Models Predict Global Emergence of Unprecedented Heat in the 20th and 21st Centuries


New research in Climatic Change finds that many areas of the globe are likely to permanently move into an unprecedented extreme heat regime over the next four decades should greenhouse gas concentrations continue to increase. The study, partially funded by DOE and conducted by scientists at Stanford University, includes analyses of a large suite of global climate model experiments and observational data revealing that global warming is already resulting in a novel heat regime. In addition, the authors find that global climate models are able to capture the observed intensification of seasonal hot conditions, demonstrating emergence of an extreme heat regime in which the coolest summer of the 21st century is hotter than the hottest summer of the late 20th century. In contrast to the common perception that high-latitude areas face the most accelerated response to global warming, the results demonstrate that tropical areas may exhibit the most immediate and robust emergence of unprecedented heat, occurring within the next two decades. The research implies that many areas outside of the tropics may exhibit a 50% likelihood of permanent emergence by the mid 21st century, including areas of the United States, Europe, and China, even with relatively moderate average global warming.


Diffenbaugh, N. S., and M. Scherer. 2011. ÔÇťObservational and Model Evidence for Global Emergence of Unprecedented Heat in the 20th and 21st Centuries, Climatic Change, DOI:10.1007/s10584-011-0112-y.