'Irreversible' Hot Summers: The New Climate Reality

“The fact that we're already seeing these changes in historical weather observations, and that they match climate model simulations so closely, increases our confidence that our projections of permanent escalations in seasonal temperatures within the next few decades are well founded." — Noah Diffenbaugh.

A new study suggests that the tropics and much of the Northern Hemisphere are likely to soon experience irreversible rises in summertime temperatures if greenhouse gas emissions continue at least at their current rates.

“According to our projections, large areas of the globe are likely to warm up so quickly that, by the middle of this century, even the coolest summers will be hotter than the hottest summers of the past 50 years," said the study's lead author, Noah Diffenbaugh.

He's a fellow at the Woods Institute for the Environment at Stanford University.

Diffenbaugh and colleague Martin Scherer, writing in the journal Climatic Change, also concluded that many tropical regions in Africa, Asia and South America could see “the permanent emergence of unprecedented summer heat” in the next two decades.

They write that current climate models, using historical data from weather stations around the world, accurately “predict” the recent record heat waves that have already emerged in several parts of the planet.

Diffenbaugh says he was surprised to see how quickly potentially destructive heat zones are likely to emerge based on the calculations of 50 climate model experiments.

He warns that the new heat regime could have acute consequences for human health, agriculture and wildlife.

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