2016-05-08
WASHINGTON, July 10, 2012 (AFP) - Severe droughts, floods and heat waves rocked the world last year as greenhouse gas levels climbed, boosting the odds of some extreme weather events, international scientists said Tuesday.
The details are contained in the annual State of the Climate report, compiled by nearly 400 scientists from 48 countries and published in the peer-reviewed Bulletin of the American Meteorological Society.
The report itself remains "consciously conservative" when it comes to attributing the causes of certain weather events to climate change, and instead refers only to widely understood phenomena such as
"2011 was notable for many extreme weather and climate events.
Last year was among the 15 warmest since records began in the late 1800s, and the
Greenhouse gases from human pollution sources like coal and gas reached a new high, with carbon dioxide emissions exceeding 390 parts per million -- up 2.10 parts per million from 2010 -- for the first time since modern records began.
Despite the natural cooling trend brought by back-to-back
The double
An accompanying analysis in the same journal, titled "Explaining Extreme Events," examined the links between human-driven climate change and six selected weather crises in 2011, including the
The authors found that "such a heat wave is now around 20 times more likely during a
"We have shown that climate change has indeed altered the odds of some of the events that have occurred," he told reporters. "What we are saying here is we can actually quantify those changing odds."
Looking at
However, a close look at the floods along the
The damage caused by the floods was unprecedented, but the amount of rain that actually fell "was not very unusual," said the analysis by experts from NOAA and
While it remains hard to link single events to human-caused climate change, "scientific thinking has moved on and now it is widely accepted that attribution statements about individual weather or climate events are possible," the report added.
The key is analyzing to what extent climate change may be boosting the odds of extreme weather, said the report, likening the phenomenon to a baseball player who takes steroids and then starts getting 20 percent more hits than before.
Scientists can consider steroids as the likely cause for the increase in hits, but must still take care to account for natural variability in the player's swing.
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