Weather

Alaska’s new weather normal is warmer and wetter, NOAA says in once-a-decade data update

A once-a-decade data update released this week again shows Alaska experiencing climate change more acutely than much of the Lower 48.

A report by the National Oceanic and Atmospheric Administration defines the new normal climate for the nation based on data from the last 30 years.

In Alaska, the normal temperature has risen nearly 1 degree Fahrenheit since the last report was issued with data up to 2010, according to the National Weather Service. Temperatures in the Lower 48 rose by about 0.5 degrees Fahrenheit since the last report.

“This is reflective of our warming environment,” said Rick Thoman, a climatologist at the University of Alaska Fairbanks. “The biggest changes in northern and Western Alaska are reflecting the changes in sea ice, the seasonality of sea ice, which then in turn affects ecosystems, subsistence activities, marine tourism, national security.

“The normals by themselves are one thing, but it’s what they’re reflecting, that’s the larger impact,” Thoman said.

The 30-year normal is recalculated once every decade. The new normal is now defined without data from the 1980s and includes data from 2010 until 2020, Thoman said.

The data is used to provide information about typical climate conditions for comparison in weather and forecasts.

“In general, what we see is that almost everywhere in Alaska has warmed at least a little bit,” Thoman said. “In northern and Western Alaska the changes are very dramatic, especially considering that 20 of the 30 years are exactly the same.”

The normal temperature in Utqiagvik on the Arctic coast has increased about 2 degrees Fahrenheit since the last set of data was released.

The temperature increases are tied in part to distinct changes in the extent of sea ice, Thoman said. There has been significantly less sea ice in recent years, with historic lows recorded in the Bering Sea. Shrinking sea ice is caused by warmer ocean waters and overall warming in the Arctic blamed on a worldwide increase in greenhouse gases in the atmosphere caused by human activity.

[‘Granddad’s Arctic isn’t coming back’: Northern Alaska is transitioning to a biologically changed landscape]

The lack of sea ice causes an ecosystem change in the northern Bering Sea that makes it more difficult for subsistence activities like harvesting and hunting from the sea, Thoman said.

“From the climate system, it is affecting all of Alaska,” he said. “In the fall, without that sea ice and just sea water there, it’s pumping tremendous amounts of heat into the atmosphere and kind of acting as a heating pad.”

Normal levels of precipitation have also changed, Thoman said. Many areas of the state are seeing increasing precipitation, although the location is much more varied. A similar trend was seen in Lower 48 data too.

Some of the increase in precipitation can be linked to the “overall warming and ‘wetting’ of the atmosphere that’s occurred as rising temperatures enhance evaporation of water from the ocean and land surface,” according to a NOAA analysis.

In places where normal precipitation has not changed significantly, the seasonal normal is shifting, with less snow in the fall and more snow during the winter, Thoman said.

“With less snow average in the fall, in some cases that is offset by more snow during the winter,” Thoman said. “So the whole season doesn’t change, but it’s kind of a shortening of the snow season. ... It’s being compressed into the winter season.”

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