Reposted from CLIMATE PROGRESS (http://thinkprogress NULL.org/climate/2012/08/26/745571/why-the-arctic-sea-ice-death-spiral-matters/)
(http://thinkprogress NULL.org/wp-content/uploads/2012/08/Sea_Ice_Extent_L NULL.gif)
Arctic sea ice extent takes a nosedive this year. What does it mean for us? (Source: Japan Aerospace Exploration Agency (http://www NULL.ijis NULL.iarc NULL.uaf NULL.edu/en/home/seaice_extent NULL.htm))
By Neven Acropolis with Kevin McKinney
In the past week the Arctic sea ice cover reached an all-time low (http://neven1 NULL.typepad NULL.com/blog/records/), several weeks before previous records, several weeks before the end of the melting season. The long-term decline of Arctic sea ice has been incredibly fast, and at this point a sudden reversal of events doesn’t seem likely. The question no longer seems to be “will we see an ice-free Arctic?” but “how soon will we see it?”. By running the Arctic Sea Ice blog (http://neven1 NULL.typepad NULL.com/blog/) for the past three years I’ve learned much about the importance of Arctic sea ice. With the help of Kevin McKinney (http://doc-snow NULL.hubpages NULL.com/) I’ve written the piece below, which is a summary of all the potential consequences of disappearing Arctic sea ice.
Arctic sea ice became a recurrent feature on planet Earth around 47 million years (http://bprc NULL.osu NULL.edu/geo/publications/polyak_etal_seaice_QSR_10 NULL.pdf) ago. Since the start of the current ice age, about 2.5 million years ago, the Arctic Ocean (http://en NULL.wikipedia NULL.org/wiki/Arctic_Ocean) has been completely covered with sea ice. Only during interglacials, like the one we are in now, does some of the sea ice melt during summer, when the top of the planet is oriented a bit more towards the Sun and receives large amounts of sunlight for several summer months (http://en NULL.wikipedia NULL.org/wiki/Midnight_sun). Even then, when winter starts, the ice-free portion of the Arctic Ocean freezes over again with a new layer of sea ice.
Since the dawn of human civilization, 5000 to 8000 years ago, this annual ebb and flow of melting and freezing Arctic sea ice has been more or less consistent. There were periods when more ice melted during summer, and periods when less melted. However, a radical shift (http://www NULL.skepticalscience NULL.com/Arctic-sea-ice-hockey-stick-melt-unprecedented-in-last-1450-years NULL.html) has occurred in recent times. Ever since satellites allowed a detailed view of the Arctic and its ice, a pronounced decrease in summer sea ice cover has been observed (with this year setting a new record low). When the IPCC released its Fourth Assessment Report in 2007, it was generally thought (http://www NULL.ipcc NULL.ch/publications_and_data/ar4/wg2/en/figure-15-3 NULL.html) that the Arctic could become ice-free somewhere near the end of this century. But changes in the Arctic have progressed at such speed that most experts now think 2030 might see an ice-free Arctic for the first time. Some say it could even happen this decade.
(http://thinkprogress NULL.org/wp-content/uploads/2012/08/2-albedofeedback NULL.jpg)What makes this event significant, is the role Arctic sea ice plays as a reflector of solar energy. Ice is white and therefore reflects a large part of incoming sunlight back out to space. But where there is no ice, dark ocean water absorbs most of the sunlight and thus heats up. The less ice there is, the more the water heats up, melting more ice. This feedback (http://en NULL.wikipedia NULL.org/wiki/Ice-albedo_feedback) has all kinds of consequences for the Arctic region. Disappearing ice can be good for species such as tiny algae that profit (http://news NULL.stanford NULL.edu/news/2012/june/arctic-algal-blooms-060712 NULL.html) from the warmer waters and extended growing season, but no sea ice could spell catastrophe for larger animals (http://www NULL.livescience NULL.com/15560-walrus-haul-sea-ice NULL.html) that hunt or give birth to offspring on the ice. Rapidly changing conditions also have repercussions for human populations whose income and culture depend on sea ice. Their communities literally melt and wash away (http://www NULL.adn NULL.com/2012/08/07/2577036/arctic-villages-hit-hard-by-climate NULL.html) as the sea ice no longer acts as a buffer to weaken wave action.
(http://thinkprogress NULL.org/wp-content/uploads/2012/08/3-jetstream NULL.jpg)But what happens in the Arctic, doesn’t stay in the Arctic. The rapid disappearance of sea ice cover can have consequences that are felt all over the Northern Hemisphere, due to the effects (http://e360 NULL.yale NULL.edu/feature/linking_weird_weather_to_rapid_warming_of_the_arctic/2501/) it has on atmospheric patterns. As the ice pack becomes smaller ever earlier into the melting season, more and more sunlight gets soaked up by dark ocean waters, effectively warming up the ocean. The heat and moisture that are then released to the atmosphere in fall and winter could be leading to disturbances of the jet stream (http://en NULL.wikipedia NULL.org/wiki/Jet_stream), the high-altitude wind that separates warm air to its south from cold air to the north. A destabilized jet stream becomes more ‘wavy’, allowing frigid air to plunge farther south, a possible factor in the extreme winters (http://www NULL.noaa NULL.gov/features/02_monitoring/warmarctic NULL.html) that were experienced all around the Northern Hemisphere in recent years. Another side-effect is that as the jet stream waves become larger, they slow down or even stall at times, leading to a significant increase in so-called blocking events. These cause extreme weather simply because they lead to unusually prolonged conditions of one type or another. The recent prolonged heatwave (http://en NULL.wikipedia NULL.org/wiki/Summer_2012_North_American_heat_wave), drought and wildfires in the USA are one example of what can happen; another is the cool, dull and extremely wet first half of summer 2012 in the UK and other parts of Eurasia.
[JR: See Arctic Death Spiral: How It Favors Extreme, Prolonged Weather Events ‘Such As Drought, Flooding, Cold Spells And Heat Waves’ (http://thinkprogress NULL.org/climate/2012/08/22/727501/arctic-death-spiral-how-it-favors-extreme-prolonged-weather-events-such-as-drought-flooding-cold-spells-and-heat-waves/).]
The accumulation of heat in Arctic waters also influences other frozen parts of the Arctic, such as glaciers and ice caps on Greenland (http://www NULL.skepticalscience NULL.com/Variations_in_Greenland_Glaciers NULL.html) and in the Canadian Archipelago (http://www NULL.nature NULL.com/nature/journal/v473/n7347/full/nature10089 NULL.html). As there is less and less sea ice to act as a buffer, more energy can go into melting glaciers from below and warming the air above them. This has a marked effect on Greenland’s marine-terminating glaciers and the Greenland Ice Sheet. Not only are glaciers flowing faster (http://www NULL.csmonitor NULL.com/Science/2012/0503/Greenland-s-glaciers-melting-faster-say-scientists) towards sea, but there is also a rapid increase in the summer surface melt (http://neven1 NULL.typepad NULL.com/blog/2012/07/unprecedented-greenland-ice-sheet-surface-melt- NULL.html) Greenland experiences, leading to accelerating mass loss (http://www NULL.skepticalscience NULL.com/Greenland-ice-loss-continues-to-accelerate NULL.html) from the Greenland Ice Sheet. As the Arctic warms, an increased contribution to sea level rise is inevitable.
(http://thinkprogress NULL.org/wp-content/uploads/2012/08/5-permafrostdistribution NULL.jpg)Another way Arctic warming could have worldwide consequences is through its influence on permafrost. Permanently frozen soils worldwide contain 1400-1700 Gigatons of carbon, about four times more than all the carbon emitted by human activity in modern times. A 2008 study (http://nsidc NULL.org/news/press/20080610_Slater NULL.html) found that a period of abrupt sea-ice loss could lead to rapid soil thaw, as far as 900 miles inland. Apart from widespread damage (http://www NULL.cbc NULL.ca/news/canada/story/2011/11/16/north-big-fix-permafrost NULL.html) to infrastructure (roads, houses) in northern territories, resulting annual carbon emissions could eventually amount to 15-35 percent (http://www NULL.nytimes NULL.com/2011/12/17/science/earth/warming-arctic-permafrost-fuels-climate-change-worries NULL.html?_r=1) of today’s yearly emissions from human activities, making the reduction of greenhouse gases in the atmosphere a much more difficult task.
(http://thinkprogress NULL.org/wp-content/uploads/2012/08/6-methaneconcentration NULL.png)An even more worrying potential source of greenhouse gases is the methane in the seabed of the Arctic Ocean, notably off the coast of Siberia. These so-called clathrates (http://en NULL.wikipedia NULL.org/wiki/Clathrate_gun_hypothesis) contain an estimated 1400 Gigatons of methane, a more potent though shorter-lived greenhouse gas than carbon dioxide. Methane clathrate, a form of water ice that contains a large amount of methane within its crystal structure, remains stable under a combination of high pressure and low temperature. At a depth of 50 meters or less the East Siberian Arctic Shelf (http://en NULL.wikipedia NULL.org/wiki/Siberian_Shelf) contains the shallowest methane clathrate deposits, and is thus most vulnerable (http://www NULL.skepticalscience NULL.com/arctic-methane-outgassing-e-siberian-shelf-part1 NULL.html) to rising water temperatures. Current methane concentrations in the Arctic already average about 1.90 parts per million, the highest in 400,000 years.
(http://thinkprogress NULL.org/wp-content/uploads/2012/08/7-russiaplantsflag NULL.jpg)Apart from these unrecoverable sources of fossil fuel the Arctic is also endowed with large amounts of recoverable oil and natural gas. As the sea ice retreats, the Arctic’s fossil treasures are eyed greedily (http://business NULL.financialpost NULL.com/2012/07/27/arctic-the-great-sled-race/) by large corporations and nations bordering the Arctic Ocean. Not only might this lead to geopolitical tensions (http://www NULL.thestarphoenix NULL.com/technology/Climate+change+could+chill+international+relations+Arctic/6761661/story NULL.html) in a world where energy is rapidly becoming more expensive, it is also highly ironic that the most likely cause of the disappearance of Arctic sea ice – the extraction and burning of fossil fuels – could lead to more extraction of said fuels. Another feedback loop.
News articles referring to the Arctic and its sea ice usually have pictures of polar bears accompanying the text. But although many animals in the Arctic will be impacted negatively by the vanishing of Arctic sea ice, much more is at stake. After thousands of years in which the sea ice played a vital role in the relatively stable conditions under which modern civilization, agriculture and a 7 billion strong world population could develop, it increasingly looks as if warming caused by the emission of greenhouse gases is bringing an end to these stable conditions. Whether there still is time to save the Arctic sea ice, is difficult to tell, but consequences will not disappear when the ice is gone. It seems these can only be mitigated by keeping fossil fuels in the ground and out of the air. Whichever way you look at it, business-as-usual is not an option.
For more information on Arctic sea ice, check out the Arctic Sea Ice blog (http://neven1 NULL.typepad NULL.com/blog).
– Neven Acropolis with Kevin McKinney
Arctic sea ice extent reconstruction – Kinnard et al. 2011 (http://www NULL.nature NULL.com/nature/journal/v479/n7374/full/nature10581 NULL.html)
Sea ice albedo feedback – NASA (http://www NULL.nasa NULL.gov/topics/earth/features/sea_ice_min NULL.html)
Polar jet stream – NC State University (http://www NULL.nc-climate NULL.ncsu NULL.edu/edu/k12/ NULL.JetStreams)
Greenland ice sheet surface melt – NASA (http://www NULL.nasa NULL.gov/topics/earth/features/greenland-melt NULL.html)
Permafrost distribution in the Arctic – GRID-Arendal (http://www NULL.grida NULL.no/graphicslib/detail/permafrost-distribution-in-the-arctic_3823)
Atmospheric methane concentration – NOAA ESRL (http://www NULL.esrl NULL.noaa NULL.gov/gmd/ccgg/iadv/)
Russia plants flag at North Pole – Reuters (http://www NULL.reuters NULL.com/article/2007/09/20/us-russia-arctic-idUSL2082113920070920)