Today I learned (day 2 of AGU) some good news.

It was quite a firehose.

Let me start by suggesting that I am not now doing anything like “climate advocacy” here. If that is what you came for, you are in the wrong place.

Here is what I mean: We Need Facts More Than Ever

A trustworthy source publishes correct and salient information regardless of which tribe it benefits.

There’s not much trust to go around, and it always hurts to get the “shill” word thrown in your face and lose half your readers by violating their tribal assumptions. If you’re still reading, by now, I guess you aren’t one of those.

So today I learned something that will give aid and succor to the lukewarmers and a bludgeon for the deniers. There’s strong evidence emerging that the model transient response is too fast – an at least one case a very high resolution very credible version of a scalable model shows that for a given CO2 trajectory. That is, there’s new evidence that shows the world is probably going to warm more slowly than the models have heretofore suggested (for the same emissions scenario).

This is basically good news and I needed some.

There are important caveats. Single study syndrome of course. This needs replication in other models. That will come eventually.

1) This tells us nothing about the equilibrium climate sensitivity. Nothing at all. I worry that most people will not understand this.

2) This doesn’t mean anything is wrong with radiative transfer theory. It means that the subsurface ocean is going to take up more of the heat imbalance than the coarser models heretofore possible were able to represent.

3) The main actual warm anomaly is at the Antarctic margin. Without talking to experts on this, I find myself speculating that, far from easing the sea level rise problem, it will make it worse by softening the WAIS.

But on the whole, to the extent that the story is “global warming”, it is good news. It is certainly good news for people in hot, humid climates (e.g. Texas) in that the worst may be slower in arriving.

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Also in a pair of separate conversations I got quite an earful about the prospects for a market-driven renewable energy future. Both were very convincing. One was very enthusiastic and the other very skeptical. Both live in the Bay Area. I wonder if I should introduce them.

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I went to a climate dynamics session, a climate modeling session, and an ecological impacts session. I was enormously impressed by some of the talks, especially at the first two sessions.

One talk described immense statistical contortions and went clear over my head. (This is, frankly, not that common.) But then when the speaker got to the final conclusion, it was essentially a tiny correlation between extreme rainfall events in a few very particular places with particular large scale atmospheric flows upstream. It looked like noise to me.

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Comments:

  1. Wow - 1/3 less than current models? If the finding holds, does this suggest that warming at a level (say 450ppm) is delayed many decades from current models? That would mean docs like this need radical fixes, as the high side in this one (2015) includes possibility of 4C by 2060
    http://tyndall.ac.uk/sites/default/files/twp162_0.pdf …

    on p. 5 "Work by scientists involved in the HELIX project suggests that the likelihood of high levels
    of warming and greater extremes, potentially occurring sooner than previously thought – e.g.
    3°C in the 2040s (Jackson et al. 2015), 4°C rise in 2060s (Betts et al. 2011)"

  2. This doesn't make much sense to this non-climate-scientist. Any chance of a version targeted at folks like me? It'd be good to know why you think / others might think this one study is important enough to alter your priors so much (seems like a big thing to do just from one presentation?) rather than being just that - one study in a huge field that, until there's been a bunch of further work, is on probation?

  3. It's definitely on probation. But I'd say it has a very strong epistemic case, because it compares two versions of the same model, one with a high enough resolution that there is little precedent. There are other reasons to judge the high resolution model reliable.

    What's more, the GMST trajectory it comes up with is actually closer to what we are seeing.

    And as I said, not entirely good news. Would like to know sea level implications. But Vecchi is not studying WAIS, and again, this was an unanticipated and unlooked-for result, not the payload of his study.

    Payload of his study was tropical storms, and yes, they get fiercer under climate change.


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