Can't stand the heat

 作者:项矛撷     |      日期:2019-03-08 08:09:07
By Fred Pearce WHEN Al Gore claimed that this July was the warmest for 600 years, climatologists accused the American Vice-President of understatement. “It’s not just July,” says David Parker of Britain’s Meteorological Office. “Every month until September was the warmest on record.” In the first three-quarters of 1998, the world was 0.64 °C hotter than the average over the same months from 1951 to 1990, and considerably warmer than the second hottest year, 1997. Thermometer records, which go back some 130 years, and tree rings and ice cores from earlier times, corroborate the claim that we’ve seen nothing like it since at least the Middle Ages. The causes of this year’s exceptional heat, and much of the wild weather that came with it, were twofold: first, the continuing greenhouse effect, which has led to record temperatures throughout the 1980s and 1990s; and second, the wash of warm water across the Pacific caused by the most intense outbreak for at least 50 years of the phenomenon known as El Niño, which reached its peak early in the year. El Niño played havoc with normal climate patterns, triggering forest fires, floods, disease, famine and widespread disruption to fisheries and agriculture (see map). There were beneficiaries, too, such as Darwin’s finches on the Galápagos Islands, which went into reproductive overdrive as rain fell on the normally arid islands, and Californian surfers who enjoyed 12-metre waves brought about by a reversal of prevailing winds. El Niño starts as a build-up of heat in the western Pacific and results in a large body of warm water moving eastwards across the ocean. What causes this sudden flux is hotly disputed. William Gray, an oceanographer at Colorado State University, suggested this year that the great landmass of Eurasia absorbs so much solar heat that from time to time it releases some into the Pacific as a kind of safety valve. One theory is that, as the world becomes warmer, this safety valve operates more often and more intensely—as it appears to have in the past 20 years. Parker says that El Niño roughly doubled the effect of global warming this year. But he suggests that the greenhouse effect may itself have made El Niño more intense. However, Gray points out that El Niño has always been more active in some decades than others. Whatever the truth, the sweltering heat added urgency to negotiations on limiting industrial emissions of greenhouse gases, which most scientists agree are contributing to global warming. Gore used his “hot July” theme to propose a $3.6 billion programme of tax credits to encourage energy efficiency—part of a plan to implement targets agreed at the UN climate summit in Kyoto in 1997. But Congress, under pressure from industry, easily stonewalled the plans of the administration and reduced the programme to just $1 billion. In the run-up to the Buenos Aires climate conference in November, however, some sections of the corporate world appeared to be adopting a greener agenda. The oil giant BP pledged to cut its greenhouse gas emissions by 10 per cent by 2010. Investment in solar energy soared. And an increasing number of companies backed plans for a global trade in permits to emit greenhouse gases. As the spectre of recession closes in on the world economy,