the Columbia River in Oregon to near flood stage.

Much recent scientific research has linked climate change to extreme weather, and this past week has offered yet more evidence of how that connection can play out. Daniel Swain, a climate scientist at the University of California, Los Angeles, tallied some of the effects witnessed over the past week.

Studies have shown that the increase in ocean surface temperatures, as well as air temperatures, have increased the amount of atmospheric moisture and resulted in an uptick in the amount of rainfall to the Pacific Northwest delivered via atmospheric river storms.

“Extreme precipitation is increasing worldwide. Across the United States, observational data shows an increase in the intensity and frequency of extreme precipitation events,” Climate Signals, a nonprofit that tracks climate change developments, says on its website. “This is because warmer air has the capacity to hold and release more moisture. For each 1°C of warming, saturated air contains seven percent more water vapor. Therefore, a given volume of warmer air has the capacity to drop greater amounts of rain and snowfall than the same volume of cooler air.”

Flooding on June 14 in Livingston, Mont.
The Yellowstone River has hit historic high levels due to rain and snow melt from the mountains in and around Yellowstone National Park. (William Campbell/Getty Images)

The atmospheric river that broke rainfall records in parts of Washington before wreaking havoc in Yellowstone National Park was classified as a maximum Category 5 event on a scale developed by the Center for Western Weather and Water Extremes in San Diego.

Atmospheric rivers do not typically hit the western U.S. in late spring or summer, nor do they often measure 5 on the AR scale. But thanks to climate change, however, new records are being set with alarming regularity.

“It’s remarkably unusual to have an AR5 [Category 5 atmospheric river] in June in the Northwest,” Marty Ralph, director of the Center for Western Weather and Water Extremes, told the Washington Post.

For Yellowstone and other parts of the world where climate change is increasing the frequency and power of atmospheric rivers, the anxiety of not knowing what the future holds has become routine.

“We will not know timing of the park’s reopening until flood waters subside and we’re able to assess the damage throughout the park. It is likely that the northern loop will be closed for a substantial amount of time,” park superintendent Sholly said in his statement.