What's the Latest Development?

A new report compiled by nearly 400 scientists from 48 countries explains how climate change may have influenced certain individual weather events this year, from droughts and heat waves in the US and Africa to extreme temperature variability in the UK. While the report emphasizes the role of well-understood phenomena, like La Niña, it also examines more anomalous extreme weather. "2011 was notable for many extreme weather and climate events. La Niña played a key role in many, but certainly not all of them," said Tom Karl, director of the National Oceanic and Atmospheric Administration (NOAA)'s National Climatic Center.

What's the Big Idea?

Authors of the study found that a heat wave is now around 20 times more likely during a La Niña year than it was during the 1960s, and that frigid Decembers are half as likely to occur now compared to 50 years ago. "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." Scientists liken carbon's role in climate change to the effect of steroids on a baseball player. While steroids are likely the cause of improved performance, a natural variability in the player's swings must be accounted for. 

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