Update 9am Saturday: I'd like to direct your attention to the comments as there is an important discussion as to whether Scenario A or B is the correct interpretation of Dr. Hansen's paper.
WASHINGTON — The relentless, weather-gone-crazy type of heat that has blistered the United States and other parts of the world in recent years is so rare that it can't be anything but man-made global warming, says a new statistical analysis from a top government scientist.
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.
Hansen says now he underestimated how bad things would get.
--- Story by the Associated Press' Seth Borenstein
If Google News is correct, 430 news outlets ran with this story. Not only did I read it in yesterday's Wichita Eagle, I saw it on ABC News. But, does it convey an accurate picture of the science? I -- strongly -- do not believe so.
Let's break it down.
Below is Dr. Hansen's (fyi: not an atmospheric scientist) study. I have the entire paper and I have read it several times.
The part of the paper that, for a quarter of a century, has received the most attention is his forecast of future world temperatures. He keeps a copy of the forecast and a running tally of actual temperatures on his web site and it can be viewed here (scroll down to middle of page). I've placed a screen capture below.
In his paper, he posited three "scenarios." Scenario A was the worst case where CO2 levels continued to rise and the corresponding temperatures. "B" was the middle case where CO2 rises at a lesser rate (the blue line). Scenario C was the forecast of temperatures if CO2 levels were restrained beginning in the 1990's and continued to fall into the 21st Century. That is the purple forecast temperatures. The actual temperatures are the black line.
Turns out that Scenario A turned out to be correct. Dr. Hansen's forecast of future CO2 levels turned out to be excellent. That being the case, temperatures should followed the green (upper) line. Instead the actual temperatures have been colder than in any of his three scenarios, including C, which assumed falling CO2 levels!
So, while I cannot guess what Dr. Hansen had in mind when he said [he] "underestimated how bad things would get" the fact is the reverse is true. World temperatures are far, far below Hansen's forecast. FACT: In the real world, things are much cooler than Hansen forecast.
Dr. Hansen did make specific forecasts for Washington, D.C. in his 1988 paper. Here they are:
That said, Dr. Hansen is quoted in the article linking this summer's 23 days with 95° or hotter temperatures to global warming. Let's see how well this correlation actually works.
Below is Dr. Hansen's monthly world temperature data. I have highlighted the summers of 1980, 1988, 2008, 2009, and 2012.
In 1980, with significantly cooler world temperatures than today's, Washington, D.C. experienced 28 days of temperatures of 95° or higher -- five more than this summer. About the same number, 24, occurred in 1988 again with significantly cooler world temperatures.
In 2008, only 5 days (fewer than average) of 95 degrees temperatures occurred with world temperatures warmer than today's. In 2009, there were 8 days with temperatures about the same as today's
There is little or no correlation between Washington's summer temperatures and world temperatures.
If editors had known this, 430 of them might not have run with the story. This is the purpose of the the Friday press released timed for the Sunday papers with little opportunity for rebuttal.
This is "science by press release." Scientists with robust results are happy to go through the regular channels to release information.
Many times I have commented that the behavior of the pro-catastrophic global warming fringe is not consistent with people who are confident of their position. This is more of the same.
Addition: 9:40am Thursday August 9,
Two commenters (see below) quote excerpts of blog articles that are rationalizations of why Hansen's Scenario A forecast was so far off. While blogs can provide useful information, they misrepresent what is in Hansen's paper.
I prefer to consult Hansen's paper to learn what Hansen's paper says. It states (p. 9343),
"We define three trace gas scenarios to provide an indication of how the predicted climate trend depends on upon trace gas growth rates. Scenario A assumes that growth rates of trace gas emissions typical of the 1970's and 1980's will continue indefinitely; the assumed annual growth averages about 1.5% of current emissions, so the net greenhouse forcing increases exponentially. Scenario B has decreasing trace gas growth rates, such that the annual increase of the greenhouse climate forcing remains approximately constant at the present level. Scenario C drastically reduces trace gas growth between 1990 and 2000..."
Below is a graph of carbon dioxide concentrations since 1958. The rate of growth is the same now as it was in the 1970's and 1980s. Therefore, Scenario A applies.