The left map shows temperatures of 40 degrees below zero moving down into North America from the Arctic, while temperatures in much of Alaska are above freezing point. The right map shows temperature anomalies over large parts of North America at both the top end (red) and the bottom end (purple) of the scale. Temperature anomaly forecasts for the week from Feb 19 to 26, 2015, feature in the video below.
Below is an update showing operational temperature anomalies recorded on February 23, 2015.
As parts of North America experienced record cold, part of Alaska was more than 20°C (36°F)
warmer than it used to be (compared to 1985-1996). And despite the cold weather in parts of Canada and Greenland, the Arctic as a whole is forecast to reach, on February 26, temperature anomalies as much as 3.32°C (≈6°F) above what temperatures used to be from 1979 to 2000 (Climate Reanalyzer forecast data).
What has caused our climate to change in this way? The image below shows that the jet stream, which once used to move over North America horizontally, has become more wavy, pushing warm air north on the left, while drawing cold air from the Arctic south on the right.
Importantly, while the jet stream is becoming more wavy or elongated vertically, the speed at which it crosses the oceans can increase dramatically. This can be the case where low temperatures over land and high sea surface temperatures combine to create huge temperature differences that drive up the jet stream's speed over oceans.
This is illustrated by the image below showing the Jet Stream reaching speeds as high as 410 km/h (or 255 mph) at the green circle near Greenland on January 9, 2015 (left), and speeds as high as 403 km/h (or 250 mph) at the green circle near Greenland on February 20, 2015 (right).
Similarly, the Polar Vortex can reach high speeds, driving cold air downward over North America and driving warm air upward over Greenland and the North Atlantic.
The image below shows the Polar Vortex reaching speeds as high as 346 km/h (or 215 mph) at the green circle near Svalbard on January 18, 2015 (left), and speeds as high as 316 km/h (or 196.4 mph) at the green circle over the Arctic Ocean on February 9, 2015 (right).
Almost one year ago, the Polar Vortex also reached speeds as high as 410 km/h (or 255 mph), as discussed in an earlier post. Changes to the polar vortex and the jet stream are caused by emissions, and the situation looks set to deteriorate even further.
Above image illustrates that, on February 16, 2015, waves higher than 10 m (32.81 ft) were recorded off the east coast of North America and south of Iceland, while waves as high as 8.15 m (26.74 ft) were recorded in between Norway and Svalbard.
The air that is moving north is much warmer than it used to be, as sea surface temperatures off the east coast of North America are much higher than they used to be (image left and as discussed in an earlier post).
Strong winds increase the volume of warm water that the Gulf Stream carries into the Arctic Ocean. They can also cause rain storms that can devastate Arctic ice and glaciers
Arctic sea ice currently has about the lowest extent for the time of the year since satellite measurements started in 1979.
The image below shows that, on February 17, 2015, Arctic sea ice had reached an extent of merely 14.406 million square kilometers.
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| click on image to enlarge |
Below is a 30-day animation showing sea ice thickness (in m) up to February 22, 2015 (and forecast up to March 2), from the U.S. Naval Research Laboratory.
As the Arctic's snow and ice cover decline, more sunlight gets absorbed that previously was reflected back into space. All this adds up to a very dangerous situation, since huge amounts of methane are contained in sediments under the seafloor of the Arctic Ocean, and they can get destabilized as the water warms up.
In conclusion, feedbacks make that the Arctic is warming more rapidly than the rest of the globe and they threaten to trigger huge methane eruptions from the seafloor of the Arctic Ocean.
Methane concentrations over the Arctic Ocean are very high at the moment. The image below shows the very high peak methane levels that have recently been recorded, against a background image showing high methane levels over the East Siberian Arctic Shelf on February 20, 2015.
The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan blog.
Post by Sam Carana.
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