Unrelenting Winter Warmth Could Herald Alaska’s Future
The first 100 days of 2016 were record warm for many spots around Alaska, continuing a pattern of warmth that has gripped the state over much of the last three years and looks to continue for at least the next few months.
The prolonged period of decidedly unusual balminess — the result of a particular combination of climate factors (and a nudge from long-term global warming) — comes with concerns for an earlier wildfire season, salmon die-offs and damage to roads and other infrastructure as seasonally frozen ground thaws early.
— NWS Juneau (@NWSJuneau) April 11, 2016
And such winters are only going to become more and more common as greenhouse gases continue to build up in the Earth’s atmosphere.
The National Weather Service noted on Monday that this Jan.1 through April 9 was the warmest such period on record in Juneau, Sitka, and Ketchikan, as well as other spots.
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Earlier this month, the NWS’s parent organization, the National Oceanic and Atmospheric Administration, announced that the state as a whole was having the warmest year-to-date on record through March.
On March 31, Klawock, in southeastern Alaska, hit 71°F, the warmest March temperature ever measured in the state, while the temperature in Fairbanks failed to drop below -30°F (-34°C) during the winter for only the second time on record.
There were hardly any extended periods of cold during the winter, Rick Thoman, climate science and services manager for the NWS’s Alaska region, said. “Not even for a week, not even for three days.”
The reason behind the “unmitigated persistence” was “the convergence of a whole bunch of things that tend to make Alaska warm,” Thoman said. These include a strong El Niño, a fairly strong phase of a related climate pattern, called the Pacific Decadal Oscillation, and “very low sea ice coverage in the Bering Sea” accompanied by warmer waters off Alaska’s coast.
Even with El Niño waning, the picture doesn’t look to change anytime soon. The outlook from NOAA’s Climate Prediction Center points to continued warmth through the spring throughout the state.
Come summer, the seas will still be warm (because the ocean changes temperature much more slowly than land), which is expected to keep coastal areas warm, Thoman said.
It is possible that the decaying El Nino could lead to a La Niña pattern (featuring colder than normal tropical Pacific Ocean waters) come fall, which could finally break the warm winter pattern for Alaska. During La Niñas, unusually warm winters are less likely and winter weather tends to be much more variable on the whole, with weeks of warmth followed by weeks of cold, Thoman said.
Ahead of Schedule
But after the tepid winter this year, “winter snow melt is well underway” in the southern half of the state, Thoman said. Fairbanks had its third earliest loss of its snowpack on record, while Anchorage “hardly kept a snowpack this winter,” he said.
That early snowmelt has left behind dead and dormant plant matter to dry out, increasing worries that the wildfire season will begin earlier than normal. (The early snowmelt doesn’t necessarily mean a more intense fire season; a season’s severity depends more on how stormy weather during the season is, because most bad wildfires in Alaska are caused by lightning.)
— NWS Fairbanks (@NWSFairbanks) April 10, 2016
An early snowmelt could also imperil salmon, as key streams become too warm later in the summer without an influx of cold meltwater.
The jumpstart on spring has also meant that grizzly bears have emerged early from hibernation and some migratory birds have returned ahead of schedule, Thoman said.
“It really feels like we’re three or four weeks ahead of where we ought to be and really it’s felt like that for awhile,” he said.
The warmth also meant that the layer of the soil that freezes and thaws with the seasons was two months late in freezing this year and won’t be frozen for long. With three years of such warmth, it is more likely that sinkholes will open up and the ground below roads will crumble, Vladimir Romanovsky, a permafrost researcher at the University of Alaska Fairbanks, said.
All of these effects will become increasing concerns in the years and decades to come because in a warming world “these kinds of winters become more likely,” Thoman said. And Alaska is warming at twice the rate of the rest of the U.S., a sign of the rapid heating of the Arctic in general.
In fact, the impact of warming on Alaska winters is already clear: “A cold winter now is a ‘meh’ winter in the 1950s,” Thoman said.