Michael Mann is a climatologist famous for bringing together a complete chronology of warming over the last 1000 years, using both instrumental records and historical proxies. Everyone has seen his "hockey stick" chart, though not all have been able to face the facts. The attacks motivated Mann to write a fierce response, called The Hockey Stick and the Climate Wars. which has been very favorably reviewed.
But forget all that for a moment: In a column for Daily Climate, Mann tells another story, about a time when he did not believe the prediction of leading climatologist James Hansen that we as a species had launched the greenhouse effect and begun to create a hellish-at-times climate.
It's really quite striking.
The first scientist to alert Americans to the prospect that human-caused climate change and global warming was already upon us was NASA climatologist James Hansen. In a sweltering Senate hall during the hot, dry summer of 1988, Hansen announced that "it is time to stop waffling…. The evidence is pretty strong that the [human-amplified] greenhouse effect is here."At the time, many scientists felt his announcement to be premature. I was among them.
I was a young graduate student researching the importance of natural – rather than human-caused – variations in temperature, and I felt that the "signal" of human-caused climate change had not yet emerged from the "noise" of natural, long-term climate variation.
That was one shift: into the greenhouse. Now, James Hansen warns, we're turning up the dial.
Back in December at the American Geophysical Union meeting, a huge meeting of physicists, climatologists, and other earthly scientists, Hansen alluded to the shocking nature of his research into extreme warming today. He said he and his colleagues had charted a "three sigma" (standard deviation) jump in warming/drying heat on the surface of the land in the U.S.
Today with his colleagues at GISS/NASA he has some more words with us, this time introducing his new paper, published in that most respected and open of journals, PNAS. Hansen, like Mann, thinks back on that fateful summer of l988.
He too can't quite believe it:
When I testified before the Senate in the hot summer of 1988 , I warned of the kind of future that climate change would bring to us and our planet. I painted a grim picture of the consequences of steadily increasing temperatures, driven by mankind’s use of fossil fuels.
But I have a confession to make: I was too optimistic.
My projections about increasing global temperature have been proved true. But I failed to fully explore how quickly that average rise would drive an increase in extreme weather.
In a new analysis of the past six decades of global temperatures, which will be published Monday, my colleagues and I have revealed a stunning increase in the frequency of extremely hot summers, with deeply troubling ramifications for not only our future but also for our present.
is not a climate model or a prediction but actual observations of weather events and temperatures that have happened. Our analysis shows that it is no longer enough to say that global warming will increase the likelihood of extreme weather and to repeat the caveat that no individual weather event can be directly linked to climate change. To the contrary, our analysis shows that, for the extreme hot weather of the recent past, there is virtually no explanation other than climate change.
The deadly European heat wave of 2003, the fiery Russian heat wave of 2010 and catastrophic droughts in Texas and Oklahoma last year can each be attributed to climate change. And once the data are gathered in a few weeks’ time, it’s likely that the same will be true for the extremely hot summer the United States is suffering through right now.
Maps in the study, which shows that extreme heating now reaches over 10% of the earth's surface, have the same coloration as a cover from The New Yorker's contest for a depiction of global warming.
Some scientists think Hansen has yet to prove the link between global warming and the kind of heat waves and drought that hit the Midwest this year, Texas last year, and Russia the year before.
But Hansen has a history of being right, from his seminal paper on the physics of cimate change, in l981, to his testimony, in l988, and in countless smaller instances. Veteran reporter Seth Borenstein for the AP nails down the details, making Hansen's point all the more convincing. :
In a landmark 1988 study, Hansen predicted that if greenhouse gas emissions continue, which they have, Washington, D.C., would have about nine days each year of 95 degrees or warmer in the decade of the 2010s. So far this year, with about four more weeks of summer, the city has had 23 days with 95 degrees or hotter temperatures.
Life in the greenhouse.