(Image Source: Barrow Ice Cam)
Barrow’s sea ice has borne a number of pretty severe insults over the past week. First, an Arctic heatwave sent Alaskan temperatures soaring to 98 degrees (F) in the interior, the highest temperatures ever recorded for the state. This heat pulse extended far above the Arctic Circle pushing temperatures at Barrow as high as 65 degrees (F) even as flows of warm water flooded into the Chukchi Sea from Alaska’s baked center. These high temperatures spurred an early break-up of Barrow sea ice last week. A break up that proceeded about three weeks ahead of schedule. Then, an ice-melting rain settled in, pelting the sea ice over the past three days.
Now the offshore ice is simply gone.
As you can see in the image above, huge sections of near-shore ice are melted and broken with large areas dominated by dark Arctic water. But offshore is were the greater effects have occurred. Over the past 24 hours, the off-shore ice has shrunk back and now only open ocean is visible on the horizon.
Ice break-up at Barrow occurs when off-shore ice at distances greater than 200 meters from shore begins to move. This event usually occurs on about July 8th. This year it happened on June 20th. Now, less than a week later, the ice that first broke has disappeared.
It will take a little longer for the near-shore ice to melt out. But the most important ice off Barrow — the sea ice — is now departing, retreating into a pack that is rapidly receding from the Chukchi Sea.
You can view the retreat of off-shore ice in the radar sequence below:
Note the ongoing parallel motion to shore and then the lifting away of sea ice during the last sequence.
These radar shots were taken on June 24. So final recession of sea ice occurred only four days after break-up.
Today’s radar shots from Barrow show only small chunks of sea ice remaining from a once-large pack.
(Image source: Barrow Ice Cam)
We can now say farewell to significant sea ice at Barrow, Alaska for the rest of this summer. Melt will now begin to proceed past the Chukchi Sea and into the Beaufort and East Siberian. This will likely have significant impacts once Beaufort ice begins to break as a Gyre in the center of the Sea begins to increase ice mobility and melt. Already, anchors have been weakened by both rapid melt in the Chukchi and by a large pulse of warm floodwater flowing out of Alberta via the Mackenzie Delta. This pulse of water is a direct result this week’s Canadian floods. So we’ll have to see what impact these warm flood waters have on the shore area of the Beaufort over the coming week.
Last of all, it is worth mentioning that this year’s Persistent Arctic Cyclone has tended to push more ice into the Beaufort. Over past years, the Beaufort has been much more vulnerable to melt come late July through mid-September. With early melt rapidly proceeding from the Chukchi and with areas in Canada and Alaska vulnerable to floods and heatwaves, this critical region of buffering ice will increasingly come into play as melt season progresses. The new dynamic of a PAC hollowing out the central ice as Beaufort melt and ice motion begin to crank up raise the potential for a number of volatile outcomes.
So eyes will shift to the Beaufort as these new potentials emerge.