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1) Hvis isen smelter pga mere co2, som virker ved at opvarme atmosfæren over isen, så bør vi se en vis temperaturstigning i samme, så der kan overføres mere energi fra atmosfæren til isen.
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Vh Troels
Nej, Troels
Det kan man ikke regne med.
Luftens varme går til at smelte is - og sålænge der er is, er temperaturen ca.0°C lige over isen.
Bemærk at der med relativt varm rolig luft over isen, vil være inversion over isen (temperaturen stiger med højden).
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Dog:
2009, Large-scale atmospheric circulation changes are associated with the recent loss of Arctic sea ice.
By JAMES E. OVERLAND1∗ and MUYIN WANG2, 1NOAA/Pacific Marine Environmental Laboratory, Seattle, WA 98115, USA; 2JISAO/University of Washington, Seattle, WA 98195, USA:
http://www.webpages.uidaho.edu....pdf
Citat: "...
The most important conclusion of this and several recent papers is that the loss of summer Arctic sea ice can have an impact on the larger Northern Hemisphere atmospheric circulation. We show increased air temperatures in the lower troposphere over the Arctic in late autumn (OND), similar to the analysis of Serreze et al. (2009) for (SON), and thus a delayed north–south gradient in the 1000–500 hPa thickness field associated with a reduction in September sea ice cover.
This connection is mediated by heat storage in the ocean (Fig. 5) and an erosion of the stable Arctic boundary layer from the surface (Schweiger et al., 2008).
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A combination of modest anthropogenic forcing and the recent presence of the positive AO and negative AD, acting through the loss of summer sea ice and increased autumn temperatures, have induced further changes in the atmospheric circulation at an earlier date than anticipated from anthropogenic contributions alone.
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However, as summer Arctic open water area increases over the next decades, we anticipate an increasing influence of loss of summer sea ice on the atmospheric northern hemisphere general circulation in following seasons.
Thus, while the magnitude of the direct effect of anthropogenic forcing to climate change is still emerging, it may already have shifted the normal chaotic patterns of natural climate variability in the sub-Arctic through sea ice/ocean feedbacks and contributed to an accelerated arctic amplification of temperature.
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Abstract:
2011, Influence of winter and summer surface wind anomalies on Summer Arctic sea ice extent
Masayo Ogi; Koji Yamazaki; John Wallace
Japan Agency for Marine-Earth Science and Technology, Japan
http://conference2011.wcrp-cli....pdf
Citat: "...
Most climate models have underestimated the observed decline of Arctic SIE: the observed 2007 minimum was much lower than simulated in any of the models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4). The causes of the rapid decline in SIE remain uncertain.
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Based on a statistical analysis incorporating 925-hPa wind fields from the NCEP/NCAR Reanalyses, it is shown that the combined effect of winter and summer wind forcing accounts for 50% of the variance of the change in September Arctic sea ice extent from one year to the next (ƒSIE) and it also explains roughly 1/3 of the downward linear trend of SIE over the past 31 years.
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22 March 2010, Wind contributing to Arctic sea ice loss, study finds.
New research does not question climate change is also melting ice in the Arctic, but finds wind patterns explain steep decline:
http://www.guardian.co.uk/envi...ctic
Citat: "...
Much of the record breaking loss of ice in the Arctic ocean in recent years is down to the region's swirling winds and is not a direct result of global warming, a new study reveals.
Ice blown out of the region by Arctic winds can explain around one-third of the steep downward trend in sea ice extent in the region since 1979, the scientists say.
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About half of the variation in maximum ice loss each September is down to changes in wind patterns, the study says.
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A number of other factors were also responsible for ice loss, including warming of the air and ocean, she added.
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Atmospheric circulation: Polar cell:
http://en.wikipedia.org/wiki/A...cell
Citat: "...
The wind belts girdling the planet are organised into three cells: the Hadley cell, the Ferrel cell, and the Polar cell. Contrary to the impression given in the simplified diagram, the vast bulk of the vertical motion occurs in the Hadley cell; the explanations of the other two cells are complex.
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http://en.wikipedia.org/wiki/A...cell
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The Polar cell is likewise a simple system. Though cool and dry relative to equatorial air, air masses at the 60th parallel are still sufficiently warm and moist to undergo convection and drive a thermal loop.
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When the air reaches the polar areas, it has cooled considerably, and descends as a cold, dry high pressure area, moving away from the pole along the surface but twisting westward as a result of the Coriolis effect to produce the Polar easterlies.
The outflow from the cell creates harmonic waves in the atmosphere known as Rossby waves. These ultra-long waves play an important role in determining the path of the jet stream, which travels within the transitional zone between the tropopause and the Ferrel cell. By acting as a heat sink, the Polar cell also balances the Hadley cell in the Earth’s energy equation.
It can be argued that the Polar cell is the primary weathermaker for regions above the middle northern latitudes.
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The Hadley cell and the Polar cell are similar in that they are thermally direct; in other words, they exist as a direct consequence of surface temperatures; their thermal characteristics override the effects of weather in their domain. The sheer volume of energy the Hadley cell transports, and the depth of the heat sink that is the Polar cell, ensures that the effects of transient weather phenomena are not only not felt by the system as a whole, but — except under unusual circumstances — are not even permitted to form. The endless chain of passing highs and lows which is part of everyday life for mid-latitude dwellers is unknown above the 60th and below the 30th parallels. There are some notable exceptions to this rule. In Europe, unstable weather extends to at least 70° north.
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Polar front:
http://en.wikipedia.org/wiki/P...ront
