Friday, July 13, 2018

Disappearance of Arctic Sea Ice

The image on the right shows sea surface temperatures on July 6 for the years 2014 to 2018 at a location near Svalbard (at 77.958°N, 5.545°E), with an exponential trend added based on the data.

The combination image below shows sea surface temperatures on July 6 for each of these years, with the location highlighted by a green circle:
2014:  -0.8°C or 30.6°F
2015:   6.2°C or 43.2°F
2016:   8.3°C or 47.0°F
2017: 14.4°C or 57.9°F
2018: 16.6°C or 61.9°F

The situation reflects the rapid decline of Arctic sea ice over the years and constitutes a stark warning of imminent sea ice collapse and its consequences for the world at large.

[ click on images to enlarge ]
The image on the right shows the sea surface temperature on July 14, 2018, at that location. It was as warm as 17.1°C or 62.7°F near Svalbard.

This compares to a sea surface temperature of 5°C or 40.9°F in 1981-2011 at that location (at the green circle).

The images illustrate why sea ice has fallen dramatically in volume, especially so where sea currents push warm water from the Atlantic Ocean underneath the sea ice.

The decline of Arctic sea ice volume over the years is illustrated by the graph below by Jim Pettit.

As the Wipneus image below shows, Arctic sea ice volume on July 10, 2018, was at a record low for the time of the year.


The animation on the right shows a fall in volume of some 1 meter over most of the sea ice, over the period from June 21 through July 12, 2018, with a further eight days of forecasts added.

The animation illustrates the huge amount of melting taking place from underneath, due to an inflow of heat from the Atlantic Ocean and the Pacific Ocean, and from warm water from rivers that end in the Arctic Ocean. Meanwhile, sea ice extent doesn't fall very much at all.

When only looking at sea ice extent, the dramatic fall in sea ice volume may be overlooked.

Complete disappearance of Arctic sea ice in September 2018 is within the margins of a trend based on yearly annual minimum volume, as illustrated by the image on the right.

Latent heat can make such disappearance come abruptly and - for people who only look at changes in extent - rather unexpectedly.

Latent heat is energy associated with a phase change, such as the energy absorbed by solid ice when it changes into water (melting). During a phase change, the temperature remains constant.

Sea ice acts as a buffer that absorbs heat, while keeping the temperature at zero degrees Celsius. As long as there is sea ice in the water, this sea ice will keep absorbing heat, so the temperature doesn't rise at the sea surface.

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.


Oceans take up over 90% of global warming, as illustrated by the image below. Ocean currents make that huge amounts of this heat keep entering the Arctic Ocean from the Pacific Ocean and the Atlantic Ocean.


Once the sea ice is gone, further ocean heat must go elsewhere, i.e. it will typically raise the temperature of the water. The atmosphere will also warm up faster. More evaporation will also occur once the sea ice is gone, which will cool the sea surface and warm up the atmosphere (technically know as latent heat of vaporization).

As temperatures in the Arctic are rising faster than at the Equator, the Jet Stream will change, making it easier for warm air to enter the Arctic. More clouds will form over the Arctic, which will reflect more sunlight into space, but which will also make that less outward IR radiation can escape into space over the Arctic, with a net warming effect.

Meanwhile, El Niño is getting stronger, as illustrated by above image on the right. A warmer Arctic comes with stronger heat waves, forest fires and associated emissions, and rapid warming of water in rivers that end in the Arctic Ocean, all of which will further warm up the Arctic Ocean. Forest fires have already been burning strongly in Siberia over the past few months and methane recently reached levels as high as 2817 ppb (on July 8, 2018, pm).

One huge danger is that, as the buffer disappears that until now has consumed huge amounts of ocean heat, and the Arctic Ocean keeps warming, further heat will reach methane hydrates at the seafloor of the Arctic Ocean, causing them to get destabilized and release methane.

[ The Buffer has gone, feedback #14 on the Feedbacks page ]
Additionally, disappearance of the sea ice will come with albedo changes that mean that a lot more sunlight will be absorbed, instead of getting reflected back into space as occurred previously.


Similar albedo changes are likely to take place over land in the Arctic soon thereafter. Adding up all warming elements associated with disappearance of the sea ice can result in an additional global warming of several degrees Celsius.

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

Links

• Can we weather the Danger Zone?
https://arctic-news.blogspot.com/2018/07/can-we-weather-the-danger-zone.html

• How much warmer is it now?
https://arctic-news.blogspot.com/2018/04/how-much-warmer-is-it-now.html

• Feedbacks
https://arctic-news.blogspot.com/p/feedbacks.html

• Latent Heat
https://arctic-news.blogspot.com/p/latent-heat.html

• How much warming have humans caused?
https://arctic-news.blogspot.com/2016/05/how-much-warming-have-humans-caused.html

• The Threat
https://arctic-news.blogspot.com/p/threat.html

• Extinction
https://arctic-news.blogspot.com/p/extinction.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html



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