Half of extreme weather events of 2012 are related to greenhouse gas emissions
Hurricane Sandy, torrential rains in Britain or China, drought in East Africa, heat wave in the eastern United States … 18 research teams have studied the twelve climatic events exceptional intensity of the year.
Dramatic Sky over Bucharest, Romania
global warming, resulting in emissions of greenhouse gases emissions produced by human activities, has contributed to half of the extreme weather on the planet in 2012, said researchers from 18 research teams in a report released on Thursday September 5. The researchers analyzed the causes of twelve exceptional intensity weather events of 2012.
difficult cases to identify
report published in the Bulletin of the American Meteorological Society says that “ natural weather processes and normal climate fluctuations have played a key role in these phenomena” . However, the authors add, “ in some cases, the analysis makes clear that climate change caused by emissions of greenhouse gases from human activities has contributed to these phenomena” .However
“determine the causes of these phenomena remains a challenge,” , by Thomas Karl, director of the National Climatic Data Center in the U.S. Oceanographic and Atmospheric Agency (NOAA). The objective of this research is to understand whether these weather events could occur more frequently and “ if their greater intensity due to natural factors or human activity related to” , he said.
extreme weather events linked to human activities
human impact on the climate may be partly responsible for the exceptional rainfall in Australia, the winter unprecedented drought in southern Europe and drought in East Africa, according to the report. Similarly, heavy rains in New Zealand in late 2011 likely result of global warming: increased humidity, produced by the accumulation of greenhouse gas emissions would cause precipitation. Finally, the heat wave in the eastern United States in the spring of 2012 is a case study where human influence is more convincing to the researchers that 35% of this phenomenon can be attributed to climate change.
However, the report concludes that the 2012 drought in the central United States can be explained largely by independent natural atmospheric factors of global warming.
Hurricane Sandy, which ravaged the coasts of the states of New Jersey and New York, is particularly complex for scientists. Human influence is very unclear and “ many factors intervened to produce such power” according to the report.
issue of rising sea levels
If weather events in 2012 were particularly extreme in the future hurricanes of lesser intensity may produce similar devastation due to the higher level of the ocean, which is mainly due to the melting of Arctic ice, due part to global warming. Arctic sea ice has experienced during the summer of 2012 a record decline, with reduced 3.41 million sq km area. “ This phenomenon can not be explained only by natural variations” , the statement said.
In its latest draft report, a summary of which was leaked to the press in August 2013, the Intergovernmental Panel on Climate Change (IPCC) considers “ highly likely that human influence on climate is responsible for more than half of the rise in surface temperature of the globe between 1951 and 2010 “. The final version of this document will be published in late September in Stockholm.