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| [ image from JAXA ] |
Not only is Arctic sea ice extent at record low for time of year, the sea ice is also rapidly getting thinner, more fractured, lower in concentration and darker in color.
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| [ Cracks in sea ice north of Greenland on June 19, 2016, created with Arctic-io image ] |
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| [ click on images to enlarge ] |
the Arctic Ocean (and thus warms up the Arctic Ocean there).
On June 20, 2016, the Sun will reach its highest point (Solstice), and the Arctic will have 24 hours sunlight, i.e. on the Arctic Circle (latitude 66.56° north) or higher. The Arctic is about 20,000,000 square km (7,700,000 square miles) in size and covers roughly 4% of Earth's surface. Insolation during the months June and July is higher in the Arctic than anywhere else on Earth, as illustrated by the image below, by Pidwirny (2006).
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| [ click on images to enlarge ] |
Plenty of meltwater has run off from Greenland in 2016, as illustrated by the NSIDC.gov image on the right. The run-off from Alaska and Siberia into the Pacific seems less by comparison than the run-off into the North Atlantic. So, how could it be that the cold area in the North Pacific has grown larger than the cold area in the North Atlantic?
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| [ click on images to enlarge ] |
Could there be another factor influencing the size of these cold areas in the North Atlantic and the North Pacific?
The image below, created with NOAA images, gives a comparison between the situation on June 1, 2015 (top), and June 1, 2016 (bottom), showing anomalies from 1961-1990.
The difference is striking, especially when considering the strength of the colder anomalies (from 1961-1990). Besides meltwater, something else must be influencing the size and strength of these anomalies in the North Atlantic and the North Pacific in different ways. Quite likely, the difference is caused by the Global Ocean Conveyor Belt (or thermohaline circulation), which is carrying warm water into the North Atlantic, while carrying cold water out of the North Atlantic. In the North Pacific, it is doing the opposite, i.e. carrying cold water in, while carrying warm water out of the North Pacific.
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| [ Note that this animation is a 2.3 MB file that make take some time to fully load ] |
If such trends continue or even strengthen, ever warmer water will be carried from the North Atlantic into the Arctic Ocean, overwhelming possible cooling due to meltwater run-off. Since the Atlantic inflow is about 10 times greater in volume than the Pacific inflow, the net result will be further speeding up of the warming of the Arctic Ocean.
A warmer Arctic Ocean will speed up decline of the sea ice, causing more sunlight to be absorbed by the Arctic Ocean, as one of the feedbacks that are further accelerating warming of the Arctic Ocean. Feedback #14 refers to (latent) heat that previously went into melting. With the demise of the sea ice, an increasing proportion of the ocean heat gets absorbed by the Arctic Ocean.
Once all ice has turned into water, all subsequent heat goes into heating up the water, at 4.18 J/g for every degree Celsius that the temperature of water rises.
The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C.
The sea ice is in a bad shape, as also illustrated by the above concentration comparison, between June 24, 2012, and a forecast for June 24, 2016.
As above comparison shows, the sea ice is now also much thinner than it was in 2012. Thick sea ice used to extend meters below the sea surface in the Arctic, where it could consume massive amounts of ocean heat through melting this ice into water. As such, thick sea ice acted as a buffer. Over the years, Arctic sea ice thickness has declined most dramatically. This means that the buffer that used to consume massive amounts of ocean heat carried by sea currents into the Arctic Ocean, has now largely gone.
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| Latent heat loss, feedback #14 on the Feedbacks page |
The situation is dire and calls for comprehensive and effective action as described at the Climate Plan.
Links
- NASA Study Finds Atlantic 'Conveyor Belt' Not Slowing (March 25, 2010)
jpl.nasa.gov/news/news.php?release=2010-101
- Arctic Ocean Circulation: Going Around At the Top Of the World, by Rebecca Woodgate (2013)
nature.com/scitable/knowledge/library/arctic-ocean-circulation-going-around-at-the-102811553
- Pidwirny, M. (2006). "Earth-Sun Relationships and Insolation". Fundamentals of Physical Geography, 2nd Edition.
physicalgeography.net/fundamentals/6i.html
- Feedbacks
Arctic-news.blogspot.com/p/feedbacks.html
- Climate Plan
Arctic-news.blogspot.com/p/climateplan.html
