Friday, September 20, 2013

Yes, it is due to global warming!

A glance through climate change news will show the growing gap between believers and deniers even today. Is the climate disruption we are witnessing linked to global warming, is still contested. New research released yesterday links human-caused climate change to six of 12 extreme weather events from 2012. Teams of scientists from around the world examined the causes behind extreme weather events on five continents and in the Arctic. Their results were published as a special report in the Bulletin of the American Meteorological Society.

One of the stronger linkages between
global warming and severe weather was found in an analysis of last year's high July temperatures in the northeastern and north-central United States. The Stanford team found that climate change had made the likelihood of such a heat wave four times more likely than in a world without elevated levels of greenhouse gases. They were able to determine this by running models with current levels of greenhouse gases as well as ones that reflected preindustrial levels and examining the relative likelihood of the heat wave.
Others looked at 2012's hot spring temperatures over the eastern United States and also found that human influences contributed about 35 percent to late spring heat that year.
In some other parts of the world, climate change was linked, although in a small way, to extreme precipitation events. New Zealand experienced an extreme two-day rainfall in December 2011; researchers said 1 to 5 percent more moisture was available for that event due to climate change, which is increasing the amount of water vapor in the atmosphere.
Australia also experienced record rainfall in early 2012, and while La NiƱa, a natural variation, was behind much of that, researchers found that human-caused climate change increased the chance of the above-average rainfall by 5 to 15 percent.

This is the second time the Bulletin of the American Meteorological Society has collected information on the previous year's weather extremes and tried to tease out the role of climate change in those events. The researchers involved in the effort stressed that the science of attribution, or of linking specific events to climate change, is still young and evolving.

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