The results, just published in a refereed scientific journal, showed that the depletion of the ozone layer over Antarctica had temporarily shifted atmospheric conditions in a way that cooled the region, but that as the layer heals in coming decades, Antarctica would quickly warm.
Shifting atmospheric pressure.
The trend appears linked to a long-term shift in atmospheric pressure and winds around the North Pole and could also be related to global warming, the researchers said.
So climatologist James Elsner of Florida State University in Tallahassee and his colleagues looked for ties between hurricane tracks and the North Atlantic Oscillation (NAO), a seesaw shift in atmospheric pressures over the ocean (Science, 12 February 1999, p. 948).
Further, some have estimated the real number of marchers as 400,000, and if the global estimates swell equally, then globally about the same proportion were marching as the CO2 growth since industrialization is a shift in atmospheric composition.
Dr. Shepherd said this might be due to shifts in atmospheric circulation patterns caused by the warming itself.
And variations in the thickness and extent of sea ice cloaking the Arctic Ocean are driven by yet another set of complicating factors, ranging from long-term shifts in atmospheric pressure patterns to events as close-focus as the potent Arctic superstorm I reported on earlier this month.
Similarly, changes in mineralogy reflect (a) source area mineralogy and weathering and (b) shifts in atmospheric transport.
Lamont team member Richard Seager says that his group's model presents a more realistic view of the Pacific, which allows the model to respond more strongly to shifts in atmospheric circulation caused by greenhouse warming.
As any pilot will attest, air density is perhaps the single most important factor affecting aircraft performance and while the Mi-17 is not immune to shifts in atmospheric pressure, it has proven to be a very reliable platform in "hot and high" environments like Afghanistan.
