Arctic sea ice decline: Difference between revisions
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=== Wildlife === |
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Polar bears are turning to alternate food sources, because Arctic sea ice melts earlier and freezes later each year. Polar bears have less time to hunt their historically preferred prey seal pups and must spend more time on land, and hunt other animals.<ref>{{cite journal |
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| author = Elizabeth Peacock, Mitchell K. Taylor, Jeffrey Laake and Ian Stirling |
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| title = Population ecology of polar bears in Davis Strait, Canada and Greenland |
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| journal = The Journal of Wildlife Management |
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| volume = 77 |
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| doi = 10.1002/jwmg.489 |
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}}</ref> As a result the diet is less nutritional which lead to reduced body size and reproduction, thus indicators of population decline in polar bears.<ref>{{cite journal |
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| author = Karyn D. Rode, Steven C. Amstrup, and Eric V. Regehr |
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| title = Reduced body size and cub recruitment in polar bears associated with sea ice decline |
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| journal = Ecological Applications |
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| volume = 20 |
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| pages = 768–782 |
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| doi = 10.1890/08-1036.1 |
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| url = http://www.esajournals.org/doi/abs/10.1890/08-1036.1 |
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Revision as of 10:33, 26 January 2014
Arctic sea ice decline describes the sea ice loss observed in recent decades in the Arctic. The IPCC AR5 report concluded with high confidence that sea ice continues to decrease in extent and there is robust evidence for the downward trend in Arctic summer sea ice extent since 1979.[1]
Observation
Observation with satellites show that sea ice declines since a few decades in area, extent, and volume and may cease to exist during the summer month sometime during the 21st century. Sea ice extent is the area with at least 15% sea ice, while the volume is the total amount of sea ice.[2]
Ice-free summer?
An "ice-free" Arctic Ocean is often defined as "having less than 1 million square kilometers of sea ice", because it is very difficult to melt the thick ice around the Canadian Arctic Archipelago;[3][4][5] the IPCC AR5 defines "nearly ice-free conditions" as "when sea ice extent is less than 106 km2 for at least five consecutive years" and (for at least one scenario) estimates that this might occur around 2050.[1]
Many scientists have attempted to estimate when the Arctic will be "ice-free". In doing so, they have noted that climate model predictions have tended to be overly conservative regarding sea ice decline.[6][7] Wang and Overland, in 2009, predicted that there would be an ice-free Arctic in the summer by 2037.[8] Similarly, a 2006 paper by Marika Holland et al. predicted "near ice-free September conditions by 2040,"[9] and Boé et al. found that the Arctic will probably be ice-free in September before the end of the 21st century.[10]
Implications
Implications which arise from lesser ocean surface covered with sea-ice include the ice-albedo feedback or warmer sea surface temperatures which increase ocean heat content, which in turn changes evaporation patterns and the polar vortex.
Atmospheric chemistry
Melting of sea ice releases molecular chlorine, which reacts with sunlight to produce chlorine atoms. Because chlorine atoms are highly reactive, they can expedite the degradation of methane and tropospheric ozone and the oxidation of mercury to more toxic forms.[11] Cracks in sea ice are causing ozone and mercury uptake in the surrounding environment.[12]
Wildlife
Polar bears are turning to alternate food sources, because Arctic sea ice melts earlier and freezes later each year. Polar bears have less time to hunt their historically preferred prey seal pups and must spend more time on land, and hunt other animals.[13] As a result the diet is less nutritional which lead to reduced body size and reproduction, thus indicators of population decline in polar bears.[14]
See also
References
- ^ a b IPCC AR5 WG1 (2013). PDF "Summary for policymakers".
{{cite journal}}: Check|url=value (help); Cite journal requires|journal=(help)CS1 maint: numeric names: authors list (link) - ^ "Daily Updated Time series of Arctic sea ice area and extent derived from SSMI data provided by NERSC". Retrieved 14 September 2013.
- ^ http://www.pnas.org/content/early/2013/07/10/1219716110.abstract
- ^ http://phys.org/news/2013-08-ice-free-arctic-2050s.html#inlRlv
- ^ http://www.atmos.pku.edu.cn/yhu/pnas-liu-2013.pdf
- ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1002/grl.50316, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1002/grl.50316instead. - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1029/2007GL029703, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1029/2007GL029703instead. - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1029/2009GL037820, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1029/2009GL037820instead. - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1029/2006GL028024, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1029/2006GL028024instead. - ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/ngeo467, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1038/ngeo467instead. - ^ Jin Liao et al.(2013) (2014). "High levels of molecular chlorine in the Arctic atmosphere". Nature Geoscience Letter. doi:10.1038/ngeo2046. Retrieved January 14, 2014.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: numeric names: authors list (link) - ^ Christopher W. Moore, Daniel Obrist, Alexandra Steffen, Ralf M. Staebler, Thomas A. Douglas, Andreas Richter & Son V. Nghiem (2014). "Convective forcing of mercury and ozone in the Arctic boundary layer induced by leads in sea ice". Nature Letter. doi:10.1038/nature12924. Retrieved January 16, 2014.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Elizabeth Peacock, Mitchell K. Taylor, Jeffrey Laake and Ian Stirling (2013). "Population ecology of polar bears in Davis Strait, Canada and Greenland". The Journal of Wildlife Management. 77 (3): 463–476. doi:10.1002/jwmg.489. Retrieved January 26, 2014.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Karyn D. Rode, Steven C. Amstrup, and Eric V. Regehr (2010). "Reduced body size and cub recruitment in polar bears associated with sea ice decline". Ecological Applications. 20: 768–782. doi:10.1890/08-1036.1. Retrieved January 26, 2014.
{{cite journal}}: Cite has empty unknown parameter:|month=(help)CS1 maint: multiple names: authors list (link)
