Saigon
Gold Member
Following on from another thread about the massive loss of Arcti Ice, SSDD asked:
And I promised to explain that in a little detail. This is a little complicated, so bear with me. I have put most of this in my own words, but also deliberately chosen a source which explains the concepts in terms I think everyone can understand without reading 500 pages of text. I have then linked a scientific study at the bottom for those more interested in the details.
1) The Arctic is an area of ocean surrounded by land. Antarctica is a continent surrounded by oceans. The Arctic is flat; the Antarctic mountainous. The Arctic is sea ice, much of the Antarctic is glaciers and land ice. In geographical terms, they are opposites. Hence, comparing what is happening in one with the other is not comparing like-with-like. The Arctic has lost around 40% of its ice - the Antartic gained around 5%, so the idea that the net result is static is clearly false.
2) Antarctica has two distinct climactic and geogrpahical zones - west and east. The west is warming and shedding massive amounts of ice into the sea. The east is gaining ice. Why this is, is the basis of SSDD's question.
3) During the satellite era (1979-present), no significant net reduction in Antarctic sea ice extent has been measured, although there are significant reductions around the Antarctic Peninsula with compensating increases elsewhere.
4) Temperatures in the Antartic are rising. Bt temperatures are not the only influence on icing. Source: http://psc.apl.washington.edu/zhang/Pubs/Zhang_Antarctic_20-11-2515.pdf
The Arctic responds much more directly to changes in air and sea-surface temperatures than Antarctica, because it is ocean surrounded by land. The climate of Antarctica is governed much more by wind and ocean currents. Some studies indicate climate change has strengthened westerly winds in the Southern Hemisphere, and because wind has a cooling effect, scientists say this partly accounts for the marginal increase in sea ice levels that have been observed in the Antarctic in recent decades.
"Another reason why the sea-ice extent in the Antarctic is remaining fairly high is, interestingly, the ozone hole," Serreze told LLM. This hole was carved out over time by chlorofluorocarbons, toxic chemicals formerly that were used in air conditioners and solvents before being banned. "The ozone hole affects the circulation of the atmosphere down there. Because of the ozone hole, the stratosphere above Antarctica is quite cold. Ozone in the stratosphere absorbs UV light, and less absorption [by] ozone makes the stratosphere really cold. This cold air propagates down to the surface by influencing the atmospheric circulation in the Antarctic, and that keeps the sea ice extensive."
Record-High Antarctic Sea Ice Levels Don't Disprove Global Warming | Ice Cap Melting | LifesLittleMysteries.com
Conclusions from the British Antarctic Survey:
“Until now these changes in ice drift were only speculated upon, using computer models of Antarctic winds. This study of direct satellite observations shows the complexity of climate change. The total Antarctic sea-ice cover is increasing slowly, but individual regions are actually experiencing much larger gains and losses that are almost offsetting each other overall. We now know that these regional changes are caused by changes in the winds, which in turn affect the ice cover through changes in both ice drift and air temperature. The changes in ice drift also suggest large changes in the ocean surrounding Antarctica, which is very sensitive to the cold and salty water produced by sea-ice growth.
Press Release - Why Antarctic sea ice cover has increased under the effects of climate change - British Antarctic Survey
Antarctic Sea Ice
I am interested in all comments, of course, but I particularly ask SSDD and Westwall to comment on the scientific concepts involved.
And I promised to explain that in a little detail. This is a little complicated, so bear with me. I have put most of this in my own words, but also deliberately chosen a source which explains the concepts in terms I think everyone can understand without reading 500 pages of text. I have then linked a scientific study at the bottom for those more interested in the details.
1) The Arctic is an area of ocean surrounded by land. Antarctica is a continent surrounded by oceans. The Arctic is flat; the Antarctic mountainous. The Arctic is sea ice, much of the Antarctic is glaciers and land ice. In geographical terms, they are opposites. Hence, comparing what is happening in one with the other is not comparing like-with-like. The Arctic has lost around 40% of its ice - the Antartic gained around 5%, so the idea that the net result is static is clearly false.
2) Antarctica has two distinct climactic and geogrpahical zones - west and east. The west is warming and shedding massive amounts of ice into the sea. The east is gaining ice. Why this is, is the basis of SSDD's question.
3) During the satellite era (1979-present), no significant net reduction in Antarctic sea ice extent has been measured, although there are significant reductions around the Antarctic Peninsula with compensating increases elsewhere.
4) Temperatures in the Antartic are rising. Bt temperatures are not the only influence on icing. Source: http://psc.apl.washington.edu/zhang/Pubs/Zhang_Antarctic_20-11-2515.pdf
The Arctic responds much more directly to changes in air and sea-surface temperatures than Antarctica, because it is ocean surrounded by land. The climate of Antarctica is governed much more by wind and ocean currents. Some studies indicate climate change has strengthened westerly winds in the Southern Hemisphere, and because wind has a cooling effect, scientists say this partly accounts for the marginal increase in sea ice levels that have been observed in the Antarctic in recent decades.
"Another reason why the sea-ice extent in the Antarctic is remaining fairly high is, interestingly, the ozone hole," Serreze told LLM. This hole was carved out over time by chlorofluorocarbons, toxic chemicals formerly that were used in air conditioners and solvents before being banned. "The ozone hole affects the circulation of the atmosphere down there. Because of the ozone hole, the stratosphere above Antarctica is quite cold. Ozone in the stratosphere absorbs UV light, and less absorption [by] ozone makes the stratosphere really cold. This cold air propagates down to the surface by influencing the atmospheric circulation in the Antarctic, and that keeps the sea ice extensive."
Record-High Antarctic Sea Ice Levels Don't Disprove Global Warming | Ice Cap Melting | LifesLittleMysteries.com
Conclusions from the British Antarctic Survey:
“Until now these changes in ice drift were only speculated upon, using computer models of Antarctic winds. This study of direct satellite observations shows the complexity of climate change. The total Antarctic sea-ice cover is increasing slowly, but individual regions are actually experiencing much larger gains and losses that are almost offsetting each other overall. We now know that these regional changes are caused by changes in the winds, which in turn affect the ice cover through changes in both ice drift and air temperature. The changes in ice drift also suggest large changes in the ocean surrounding Antarctica, which is very sensitive to the cold and salty water produced by sea-ice growth.
Press Release - Why Antarctic sea ice cover has increased under the effects of climate change - British Antarctic Survey
Antarctic Sea Ice
I am interested in all comments, of course, but I particularly ask SSDD and Westwall to comment on the scientific concepts involved.
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At least the computer models are updated, one would hope the same could be said about your flawed understanding of physics.
