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In terms of thickness, sea ice has been reduced by more than one meter in many places, such as north of Greenland and the Canadian Archipelago, all in the time span of just one month.
The dramatic fall in sea ice concentration also becomes apparent when comparing recent sea ice concentration (July 18, 2015, above right) with sea ice concentration back in May 2015 (image right, May 1, 2015).
This dramatic decline of the sea ice in 2015 is the result of a combination of factors, including:
- High levels of greenhouse gases over the Arctic Ocean, as illustrated by the image below, showing that on July 17, 2015 (pm), levels as high as 2512 parts per billion were recorded at 6,041 m (19,820 ft) altitude, while mean methane levels were 1830 parts per billion at this altitude.
- High levels of ocean heat, as illustrated by the image below showing high sea surface temperatures off the east coast of North America; much of this ocean heat will be carried by the Gulf Stream into the Arctic Ocean over the next few months.
- High air temperatures over North America and Siberia extending over the Arctic Ocean, as illustrated by the image below showing a temperature of 23.1°C (73.7°F), recorded on July 19, 2015, at Banks Island, in the Canadian Archipelago (green circle).
- Wildfires triggered by these heatwaves resulting in darkening compounds settling on snow and ice, as illustrated by the image below showing smoke covering a wide area on July 19, 2015, from the east Siberia over North America to the southern tip of Greenland.
- Very warm river water running into the Arctic Ocean, as illustrated by the image below, showing sea surface temperatures as high as 19°C (66.2°F) off the coast of Alaska on July 12-15, 2015.
The Climate Reanalyzer image below shows the high sea surface temperature anomalies in the Pacific Ocean, and where water enter the Arctic Ocean through the Bering Strait, on July 19, 2015.
With still two months of melting to go before the sea ice can be expected to reach its minimum for 2015, the threat of sea ice collapse is ominous. The Arctic-News Blog has been warning for years about the growing chance of a collapse of the sea ice, in which case huge amounts of sunlight that previously were reflected back into space, as well as heat that previously went into melting the ice, will then instead have to be absorbed by the water, resulting in a dramatic rise of sea surface temperatures.
More open water will then come with an increased chance of storms that can cause high sea surface temperatures to be mixed down all the way to seafloor of the Arctic Ocean, which in many cases is less than 50 m (164 ft) deep. This is the case for the East Siberian Arctic Shelf, where experts estimate that huge amounts of methane are contained in subsea sediments. Already now, sea surface temperatures as high as 10°C (~50°F) are recorded there, as illustrated by the image below.
Massive amounts of ocean heat will be carried by the Gulf Stream into the Arctic Ocean over the next few months. The combined result of high sea surface temperatures being mixed down to the seafloor and the ocean heat entering the Arctic Ocean from the Atlantic and Pacific Oceans can be expected to result in dramatic methane eruptions from the Arctic Ocean seafloor by October 2015.
The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan.