Alaska’s exceptional summer continues.
The most rapidly changing state in the U.S. is free of sea ice within 150 miles of its shores, according to high-resolution sea ice analysis from the National Weather Service. The big picture is clear: After an Arctic summer with well above-average temperatures, warmer seas, and a historic July heat wave, sea ice has vanished in Alaskan waters.
“Alaska waters are ice free,” said Rick Thoman, a climate specialist at the Alaska Center for Climate Assessment and Policy.
“This is definitely an extreme year — even by more recent standards in a changed Arctic,” noted Walt Walt Meier, a senior research scientist at the National Snow and Ice Data Center.
In the continually warming Arctic, sea ice has completely melted around the Alaskan coast before, but never this early. “It’s cleared earlier than it has in any other year,” said Thoman.
Arctic sea ice has been either been at record lows or flirting with record lows throughout much of the summer. “I’m losing the ability to communicate the magnitude [of change],” Jeremy Mathis, a longtime Arctic researcher and current board director at the National Academies of Sciences, told Mashable in June, when sea ice levels were at their lowest point in the satellite record for that period. “I’m running out of adjectives to describe the scope of change we’re seeing.”
Even during the winter, historically ice-clad seas were nearly free of ice. The Bering Sea, in early March, was open ocean. That’s not normal for winter. “It’s normally pretty much covered completely with ice,” said Meier.
“I’m losing the ability to communicate the magnitude [of change]”
A fundamental problem is that most of the sea ice around Alaska, and in the greater Arctic, is young. The older, thicker, multiyear sea ice has already melted away by warmer ocean and air temperatures. (Temperatures this July the seas around Alaska, the Beaufort and Chukchi seas, were some 9 or 10 degrees Fahrenheit above average, noted Meier.) Only the thin, more vulnerable sea ice remains.
“The loss of the multiyear ice is really a big driver here,” emphasized Thoman. “First-year ice is much more susceptible to the vagaries of weather.”
The weather, swayed by climate, is often warmer than it was last century. The resulting, relentless ice loss is one of the most conspicuous results of a rapidly heating climate. Just like glaciers.
“This is due to the long-term warming of the Arctic,” Zack Labe, a climate scientist and PhD candidate at the University of California, Irvine, explained in June. “Air temperatures are now rising at more than twice the rate of the global mean temperature — a phenomenon known as ‘Arctic Amplification’.”
The Arctic’s warming is especially amplified by the ocean. When reflective, white sea ice vanishes, the darker ocean absorbs solar energy, rather than reflecting it back into space. To boot, this warmth then mixes around with other waters, warming them too, explained Thoman.
It’s a vicious cycle. And the consequences are ramping up.
“Things are not necessarily gradual,” said Thoman, referencing the big changes occurring in and around Alaska ”When thresholds get crossed, changes occur in a hurry.”
from Mashable! http://bit.ly/2YuJcbo