Climate watch

Most people get their news about global warming second-hand, but for those who want to keep their own finger on the pulse of the planet, two Web sites merit special interest.

One site shrewdly keeps tabs on the coldest regions of the world--the high latitudes and high altitudes, collectively known as the cryosphere--because they are the regions most sensitive to global climate change. The reason for the sensitivity is that water there can readily shift back and forth between its liquid and solid phases, with dramatic results. Run by the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado, the Web site reports conditions in the cryosphere on the basis of remote sensing from satellites and aircraft. The site tracks the waxing and waning of snow cover, glaciers, sea ice, and ice shelves. It also monitors rising sea levels and conditions in the permafrost. In its "State of the Cryosphere" (nsidc.org/sotc/intro. html), the NSIDC reports that "regardless of parameter or measurement method, the amount of snow and ice has been decreasing over the past several decades."

A more anecdotal look at global climate change in the polar regions and elsewhere can be found at "Global Warming: Early Warning Signs" (www.climatehotmap.org). Created by several leading environmental groups, the site has a world map you can click on to learn about the "fingerprints" and "harbingers" of climate change. The site also includes a report on the potential consequences of the warming climate for different regions of the United States and for sectors ranging from agriculture to human health.

Robert Anderson is a freelance science writer living in Los Angeles.

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