The nation’s best-known and most prescient climatologist, NASA’s James Hansen, has a must-read op-ed in the Washington Post.
Here’s how “Climate Change Is Here — And Worse Than We Thought” opens:
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.
This 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.
I first wrote about this back in January when Hansen posted the draft of his findings, which made use of a detailed climatological analysis (see “Hansen et al: “Extreme Heat Waves … in Texas and Oklahoma in 2011 and Moscow in 2010 Were ‘Caused’ by Global Warming”).
Hansen has a good figure to show what’s happening:
Frequency of occurrence (vertical axis) of local June-July-August temperature anomalies (relative to 1951-1980 mean) for Northern Hemisphere land in units of local standard deviation (horizontal axis). Temperature anomalies in the period 1951-1980 match closely the normal distribution (“bell curve”, shown in green), which is used to define cold (blue), typical (white) and hot (red) seasons, each with probability 33.3%. The distribution of anomalies has shifted to the right as a consequence of the global warming of the past three decades such that cool summers now cover only half of one side of a six-sided die, white covers one side, red covers four sides, and an extremely hot (red-brown) anomaly covers half of one side.
Hansen’s climate analyses and warnings need to be heeded for two reasons. First, this analysis is supported by other recent papers, such as “Study Finds 80% Chance Russia’s 2010 July Heat Record Would Not Have Occurred Without Climate Warming” and “Nature: Strong Evidence Manmade ‘Unprecedented Heat And Rainfall Extremes Are Here … Causing Intense Human Suffering’.”
Second, Hansen has been right longer than almost anyone else around (see “Right for 27 years: 1981 Hansen study finds warming trend that could raise sea levels” and “Lessons From Past Predictions: Hansen 1981“).
Hansen’s mastery of climate science is quite literally what gives him climate prescience. We ignore him at our grave peril.
UPDATE: The AP’s excellent climate reporter, Seth Borenstein has a good piece up on Hansen’s new analysis, “New study links current events to climate change.” The AP has quotes from some credible independent experts:
The science in Hansen’s study is excellent “and reframes the question,” said Andrew Weaver, a climate scientist at the University of Victoria in British Columbia who was a member of the Nobel Prize-winning international panel of climate scientists that issued a series of reports on global warming.”Rather than say, ‘Is this because of climate change?’ That’s the wrong question. What you can say is, ‘How likely is this to have occurred with the absence of global warming?’ It’s so extraordinarily unlikely that it has to be due to global warming,” Weaver said….
Another upcoming study by Kevin Trenberth, climate analysis chief at the National Center for Atmospheric Research, links the 2010 Russian heat wave to global warming by looking at the underlying weather that caused the heat wave. He called Hansen’s paper an important one that helps communicate the problem….
White House science adviser John Holdren praised the paper’s findings in a statement. But he also said it is true that scientists can’t blame single events on global warming: “This work, which finds that extremely hot summers are over 10 times more common than they used to be, reinforces many other lines of evidence showing that climate change is occurring and that it is harmful.”
… Granger Morgan, head of engineering and public policy at Carnegie Mellon University, called Hansen’s study “an important next step in what I expect will be a growing set of statistically-based arguments.”
Here’s more from the Hansen op-ed: