It’s Not Your Imagination. Summers Are Getting Hotter.
By Nadja Popovich and Adam Pearce, NY Times, July 28, 2017
Extraordinarily hot summers--the kind that were virtually unheard-of in the 1950s--have become commonplace.
This year’s scorching summer events, like heat waves rolling through southern Europe and temperatures nearing 130 degrees Fahrenheit in Pakistan, are part of this broader trend.
James Hansen, a retired NASA climate scientist and professor at Columbia University, shows how summer temperatures have shifted toward more extreme heat over the past several decades.
Dr. Hansen and two colleagues compared actual summer temperatures for each decade since the 1980s to a fixed baseline average. During the base period, 1951 to 1980, about a third of local summer temperatures across the Northern Hemisphere were in what they called a “near average” or normal range. A third were considered cold; a third were hot.
Since then, summer temperatures have shifted drastically, the researchers found. Between 2005 and 2015, two-thirds of values were in the hot category, and nearly 15 percent were in a new category: extremely hot.
Practically, that means most summers are now either hot or extremely hot compared with the mid-20th century.
The big increase in summer temperatures under the category of extreme heat is “right in line” with what scientists expect to see as the climate warms over all, said Todd Sanford, director of research at Climate Central, a nonprofit science and news organization.
