Dec 11, 2012

Global increase in record-breaking monthly-mean temperatures

Dim Coumou, Alexander Robinson, Stefan Rahmstorf
Climatic Change
  • Analyzes 131-years (1880–2010) of climate data and finds that the number of local record-breaking monthly temperature extremes is now on average five times larger than expected in a climate with no long-term warming
  • Finds that continental regions with an exceptionally large number of 131-year records in the last decade (2001–2010) are primarily located in the tropics and include East Africa, India and Amazonia
  • Finds that, globally, the probability that the records set in between 2001-2010 due to the long-term warming rather than stationary variability is more than 80%; an alternative way of saying this is, on average there is an 80 % chance that a new monthly heat record is due to climatic change
  • Identifies notable exceptions, including: the eastern U.S., Australia, Southeast Asia and Argentina, where probabilities range from about 10 to 50 % depending on the specific location
  • States that large regional differences exist in the number of observed records
  • Finds summertime records, which are associated with prolonged heat waves, increased by more than a factor of ten in some continental regions including parts of Europe, Africa, southern Asia and Amazonia
  • Finds that the observed records cluster both in space and in time
  • Finds that strong El Niño years see additional records superimposed on the expected long-term rise
  • Predicts that under a medium global warming scenario, by the 2040s the number of monthly heat records globally to be more than 12 times as high as in a climate with no long-term warming