Climate scientist Professor Kevin Anderson weighed in on the debate on whether the recent warming is beyond what the models predict, pointing out that “it’s not just the scale of change, it’s the timeline of that scale of change. And that’s the real difference between Hansen and Mann. Really, it is one of timeline. They both end up being in a terrible place. The Hansen analysis gets us there a little sooner than that of Mann, but in the absence of deep and rapid cuts in emissions both are going to get there.”
Interviewed before making a presentation at a January 30th public meeting in Glossop, England, Anderson was asked about the “Team Mann versus Team Hansen” debate (this was before Hansen et al.’s paper Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed? was published)
I see a lot of good reasons to be taking more notice of the Hansen end of the spectrum. But as with all science, there’s a range of uncertainty that comes out of equally robust analysis. So Mann’s analysis could be correct, and so could Hansen’s, and we can’t, we can’t know which of those are more accurate until we get an improved understanding and more empirical data.
But does that affect our policy framework? No, not really. Risk is an important part of policy, risk and uncertainty. So we should start planning for the repercussions of the Hansen end of the spectrum being correct. The consequences of Mann analysis are pretty disastrous anyway, but Hansen’s conclusions land more within a dire to catastrophic framing. And from a responsible political perspective, I think we have to lean our policies more towards the worst case than hoping for more optimistic interpretations to play in our favour.
As it is today policy makers fail to have the courage or clarity of vision to even grapple with the Mann end of the spectrum. To put it bluntly, at both the global and national level the policy realm embeds a soft form of denial.
The interview covered a range of topics, and will be released in portions. You can read the first part here. It was conducted by Dr Marc Hudson, who has interviewed Professor Anderson on several occasions over the past 15 years. Dr Hudson runs All Our Yesterdays, an “on this day” website about climate politics, technology, protest that covered events from 1661 to the present day.
The transcript of the relevant portion of the interview can be found below.
You are free (and of course encouraged) to use this material for commercial or non-commercial purposes. Please cite both the source (i.e. that the interview was conducted by Marc Hudson, and the URL of this page.
Give me the conch back. Two observations and the next question. Observation one is in the 60s and 70s, or early 70s, it was this toss up between, “are we going to freeze or are we going to burn?” Obviously, the science has come on a very long way, but we’re kind of still in the same place and interesting.
And then I’m reminded of the late, great Wally Broecker, the oceanographer, who said of ocean currents and climate, that we were poking the beast with a sharp stick, and there might be trouble if we woke the beast up. I think the beast is snuffling. And in that pre awake, yes, pre awake phase,
OK. Next question. So here’s my rough characterization. There is “Team Michael Mann” that says, you know “the temperature anomalies of 2023 24 while surprising, are within what the models kind of suggest and expect and quote.‘The truth is bad enough.’” And then there is “Team Hansen with people like James Hansen, Leon Simons, saying, “no, no. no no The lessening of the sulfates from the marine pollution and other factors means that the models that we have been using, including the IPCC, are no longer adequate.”
And even Gavin Schmidt, they would say, is having to admit that he’s confused [Guardian]. And you know, Gavin Schmidt is kind of at the smart end, shall we say, of climate scientists.
So where is Kevin Anderson? Is he firmly in the camp of … First is this a fair characterization of the debates that are happening among the scientists? Or is it. unfair? And second question is, where does Kevin Anderson fit? Is he Team Mann or Team Hansen, or is he a substitute, or is he playing a different game altogether?
Kevin Anderson 10:14
I see a lot of good reasons to be taking more notice of the Hansen end of the spectrum. But as with all science, there’s a range of uncertainty that comes out of equally robust analysis. So Mann’s analysis could be correct, and so could Hansen’s, and we can’t know which of those are more accurate until we get an improved understanding and more empirical data.
But does that affect our policy framework? No, not really. Risk is an important part of policy, risk and uncertainty. So we should start planning for the repercussions of the Hansen end of the spectrum being correct. The consequences of Mann analysis are pretty disastrous anyway, but Hansen’s conclusions land more within a dire to catastrophic framing. And from a responsible political perspective, I think we have to lean our policies more towards the worst case than hoping for more optimistic interpretations to play in our favour.
As it is today policy makers fail to have the courage or clarity of vision to even grapple with the Mann end of the spectrum. To put it bluntly, at both the global and national level the policy realm embeds a soft form of denial. There’s an acceptance of the science, but a denial of the need to act accordingly; behind the eloquence and rhetoric, fingers remain firmly crossed that we’ll somehow be ok.
marc hudson 11:48
Don’t talk about the airport expansion. That’s my next question.
Kevin Anderson 11:52
Is it. Okay.
Thinking about how we, the academic and wilder climate expert realm, engage with policy makers, I see it incumbent on us to start by asking what does the policy landscape look like if we’re to deliver the deep cuts in emissions needed in a climate emergency? But also, of course, how on earth do we adapt? How do we, and the ‘we’ is important in this, adapt to the scale of change that is implied by the Hansen framing of these issues?”
And it’s not just the scale of change, it’s the timeline of that scale of change. And that’s the real difference between Hansen and Mann. Really, it is one of timeline. They both end up being in a terrible place. The Hansen analysis gets us there a little sooner than that of Mann, but in the absence of deep and rapid cuts in emissions both are going to get there.
marc hudson 12:44
We’ve had these warnings since 1988 in public,
Yep
and from scientists since late 70s. I think it’s fair to say
Yep
though you can, you can heckle me when I’m doing my presentation, because I cover this though. The omens – if past performance is the best indicator of future performance – the omens are not good.
For more of Kevin’s work see climateuncensored.com
Tomorrow’s blog post – UK aviation emissions and the proposed Third Runway at Heathrow.
Additional info: Team Mann versus Team Hansen
Anderson, K. 2025 Has Global Warming Accelerated – a short response to Hansen et al
also just published –
Cheng, L., Abraham, J., Trenberth, K.E. et al. Record High Temperatures in the Ocean in 2024. Adv. Atmos. Sci. (2025). https://doi.org/10.1007/s00376-025-4541-3