Three kinds of warming in
the Arctic
26
February, 2016
The
Arctic is prone to suffer from three kinds of warming. Firstly, the
Arctic is hit particularly hard by emissions, as discussed in earlier
posts such as this one and this one.
Secondly,
warming in the Arctic is accelerating due to feedbacks, as discussed
on the feedbacks page. Many such feedbacks are related to decline of
the snow and ice cover in the Arctic, which is in turn made worse by
emissions such as soot.
Thirdly,
the most dangerous feedback is release of methane from the Arctic
Ocean seafloor, due to hydrates getting destabilized as heat reaches
sediments
Last year, Arctic sea ice reached its maximum extent on February 25, 2015. This year, there's a lot less sea ice in the Arctic than last year. The difference is about 300,000 square km, more than the size of the United Kingdom.
Sea
ice can reflect as much as 90% of the sunlight back into space. Once
the ice has melted away, however, the water of the ocean reflects
only 6% of the incoming solar radiation and absorbs the rest. This is
depicted in above image as feedback #1.
As
Professor Peter Wadhams once
calculated,
warming due to Arctic snow and ice loss could more than double the
net warming now caused by all emissions by all people of the world.
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Sea
ice acts as a buffer that absorbs heat. When ice is melting, each
gram of ice will take 334 Joule of heat to change into water, while
the temperature remains at 0° Celsius or 32° Fahrenheit.
Once all ice has turned into water, all further heat goes into heating up the water. To raise the temperature of one gram of water by one degree Celsius then takes only 4.18 Joule of heat. In other words, melting of the ice absorbs 8 times as much heat as it takes to warm up the same mass of water from zero to 10°C. This is depicted in above image as feedback #14.
Above video, created by Stuart Trupp, shows how added heat at first (A) goes mainly into warming up water that contains ice cubes. From about 38 seconds into the movie, all heat starts going into the transformation of the ice cubes into water, while the temperature of the water doesn't rise (B). More than a minute later, as the ice cubes have melted (C), the temperature of the water starts rising rapidly again.
Once all ice has turned into water, all further heat goes into heating up the water. To raise the temperature of one gram of water by one degree Celsius then takes only 4.18 Joule of heat. In other words, melting of the ice absorbs 8 times as much heat as it takes to warm up the same mass of water from zero to 10°C. This is depicted in above image as feedback #14.
Above video, created by Stuart Trupp, shows how added heat at first (A) goes mainly into warming up water that contains ice cubes. From about 38 seconds into the movie, all heat starts going into the transformation of the ice cubes into water, while the temperature of the water doesn't rise (B). More than a minute later, as the ice cubes have melted (C), the temperature of the water starts rising rapidly again.
Methane is a further feedback, depicted as feedback #2 on the image further above. As the water of the Arctic Ocean keeps getting warmer, the danger increases that heat will reach the seafloor where it can trigger release of huge amounts of methane, in an additional feedback loop that will make warming in the Arctic accelerate and escalate into runaway warming.
Sediments underneath the Arctic Ocean hold vast amounts of methane. Just one part of the Arctic Ocean alone, the East Siberian Arctic Shelf (ESAS, see map below), holds up to 1700 Gt of methane. A sudden release of just 3% of this amount could add over 50 Gt of methane to the atmosphere, and experts consider such an amount to be ready for release at any time.
Total
methane burden in the atmosphere now is 5 Gt. The 3 Gt that has been
added since the 1750s is responsible for almost half of all global
warming.
The
amount of carbon stored in hydrates globally was in 1992 estimated to
be 10,000 Gt (USGS), while a more recent estimate gives a figure of
63,400 Gt (Klauda & Sandler, 2005). The East Siberian Arctic
Shelf (ESAS) alone holds up to 1700 Gt of methane in the form of
methane hydrates and free gas contained in sediments, of which 50 Gt
is ready for abrupt release at any time.
The
situation is dire a calls for comprehensive and effective action as
described in the Climate Plan.
Links
- Feedbacks in the Arctichttp://arctic-news.blogspot.com/p/feedbacks.html
- Albedo changes in the Arctic http://arctic-news.blogspot.com/2012/07/albedo-change-in-arctic.html
- The time has come to spread the messagehttp://arctic-news.blogspot.com/2013/12/the-time-has-come-to-spread-the-message.html
- Greenhouse gas levels and temperatures keep risinghttp://arctic-news.blogspot.com/2016/01/greenhouse-gas-levels-and-temperatures-keep-rising.html
- Feedbacks in the Arctichttp://arctic-news.blogspot.com/p/feedbacks.html
- Albedo changes in the Arctic http://arctic-news.blogspot.com/2012/07/albedo-change-in-arctic.html
- The time has come to spread the messagehttp://arctic-news.blogspot.com/2013/12/the-time-has-come-to-spread-the-message.html
- Greenhouse gas levels and temperatures keep risinghttp://arctic-news.blogspot.com/2016/01/greenhouse-gas-levels-and-temperatures-keep-rising.html
-
Arctic sea ice area at record low for time of
year
-
Climate Planhttp://arctic-news.blogspot.com/p/plan.html
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