Does Gore overheat global warming?

Glaciologists also caution that calving ice is only half the equation: You must balance what an ice sheet loses at the edges against what it gains in the interior through snowfall. Projections of global warming's effect on these two vast ice sheets point to thickening in the interior from increased precipitation, which researchers say is happening. The sheets were in "near balance" from the 1960s perhaps through the 1980s, says Richard Alley, a glaciologist at Penn State University in College Park. "The Greenland picture is starting to come into focus - very recently, melting has gone up more than snowfall ... and the ice sheet is shrinking. Confidence is not 100 percent, because these are hard measurements to make and it's a short data set." He says that Antarctica appears to be following suit.

Some researchers point to the last UN summary of climate science, published in 2001, which indicated that no significant trends in tropical storm strength or numbers have appeared in data for the 20th century. Within the past year, however, several studies have been published that find a trend toward stronger tropical cyclones worldwide. The results have triggered an intense debate among hurricane specialists - not surprising given the stakes, the poor quality of some historical hurricane data, and the "freshness" of the latest results. If the results hold up, they would bolster conclusions from modeling studies that point to more intense tropical cyclones in a warmer world. Meanwhile, trends in rainfall and drought intensity are appearing that are consistent with those projected by global-warming models, researchers add.

The movie is about climate, not marine life. And in many respects, this phenomenon is less controversial because its chemistry is so straightforward, says Victoria Fabry, a marine science professor at California State University at San Marcos. But it's no less critical, she says, because it has implications for the ocean food chain.

The oceans take up CO2 via biological processes. They also take up CO2 via seawater chemistry, which can lead to a more-acidic ocean. So far, the decline in pH, a measure of acidity and alkalinity, looks tiny. But marine life is sensitive to small changes; the net result is to reduce the amount of calcium carbonate that corals need and critters at the bottom of the food chain use to build their shells. This spring, researchers with the National Oceanic and Atmospheric Administration wrapped up a research trip from Tahiti to Alaska, sampling water chemistry. The team, led by oceanographer Richard Feely, notes that, over large sections of the north Pacific, it found evidence of acidification attributable for the most part to ocean uptake of the CO2 humans have pumped into the atmosphere over the past 15 years - consistent with model projections.

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