Climate-change skeptics dispute such statistical arguments, contending that climatologists do not know enough about long-range patterns to draw definitive links between global warming and weather extremes. They cite events like the heat and drought of the 1930s as evidence that extreme weather is nothing new. Those were indeed dire heat waves, contributing to the Dust Bowl, which dislocated millions of Americans and changed the population structure of the United States.
But most researchers trained in climate analysis, while acknowledging that weather data in parts of the world are not as good as they would like, offer evidence to show that weather extremes are getting worse.
The Nashville flood earlier this year was largely ignored by the national press – but not today, when it figures into the liberal argument. Gillis began:
The floods battered New England, then Nashville, then Arkansas, then Oklahoma — and were followed by a deluge in Pakistan that has upended the lives of 20 million people.
The summer’s heat waves baked the eastern United States, parts of Africa and eastern Asia, and above all Russia, which lost millions of acres of wheat and thousands of lives in a drought worse than any other in the historical record.
Seemingly disconnected, these far-flung disasters are reviving the question of whether global warming is causing more weather extremes.
The collective answer of the scientific community can be boiled down to a single word: probably.
The story also ended on the familiar note that carbon overload is a constantly unfolding humanitarian disaster:
Certain recent weather events were so extreme that a few scientists are shedding their traditional reluctance to ascribe specific disasters to global warming.
After a heat wave in Europe in 2003 that killed an estimated 50,000 people, the worst such catastrophe for that region in the historical record, scientists published detailed analyses suggesting that it would not have been as severe in a climate uninfluenced by greenhouse gases.
And Dr. Trenberth has published work suggesting that Hurricane Katrina dumped at least somewhat more rain on the Gulf Coast because the storm was intensified by global warming.
“It’s not the right question to ask if this storm or that storm is due to global warming, or is it natural variability,” Dr. Trenberth said. “Nowadays, there’s always an element of both.”