Geophysical Research Letters


Do Extreme Climate Events Require Extreme Forcings?
Geophysical Research Letters

The question whether extreme climate events require extreme forcings is assessed for the severe Great Plains drought during May-July 2012. This drought event had a rapid onset, and little indications or early warnings for its sudden emergence existed. The analysis of its origins is based on a dynamical seasonal climate forecast system where states of the ocean, atmosphere, land, sea ice, and atmospheric trace gases were initialized in late April 2012 and an ensemble of forecasts was made. Based on diagnosis of a spectrum of possible outcomes for precipitation over the Great Plains from this system, it is concluded that the extreme Great Plains drought did not require extreme external forcings, and could plausibly have arisen from atmospheric noise alone. Implications for developing early warning system for extreme events in general are also discussed.

Dans son discours sur le « réchauffement climatique » prononcé hier, Barack Obama a imputé aux gaz à effet de serre la grande sécheresse de 2012. Pourtant, un article scientifique publié la semaine dernière démontre clairement que ce n’est pas le cas… Obama, menteur ou ignorant?

N.B. Dans les publications scientifiques, le terme « forcing » fait référence aux émissions de gaz à effet de serre.