NYT: The Basics: Connecting the Global Warming Dots (with graphic)

[DeepModem Mom]

The Basics
Connecting the Global Warming Dots
By ANDREW C. REVKIN
Published: January 14, 2007

....The impact of a buildup of carbon dioxide and other greenhouse gases is now largely undisputed. Almost everyone in the field says the consequences can essentially be reduced to a formula: More CO2 = warmer world = less ice = higher seas. (Throw in a lot of climate shifts and acidifying oceans for good measure.)...

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In the (Intergovernmental Panel on Climate Change's) last report, issued in 2001, and in more recent studies reviewed for the coming report, various trends provide clues that human activity, rather than natural phenomena, probably caused most of the recent warming. A number of trends have been identified:

¶The global average minimum nighttime temperature has risen. (This is unlikely to be caused by some variability in the sun, for example, and appears linked to the greenhouse gases that hold in heat radiating from the earth’s surface, even after the sun has gone down.)

¶The stratosphere, high above the earth’s surface, has cooled, which is an expected outcome of having more heat trapped by the gases closer to the surface, in the troposphere. (Scientists say that variations in the sun’s output, for example, would instead cause similar trends in the two atmospheric layers instead of opposite ones.)

¶There has been a parallel warming trend over land and oceans. (In other words, the increase in the amount of heat-trapping asphalt cannot be the only culprit.)...

Another important finding comes from computer simulations of the climate system. While the several dozen top models remain rough approximations, they have become progressively better at replicating climate patterns, past and present.

In the models, the only way to replicate the remarkable warming, and extraordinary Arctic warming, of recent decades is to add greenhouse gases as people have been doing, Dr. (Jay Lawrimore, chief of the climate monitoring branch of the National Climatic Data Center in Asheville, N.C.) said....

http://www.nytimes.com/2007/01/14/weekinreview/14basics.html