From unseasonal rainfall to early flooding and record heat, this summer has seen a lot of strange and concerning weather events across the Northwest Arctic and North Slope. That’s not changing as summer comes to an end.
At the end of July, Utqiaġvik broke its record for the most consecutive number of days above freezing. It has continued to break that record every day after. By the end of August, Utqiaġvik had seen 63 consecutive days in which its lowest temperature was higher than 36 degrees.
The streak has continued in September.
“Without any air temperatures below freezing, this is, of course, building on the overall warmer temperatures, so it’s deepening the thaw of the active layer,” said Rick Thoman, of the Alaska Center for Climate Assessment and Policy at the University of Alaska Fairbanks. "In the decades-long scale, it contributes to the loss of permafrost.”
That’s along with a whole host of other impacts the warm temperatures are having across the Arctic. Of course, the complete loss of permafrost is not going to happen extremely soon, Thoman said.
“But everybody knows the active layer is getting much deeper in the summer. It's having impacts now on infrastructure,” he said. "With no temperatures at all below freezing, that will just exacerbate those problems.”
The previous record for lows above freezing was 28 days in 1951, he noted. This is more than double that.
Perhaps counterintuitively, daily highs and lows show different things about our climate, Thoman explained. That’s why it’s important to track both.
"In particular, low temperatures are much more sensitive to things like increasing greenhouse gases, which, obviously, people would immediately think about carbon dioxide, but actually, in the more immediate level, it’s increasing water vapor,” he said. "Higher humidity, more water vapor in the air, is very effective at keeping temperatures higher at night.”
With 24 hours of sun in the summer on the North Slope, that equation changes a bit. In non-Arctic places in June, there’s no solar heating at night, so factors like water vapor take on greater importance. It still has an effect on air temperature in Utqiaġvik, given that the sun is still low in the sky around the hours of solar midnight, but not as great an effect as it would elsewhere.
So, in Utqiaġvik, the higher low temperatures predominantly show us the effects of high sea surface temperatures. That’s one of the most significant contributors to air temperature in the area.
“In the summer in Utqiaġvik, temperatures are going to be controlled much more by what’s going on on the Chukchi Sea and on the other side, in the far western Beaufort,” Thoman said. "Is there ice cover? If it’s not ice, is it broken ice? Is it open water? If it’s open water, what’s the water temperature? Early in the summer, things like when lake ice goes out will be an important factor in determining low temperature as well.”
Sea surface temperatures have been well above normal this summer. In fact, this year is on track to have the highest or second highest summer sea surface temperatures across the eastern and central Bering Sea, north to the Arctic and even across much of the Gulf of Alaska, based on data from the National Oceanic and Atmospheric Administration.
"With ocean surface temperatures in the mid-40s, with the wind off the water, there’s no way to get it very far down in the 30s,” Thoman said. "Now, we’re at the time of year, if we can get Utqiaġvik’s narrow land wing from east southeast to about due south where the wind is blowing off the land, sure it can get colder than the water. But that’s a narrow window. The big thing here is it’s really reflecting how warm the oceans have been.”
The second part of that is how wet the summer has been in Utqiaġvik.
From July 31 to Aug. 1, nearly an inch of rain fell in the community. Meteorologists say Utqiaġvik has already seen more than double its normal summer precipitation this year.
That means there have been a lot of clouds with high relative humidity and warmer temperatures, all of which contribute to air temperatures staying above freezing, Thoman said.