Arctic sea ice minimum extent typically occurs about half September. In 2012, minimum extent was reached on September 17, 2012, when extent was 3.387 million km².
On July 28, 2019, Arctic sea ice extent was 6.576 million km². How much extent do you think there will be by September 17, 2019? From July 28, 2019, to September 17, 2019, that's a period of 52 days during which a lot of melting can occur. Could there be a Blue Ocean Event in 2019, with virtually all sea ice disappearing in the Arctic?
Consider this. Extent was 6.926 million km² on September 17, 1989. Extent was 3.387 million km² on September 17, 2012, so 3.539 million km² had disappeared in 23 years. Over those years, more ice extent disappeared than what was left on September 17, 2012.
The question is how much sea ice extent will be left when it will reach its minimum this year, i.e. in September 2019. The red dashed line on the image at the top continues the path of the recent fall in sea ice extent, pointing at zero Arctic sea ice extent in September 2019. Progress is followed at this post.
Zero Arctic sea ice in 2019
Zero Arctic sea ice in 2019 sounds alarming, and there is good reason to be alarmed.
Above map shows temperatures on Greenland on July 31, 2019, with temperatures at one location as high as 23.2°C or 73.8°F and at another location - in the north - as high as 14.2°C or 57.6°F.The map on the right shows sea surface temperature anomalies compared to 1961-1990 as on July 29, 2019. Note the high anomalies in the areas where the sea ice did disappear during the past few months. The reason for these high anomalies is that the buffer has disappeared that previously had kept consuming heat in the process of melting.
Where that buffer is gone, the heat has to go somewhere else, so it will be absorbed by the water and it will also speed up heating of the atmosphere over the Arctic.
Sea ice melting is accelerating for a number of reasons:
- Ocean Heat - Much of the melting of the sea ice occurs from below and is caused by heat arriving in the Arctic Ocean from the Atlantic Ocean and the Pacific Ocean.
- Direct Sunlight - Hot air will melt the ice from above and this kind of melting can increase strongly due to changing wind patterns.
- Rivers - Heatwaves over land can extend over the Arctic Ocean and they also heat up river water flowing into the Arctic Ocean.
- Fires - Changing wind patterns can also increase the intensity and duration of such heatwaves that can also come with fires resulting in huge amounts of greenhouse gas emissions, thus further speeding up the temperature rise, and also resulting in huge emissions of soot that, when settling on sea ice, speeds up melting (see images below).
- Numerous feedbacks will further speed up melting. Heating is changing the texture of the sea ice at the top and is making melt pools appear, both of which cause darkening of the surface. Some further feedbacks, i.e. storms and clouds are discussed below in more detail.
Above combination image shows smoke from fires in Siberia getting pushed over the Laptev Sea on August 11, 2019, due to cyclonic winds over the Arctic Ocean. This was also discussed in an earlier post. The image below shows the situation on August 12, 2019.
The image below shows the situation on August 14, 2019.
In the video below, Paul Beckwith discusses the situation.
In the video below, Paul Beckwith discusses the heating impact of albedo loss due to Arctic sea ice loss, including the calculations in a recent paper.
As the Arctic is heating up faster than the rest of the world, it is also more strongly affected by the resulting extreme weather events, such as heatwaves, fires, strong winds, rain and hail storms, and such events can strongly speed up the melting of the sea ice.
All around Greenland, sea ice has now virtually disappeared. This is the more alarming considering that the thickest sea ice was once located north of Greenland. This indicates that the buffer is almost gone.
Why is disappearance of Arctic sea ice so important? Hand in hand with albedo loss as the sea ice disappears, there is loss of the buffer (feedbacks #1, #14 and more). As long as there is sea ice in the water, this sea ice will keep absorbing heat as it melts, so the temperature will not 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.
Once the sea ice is gone, further heat must go elsewhere. This heat will raise the temperature of the water and will also make the atmosphere heat up faster.
Storms and Clouds
Storms: As temperatures in the Arctic are rising faster than at the Equator, the Jet Stream is changing, making it easier for warm air to enter the Arctic and for cold air to descend over continents that can thus become much colder than the oceans, and this stronger temperature difference fuels storms.
Clouds: More evaporation will occur as the sea ice disappears, thus further heating up the atmosphere (technically know as latent heat of vaporization).
In the video below, Paul Beckwith further discusses Arctic albedo change and clouds.
Disappearance of the sea ice causes more clouds to form over the Arctic. This on the one hand makes that more sunlight gets reflected back into space. On the other hand, this also make that less outward infrared radiation can escape into space. The net effect of more clouds is that they are likely cause further heating of the air over the Arctic Ocean (feedbacks #23 and #25).
More low-altitude clouds will reflect more sunlight back into space, and this occurs most during Summer when there is most sunshine over the Arctic. The image below, a forecast for August 17, 2019, shows rain over the Arctic. Indeed, more clouds in Summer can also mean rain, which can devastate sea ice, as discussed in an earlier post.
Regarding less outward radiation, the IPCC has long warned, e.g. in TAR, about a reduction in outgoing longwave radiation (OLR): "An increase in water vapour reduces the OLR only if it occurs at an altitude where the temperature is lower than the ground temperature, and the impact grows sharply as the temperature difference increases."
While reduction in OLR due to water vapor is occurring all year long, the impact is particularly felt in the Arctic in Winter when the air is much colder than the surface. In other words, less OLR makes Arctic sea ice thinner, especially in Winter.
The inflow of ocean heat into the Arctic Ocean can increase strongly as winds increase in intensity. Storms can push huge amounts of hot, salty water into the Arctic Ocean, as discussed earlier, such as in this post and this post. As also described at the extreme weather page, stronger storms in Winter will push more ocean heat from the Atlantic toward the Arctic Ocean, further contributing to Arctic sea ice thinning in Winter.
Seafloor Methane
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| [ The Buffer has gone, feedbacks #14 and #16 ] |
As the buffer disappears that until now has consumed huge amounts of heat, the temperature of the water of the Arctic Ocean will rise even more rapidly, with the danger that further heat will reach methane hydrates at the seafloor of the Arctic Ocean, causing them to get destabilized and release huge amounts of methane (feedback #16).
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| [ from an earlier post ] |
As the image on the right shows, mean global levels of methane (CH₄) have risen much faster than carbon dioxide (CO₂) and nitrous oxide (N₂O), in 2017 reaching, respectively, 257%, 146% and 122% their 1750 levels.
Temperature Rise
Huge releases of seafloor methane alone could make marine stratus clouds disappear, as described in an earlier post, and this clouds feedback could cause a further 8°C global temperature rise.
Indeed, a rapid temperature rise of as much as 18°C could result by the year 2026 due to a combination of elements, including albedo changes, loss of sulfate cooling, and methane released from destabilizing hydrates contained in sediments at the seafloor of oceans.
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| [ from an earlier post ] |
Below is Malcolm Light's updated Extinction Diagram.
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| [ click on images to enlarge ] |
Link
• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html
• Smoke Covers Much Of Siberia
https://arctic-news.blogspot.com/2019/07/smoke-covers-much-of-siberia.html
• Extreme Weather
https://arctic-news.blogspot.com/p/extreme-weather.html
• Albedo and more
https://arctic-news.blogspot.com/p/albedo.html
• Radiative Heating of an Ice‐Free Arctic Ocean, by Kristina Pistone et al. (2019)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082914
• High cloud coverage over melted areas dominates the impact of clouds on the albedo feedback in the Arctic, by Min He et al. (2019)
https://www.nature.com/articles/s41598-019-44155-w
• ESD Reviews: Climate feedbacks in the Earth system and prospects for their evaluation, by Christoph Heinze et al. (2019)
https://www.earth-syst-dynam.net/10/379/2019/esd-10-379-2019-discussion.html
• Contribution of sea ice albedo and insulation effects to Arctic amplification in the EC-Earth Pliocene simulation, by Jianqiu Zheng et al. (2019)
https://www.clim-past.net/15/291/2019
• Far-infrared surface emissivity and climate, by Daniel Feldman et al. (2014)
https://www.pnas.org/content/111/46/16297.abstract
• Extreme Weather
https://arctic-news.blogspot.com/p/extreme-weather.html
• Feedbacks in the Arctic
https://arctic-news.blogspot.com/p/feedbacks.html
• Rain Storms Devastate Arctic Ice And Glaciers
https://arctic-news.blogspot.com/2015/01/rain-storms-devastate-arctic-ice-and-glaciers.html
• A rise of 18°C or 32.4°F by 2026?
https://arctic-news.blogspot.com/2019/02/a-rise-of-18c-or-324f-by-2026.html
• As El Niño sets in, will global biodiversity collapse in 2019?
https://arctic-news.blogspot.com/2018/11/as-el-nino-sets-in-will-global-biodiversity-collapse-in-2019.html
• Dangerous situation in Arctic
https://arctic-news.blogspot.com/2018/11/dangerous-situation-in-arctic.html
• Warning of mass extinction of species, including humans, within one decade
https://arctic-news.blogspot.com/2017/02/warning-of-mass-extinction-of-species-including-humans-within-one-decade.html