Above, I interviewed a number of the most senior climate scientists for this Yale piece, I believe on the 30th anniversary of James Hansen’s 1988 Senate Testimony, where he announced that the signal of human caused climate change had been detected.
How have his projections held up? Pretty well as of 2018.
More recent graph of global temps vs model predictions below, current as of March of this year.
Dana Nuccitelli in the Guardian, June 2018:
The incredible accuracy of Hansen’s climate model predictions debunks a number of climate denier myths. It shows that climate models are accurate and reliable, that global warming is proceeding as climate scientists predicted, and thus that we should probably start listening to them and take action to address the existential threat it poses.
Hansen’s predictions have thus become a target of climate denier misinformation. It began way back in 1998, when the Cato Institute’s Patrick Michaels – who has admitted that something like 40% of his salary comes from the fossil fuel industry – arguably committed perjury in testimony to Congress. Invited by Republicans to testify as the Kyoto Protocol climate agreement was in the works, Michaels was asked to evaluate how Hansen’s predictions were faring 10 years later.
In his presentation, Michaels deleted Hansen’s Scenarios B and C – the ones closest to reality – and only showed Scenario A to make it seem as though Hansen had drastically over-predicted global warming. Deleting inconvenient data in order to fool his audience became a habit for Patrick Michaels, who quickly earned a reputation of dishonesty in the climate science world, but has nevertheless remained a favorite of oil industry and conservative media.
Last week in the Wall Street Journal, Michaels was joined by Ryan Maue in an op-ed that again grossly distorted Hansen’s 1988 paper. Maue is a young scientist with a contrarian streak who’s published some serious research on hurricanes, but since joining the Cato Institute last year, seems to have sold off his remaining credibility to the fossil fuel industry.
In their WSJ opinion piece, Michaels and Maue claimed:
Global surface temperature has not increased significantly since 2000, discounting the larger-than-usual El Niño of 2015-16. Assessed by Mr. Hansen’s model, surface temperatures are behaving as if we had capped 18 years ago the carbon-dioxide emissions responsible for the enhanced greenhouse effect.
They provided no evidence to support this claim (evidence and facts seem not to be allowed on the WSJ Opinion page), and it takes just 30 seconds to fact check. In reality, global surface temperatures have increased by about 0.35°C since 2000 – precisely in line with Hansen’s 1988 model projections, as shown above. And it’s unscientific to simply “discount” the El Niño of 2015-16, because between the years 1999 and 2014, seven were cooled by La Niña events while just four experienced an El Niño warming. Yet despite the preponderance of La Niña events, global surface temperatures still warmed 0.15°C during that time. There’s simply not an ounce of truth to Michaels’ and Maue’s central WSJ claim.
The first transient climate projections using GCMs are 30 years old this year, and they have stood up remarkably well.
We’ve looked at the skill in the Hansen et al (1988) (pdf) simulations before (back in 2008), and we said at the time that the simulations were skillful and that differences from observations would be clearer with a decade or two’s more data. Well, another decade has passed!
UPDATE:
In ’88, Hansen postulated a (then imaginary) volcanic eruption in the early 90s. A key indicator of the skill of his model occurred when Mt Pinatubo conveniently erupted very close to that point on the timeline, and the following global temperature response was a neat confirmation of Hansen’s graph.
I made a video on this some years ago.
Brilliant educational video – short, digestible and informative and hopefully convincing.