Aug 5, 2010

Bombshell: Study Finds 80% Chance Russia’s 2010 July Heat Record Would Not Have Occurred Without Climate Warming

Joe Romm
Think Progress

A major new study has reanalyzed the connection between global warming and the record-breaking temperatures we’ve been seeing.  Stefan Rahmstorf and Dim Coumou conclude in their PNAS paper, “Increase of extreme events in a warming world“:

… the majority of monthly records like the Moscow heat wave must be considered due to the warming trend. In highly aggregated data with small variability compared to the trend, like the global-mean temperature, almost all recent records are due to climate warming.

Basically, they show that when there is a lot of variability in temperature, as there is on in individual days, finding a trend in extreme records at any single location thanks to global warming is small:  “daily data from a single weather station may not yet show a major change in temperature extremes due to global warming.”

But when you look at the monthly and especially yearly temperature data at a location, data that have considerable less fluctuation, then a warming trend is far more likely to create a new record.  And as lead author Rahmstorf explained to me, this matters because “monthly temperature records have much more impact on human society” in terms of impact on human health, mortality, and crop failures