That’s a serious citation needed – and since my experience with science deniers started creationists I expect that to be an original source with context, not the inaccurate summary given by the person you actually read.

Here’s an example something verifiable, from his Senate testimony in 1988 as covered by the Washington Post:

> "The greenhouse effect has been detected and it is changing our climate now," Hansen testified at a hearing of the Senate Committee on Energy and Natural Resources. "We already reached the point where the greenhouse effect is important."

> Although scientists have previously theorized about the greenhouse effect and issued vague projections of rising temperatures sometime in the next century, Hansen is the first to concretely link warming and greenhouse gases and to authoritatively proclaim the phenomenon's arrival.

> He warned, moreover, of an "increasing tendency" for droughts and heat waves, especially in the Southeast and Midwest, during the balance of this decade and the 1990s.

https://www.washingtonpost.com/archive/politics/1988/06/24/s...

(Historical review: https://yaleclimateconnections.org/2018/06/judgment-on-hanse...)

Now, this isn’t the first time I’ve heard that particular story so I’ll help you out: it’s a misstatement made by someone else (Bob Reiss) when talking to a Salon.com reporter thirteen years later in 2001, and the original question was a speculative off-the-cuff prediction about the impacts of CO2 levels doubling, which fortunately has not happened yet:

> Michaels also has the facts wrong about a 1988 interview of me by Bob Reiss, in which Reiss asked me to speculate on changes that might happen in New York City in 40 years assuming CO2 doubled in amount. Michaels has it as 20 years, not 40 years, with no mention of doubled CO2. Reiss verified this fact to me, but he later sent the
message: "I went back to my book and re-read the interview I had with you. I am embarrassed to say that although the book text is correct, in remembering our original conversation, during a casual phone interview with a Salon magazine reporter in 2001 I was off in years. What I asked you originally at your office window was for a prediction of what Broadway would look like in 40 years, not 20. But when I spoke to the Salon reporter 10 years later - probably because I'd been watching the predictions come true, I remembered it as a 20 year question." So give Michaels a pass on this one -- assume that he reads Salon, but he did not check the original source, Reiss' book.

Source: http://www.columbia.edu/%7Ejeh1/mailings/2011/20110126_Singi...

More importantly, one man is not an entire scientific field. When talking about accuracy, we should be looking at the IPCC reports since those have a multi-decade history we can compare to actual measures change by now:

https://arstechnica.com/science/2012/12/ipccs-climate-projec...

https://www.vox.com/energy-and-environment/2019/12/4/2099131...

What’s also interesting is to see how the various lies funded by the fossil fuel industry have fared over that same time. Like the tobacco industry science deniers – in some cases the same people – they haven’t shown any track record of accuracy, flitting around from detail to detail trying to say that any unusual point on a graph disproves the entire field. We’ve heard various cases of wishful thinking around sunspots, satellite error, buoy error, urban vs. rural discrepancies, etc. and the common thread is that none of those have held up scientifically or meaningfully changed the trajectory. That’s the difference between scientists who are critically examining their own work and corporate lobbyists who are starting with the conclusion that their profit margins shouldn’t change and working backwards.