War of Fire and Ice.(global warming)

Scientists agree that something is heating the atmosphere--they just can't agree on what. Greenhouse gases like carbon dioxide from auto engines and power plants have something to do with it. Now scientists think soot--tiny bits of carbon that blacken diesel exhaust and forest smoke--is another big culprit. Climate scientists James Hansen and Larissa Nazarenko at the National Aeronautics and Space Administration came to that conclusion after performing a computer analysis on data from a NASA spacecraft that monitors Earth's surface temperatures. Black soot in snow and ice may have caused as much as a quarter of the observed global warming over the last century--including the trend toward early springs in the north, thinning Arctic sea ice and melting land ice and permafrost.

When soot embeds itself in snow and ice, it absorbs sunlight, making Earth's nether regions less brilliantly reflective. Less sunlight gets reflected out into space and more energy stays behind, warming the oceans and land. Then the snow begins to melt, exposing even more carbon and intensifying the effect. That would help account for the greater warming at the poles, where average temperatures have risen 2.5 degrees Celsius in the past 50 years, compared to just over a quarter degree overall. The retreat of the glaciers--usually blamed entirely on greenhouse gases--may, in ...