Sunday, July 17, 2011

The number of coal-fired power stations in China multiplied enormously in that period: the electricity-generating capacity rose from just over 10 gigawatts (GW) in 2002 to over 80GW in 2006 (a large plant has about 1GW capacity).

The effect also explains the lack of global temperature rise seen between 1940 and 1970: the effect of the sulphur emissions from increased coal burning outpaced that of carbon emissions, until acid rain controls were introduced, after which temperature rose quickly. Some have even proposed sulphur dioxide could used to geoengineer the planet by deliberately injecting millions of tonnes into the atmosphere to combat warming.

The new study, published in the Proceedings of the National Academy of Sciences on Monday, analysed possible reasons for the flat 1998-2008 temperature trend using climate models and concluded that it was unlikely to be due simply to the random variation inherent in the planet's climate system. Instead it found the effect of sulphur, the sun and El Ni?o dominated, with the El Ni?o climate phase peaking in 1998 – the hottest year ever recorded – then moving into a phase dominated by its cooler mirror image, La Ni?a. The scientists ruled out changes in water vapour or carbon soot in the atmosphere as significant factors.


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