Thursday, 3 August 2017

The Arctic Ocean is warming up fast and this is melting the sea ice from below.

Arctic sea ice may well be gone by September 2017

The Arctic Ocean is warming up fast and this is melting the sea ice from below.

2 September, 2017

Sea surface temperature anomalies are well above 8°C (14.4°F) in several parts of the Arctic Ocean. 

The image on the right shows sea surface temperature anomalies from 1961-1990 for the Arctic (60°N - 90°N) on August 2, 2017.

Global sea ice extent is at a record low for the time of the year, as illustrated by the graph below, by Wipneus. Lower sea ice extent means that less sunlight is reflected back into space.

Arctic sea ice extent in 2017 is shrinking along a path much similar to the years 2012, 2016 and 2007, when sea ice reached 1st, 2nd and 3rd place, respectively, regarding lowest extent.

While sea ice extent may look similar to these other three years, sea ice thickness has fallen dramatically over the years, as illustrated by the image below, showing Arctic sea ice thickness (in m) in July 31, 2012 (left) versus thickness on July 31, 2017 (right).

The animation on the right shows sea ice has getting thinner recently, with especially the thicker sea ice disappearing fast.

One of the reasons for this dramatic shrinking of the thicker sea ice is the ever warmer water getting pushed into the Arctic Ocean along the Gulf Stream. This is melting the sea ice from below. 

Warming of the Arctic Ocean heats up the air over the Arctic Ocean, as illustrated by the image below.

The above image shows a 365-day surface temperature anomaly. The change over time is also illustrated by the animation on the right.

On average, surface temperatures over the Arctic Ocean have been more than 2.5°C (or 4.5°F) warmer than in 1981-2010. The warmer air is now melting the sea ice from above, as temperatures over the Arctic have risen above the freezing point.

High temperatures over the Arctic Ocean means that precipitation no longer takes the form of snow, but instead falls in the form of rain.

High temperatures of the surface of the ocean combined with strong winds makes that a lot of moisture is rising from the sea surface to the atmosphere. The image below shows how strong winds are pushing warm and moist air through the Bering Strait on July 31, 2017 at surface level (left), at 700 hPa (center) and at 250 hPa (right), where the jet stream used to separate the cold air in the Arctic from the warmer air further south. As the image shows, the jet stream is getting out of shape, at places crossing the Arctic Ocean.

The image below shows trends for both Arctic and Antarctic sea ice area pointing downward.

When looking at sea ice volume, zero sea ice in September 2017 is within the margins of the trendline below on the right.
[ Arctic sea ice, gone by Sept. 2017? ]

Given the speed at which many feedbacks can kick in and the interaction between warming elements, Arctic sea ice volume may well be gone by September 2017.

The low sea ice volume means that there is very little sea ice left to act as a buffer this year. Therefore, a huge amount of heat will not be able to be consumed this year in the process of melting ice and will instead speed up warming of water of the Arctic Ocean. 

Less sea ice additionally means that less sunlight will be reflected back into space, and this heat will instead further speed up Arctic warming.
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Where can all this extra heat go? Sea ice is expected to start sealing off much of the surface of the Arctic Ocean by the end of September 2017, which will make it harder for heat to escape the Arctic Ocean by entering the atmosphere.

The danger is that much of the extra heat will instead reach sediments at the seafloor of the Arctic Ocean that contain huge amounts of methane in currently still frozen hydrates.

The image above shows that methane reached levels as high as 2583 ppb on July 31, 2017. 

The image also shows high methane levels over Antarctica where hydrate destabilization also appears to be taking place, as discussed in an earlier post.

The situation is dire and calls for comprehensive and effective action, as described at the Climate Plan.

1 comment:

  1. 8 degrees celsius converts to 46.4 degrees farenheit, not 14.4 as stated.