In changing climate, Alaska faces risk of extreme precipitation

Alaska has been experiencing unprecedented extreme weather, but what does that really mean for Alaskans? During the past week, 2 to 4 feet of snow fell widely across the Southcentral part of the state, seriously disrupting pre-Christmas activities for more than half of Alaskans. At the same time, record-breaking high temperatures on the North Slope and repeated rain and mild temperatures melted the early winter snowpack in the Bering Strait. 

Over the past three years heavy precipitation events, in some cases of historic proportions, struck in many parts of the state. It was only two years ago this month that torrential rains caused the fatal landslide in Haines. Last year, multiple storms brought repeated heavy rains to Northwest Alaska and kept the Noatak River running high all summer, causing severe river bank erosion and threatening Noatak community waste disposal and infrastructure. Sometimes the precipitation has been the “wrong type for the season,” such as the heavy (freezing) rain that affected a wide swath of Southwest Alaska and the Interior in late December 2021. And, 2022 will go down as the wettest year on record for both Anchorage and Juneau. These events have significant consequences for communities for months and years afterward. 

When people think of Alaska’s changing environment, their first thought is likely related to increasing temperature; but, Alaska’s recent experiences should compel us to seriously consider the increasing risk of extreme precipitation. The 2022 NOAA Arctic Report Card, released Dec. 13, includes an essay led by John Walsh, chief scientist with International Arctic Research Center at the University of Alaska Fairbanks, showing an increase of both total precipitation and extreme precipitation in the Arctic. 

Scientists expect more frequent extreme precipitation events, both rain and snow, in Alaska as temperatures increase and oceans warm. Warming oceans evaporate more water into the atmosphere and a warmer atmosphere can hold more water. This falls out as more snow in Alaska where temperatures are still, on average, below freezing part of the year. Recent work by the International Arctic Research Center adds a twist to the expected increase in precipitation. 

Researchers found that though total Alaska seasonal snowfall has changed little over the past 50 years, more of the snow is falling in mid-winter and less in autumn. Very heavy snowfall impacts more than just the hours or few days following the event. Snow accumulated over weeks or months can produce extreme snow loads that can collapse roofs and set the stage for catastrophic mountain avalanches. 

Alaskans need to seriously consider the threat of heavy snow and rain, from the potential impacts of individual storms to the cumulative effects of stormy weeks and seasons. Future extremes may be beyond what individuals recall or even what is within the century-long climate record. These considerations are not only a matter of convenience, but for the health and safety of all Alaskans. Road and runway conditions must not hinder emergency services or reliable transport of goods and services. Living and working in areas that are, or will potentially be, prone to avalanches needs to be evaluated in light of present and future risk. 

Because rain and snow events that cause widespread or serious disruption are relatively infrequent at any one place, there will be immense budgetary pressure to make do with fewer resources than will be needed to successfully handle such events. Those will be societal decisions ultimately made through the political process, but extreme precipitation events and their impacts will affect both rural and urban Alaskans. While we don’t know far in advance exactly when or where these extremes will occur, without informed preparation the resulting impacts are sure to be severe. The best time to plan and take action was yesterday. The second-best time to prepare for the next “never happened before” event is right now. 

This commentary was originally published in the Alaska Beacon.