Satellites blow hot and cold over global warming New Scientist 15 March 97
MISLEADING satellite data may have led researchers to underestimate the impact of global warming. According to measurements made by several satellites since 1979, the lower atmosphere has been cooling by 0.05 'C each decade. The results had raised hopes that global warming had been over-estimated by ground-based measurements, which suggested that temperatures have increased by 0-13 'C per decade since 1979 (This Week, 7 April 1990, p 28). But two researchers in Colorado warn in this week's Nature (vol 386, p 164) that errors in the calibration of the instruments may have produced incorrect results. James Hurrell and Kevin Trenberth of the National Center for Atmospheric Research in Boulder have been trying to resolve the dis- crepancy between the two data sources. They used a computer model to try to filter out the effects of changes in the Earth's surface temperature on the atmosphere. During their analysis, they found that the satellite measurements changed abruptly twice, in mid-1981 and mid-1991. Those were two of a number of instances when one satellite took over from another. Hurrell says this suggests that the instruments on different satellites were not calibrated in the same way. He adds that discounting the sudden shifts as calibration errors leaves the satellite data showing a slight rise in temperature. "There are problems with the satellite records, so at least a portion of the cooling is spurious," says Hurrell. However, John Christy of the University of Alabama in Huntsville, who has found that balloon-home measurements confirm the satellite data, is not convinced by Hurrell and Trenberth's analysis. "They only have an inference-we have two different measurements," says Christy. Jeff Hecht, Boston
Salps may cool the heat if they survive and replicate Scientific American Dec 95
Salps may help to mitigate effects of global warming. Spread of salps into warmer water facilitates the transfer of carbon to deep ocean sediments in the fecal pellets which they dump a kilometre or so below the surface at night. However under too much warming they may choke on the mucus neck arising from too many phytoplankton.
The CO2 sceptics New Scientist 19 July 1997
The greenhouse sceptics base the core of their case on three factors:
As the world warms the heavens open New Scientist 4 Apr 98
IT NEVER rains, but it pours. That's the story across the US as global warming makes its mark. A survey of rainfall trends reveals that downpours have become more common, and days with moderate rainfall less frequent. David Easterling of the National Climatic Data Center in Asheville, North Carolina, told a meeting of the Association of American Geographers in Boston last week that total annual rainfall in different regions across the continental US has increased by between 5 and 20 per cent since 1910. The number of days with light showers has actually decreased, but this has been more than compensated for by a 1 per cent increase in the number of days in which rainfall across the continental US averages more than 5 centimetres. The finding is statistically significant because of the wide area covered. Spells of heavy rain lasting for several days have also become more common. The largest increases in rainfall have been in the Midwest and the Mississippi River valley, which was devastated by floods in 1993. The flooding followed many days of heavy rain, which saturated the soil. Climate models predict that higher temperatures will cause heavier precipitation at high latitudes, and there is evidence that temperatures are rising. For example, records show that the number of days with below-freezing temperatures has decreased across most of the US since 1948. Jeff Hecht, Boston