Atmospheric rivers play crucial role in sea ice loss

New research out of Penn State University found the increased rate of atmospheric river events occurring in the Arctic accounted for as much as an entire third of all winter sea ice decline.

AUSTIN (KXAN) — As temperatures across the globe continue to climb, much of the ice in the Arctic continues to melt. This, in return, creates a feedback loop that is responsible for the Arctic warming up to three times faster than the rest of the globe.

Scientists however have found warming temperatures do not bare the sole responsibility of sea ice melt in the Arctic. New research out of Penn State University found the increased rate of atmospheric river events occurring in the Arctic accounted for as much as an entire third of all winter sea ice decline.

Atmospheric rivers are narrow corridors of concentrated moisture or water vapor in the atmosphere and are responsible for producing powerful, long-duration storms and copious amounts of rain and snow. Global warming has been found to increase the number of atmospheric events over the past few decades, but more so in mid-latitude locations such as California.

Using satellite observations and climate model simulations, this study found the Arctic, the Barents and Kara seas off the northern coasts of Norway and Russia area in particular, is also experiencing more frequent atmospheric river events. They found the timing of these storms was also arriving at a critical time of the year: winter. This is problematic because this is when much of the ice in the Arctic needs to regrow to compensate for ice that was lost through melting during the relatively warm summer months.

We see normal seasonality variability of sea ice growth and loss throughout a given year. In general, sea ice that retreats in the summer would eventually regain and recover during the freezing cold winter months. But with global warming tipping the scale and more atmospheric river events, the winter months often don't recover enough to compensate for the ice lost during the summer, resulting in a net loss of ice. On average, the overall average sea ice extent in the Arctic has been decreasing over the past 50 years.

How do atmospheric rivers produce sea ice melt?

1. Atmospheric rivers transport warmer-than-normal temperatures with them.
2. Increased water vapor and clouds over the Arctic trap heat from escaping into space, causing further warming.
3. More precipitation is falling as rain that would otherwise fall as snow.
4. Latent Heat Release: energy released when water vapor condenses to form liquid droplets.

The scientists used satellite remote sensing images and found the sea ice response following atmospheric river storms was dramatic. The extent of the sea ice retreated almost immediately, and in many cases persisted for up to 10 days after an atmospheric river event.