Extreme weather across the northern hemisphere is just one consequence of Arctic warming (Image: Zackary Canepari/Panos Pictures)
Read more: “Climate change: It’s even worse than we thought“
In 2010, Russia sizzled as the temperature hit nearly 40 °C in several cities. In 2011, the “Groundhog Day blizzard” dumped astonishing amounts of snow across the eastern US and Canada. This year, too, has been , from summer deluges in the UK to a storm knocking out power to millions in the US – and of course, the devastation wrought by superstorm Sandy.
Such events fit a pattern. In a warming world, shifting rainfall and increased evaporation will lead to more droughts. A warmer atmosphere holds more water, making rainfall at times more intense.
It is difficult, though not impossible, to say how individual events are influenced by climate change. It is simpler to tell whether the overall numbers are increasing. Even at the time of the last IPCC report in 2007, the trends for , and intense rainfall were already clearly upward.
Not only are these trends continuing, but the weather is also becoming even more extreme than was predicted. For instance, a study this year of ocean-salinity data from between 1950 and 2000 by the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) found that the global water cycle – the rate at which water evaporates and falls as rain – has increased at . Work by researchers from Taiwan and China found that the increase in rainfall intensity…
