OK, we have a problem.

I just finished reading through the second part of the GISS-E climate modelling paper. I’ll write a summary later, either a technical one for or a non-technical one for here, but that’s going to take a while, and this is important.

Everyone, you need to read this document carefully, specifically sections 6-8, including the figures. Those sections require not much more than knowing what a standard deviation is and that a “climate forcing” means “any input to the ecosystem that can affect climate.” The first five sections, short version, say that the model has proven pretty good at predicting global-scale climate change for 1880-2003, it’s not as good at predicting regional change, and its main weaknesses are an ocean model that doesn’t understand El Niño and a sea ice model that nobody really trusts. My professional opinion is that it’s definitely good enough to rely on its numbers for global-scale analyses, but it may underestimate ice melting. (And the authors freely admit the latter)

Sections 6-8 talk about their models for the period 2003-2100, according to five models: “alternative”, “2C”, and three from the Intl Panel on Climate Change.

I know this is a bit of a technical thing to be asking people to read, but this is probably the most important thing that’s crossed my desk in years, and we need to start planning urgently. Pay particular attention to figures 19, 20 and 22.

Ladies and gentlemen, we have a problem. This outweighs anything on the political arena short of global thermonuclear war. I don’t think I could summarize what IPCC scenario A2 would look like by 2100 and have you believe me; but I would say that that scenario implies a real chance of a major population collapse, up to and including extinction and certainly impacting the viability of civilization.

The good news is, the two best scenarios (Alt and 2C) would leave us coming out fairly OK, and both of those are reachable with modern technology and not too much trouble; getting from here to there seems to require policy changes rather than anything enormously terrifying. The figures in the paper describe what emissions goals we would have to hit.

I’ll write up a more detailed summary later, and try to pull the key information out of this document.

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Published in: on May 10, 2006 at 18:40  Comments (18)  
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18 Comments

  1. I hate to admit it, but geologists have been saying this for years, and the govt wasn’t listening. I actually just heard a talk by Michael Mann, one of the scientists who developed the model that produced the now-famous “hockey stick” diagram, showing the huge increase in northern hemisphere mean temperature. He was on the IPCC and this figure was included. In his talk he also stressed that we need to understand the influence of El Nino and La Nina because they have been shown to affect — if not global temperature — global climate. *Very* interesting talk.

  2. I hate to admit it, but geologists have been saying this for years, and the govt wasn’t listening. I actually just heard a talk by Michael Mann, one of the scientists who developed the model that produced the now-famous “hockey stick” diagram, showing the huge increase in northern hemisphere mean temperature. He was on the IPCC and this figure was included. In his talk he also stressed that we need to understand the influence of El Nino and La Nina because they have been shown to affect — if not global temperature — global climate. *Very* interesting talk.

  3. I know they’ve been saying it; now, I’m just hoping someone will listen.
    One thing I noticed from the model is that for 1880-2003 they ran with both an experimentally-derived ocean and with two different models (Q-flux and Russell). The models seemed to capture overall global means pretty well, even the change post-Pinatubo, although they weren’t as good at getting regional temperatures right.

  4. I know they’ve been saying it; now, I’m just hoping someone will listen.
    One thing I noticed from the model is that for 1880-2003 they ran with both an experimentally-derived ocean and with two different models (Q-flux and Russell). The models seemed to capture overall global means pretty well, even the change post-Pinatubo, although they weren’t as good at getting regional temperatures right.

  5. I’d be caught up, except that i got diverted into the efficacy paper. I wanted some clue exactly how their model functioned before digging in further. It’s mostly a sanity check, to ensure i’m not missing any big pieces of background before trying to comprehend everything. So far, so good.
    The problem(s?) they have with sea ice and polar temperature predictions is particularly bothersome to me, since this contributes so strongly to the doomsday problems everyone predicts.
    (Also a factor in my slowness: my brain-time lately goes to toy indexing and, uh, video games, sorry to say.)

  6. I’d be caught up, except that i got diverted into the efficacy paper. I wanted some clue exactly how their model functioned before digging in further. It’s mostly a sanity check, to ensure i’m not missing any big pieces of background before trying to comprehend everything. So far, so good.
    The problem(s?) they have with sea ice and polar temperature predictions is particularly bothersome to me, since this contributes so strongly to the doomsday problems everyone predicts.
    (Also a factor in my slowness: my brain-time lately goes to toy indexing and, uh, video games, sorry to say.)

  7. It looks like not all of the problems are polar; in the 2100 surface temperature predictions, there seemed to be a pretty broad global distribution of trouble in the worse scenarios. (Which may mean that the various scenarios are missing even bigger polar trouble, of course)
    And my brain-time lately goes to indexing as well, so no prob. 🙂

  8. It looks like not all of the problems are polar; in the 2100 surface temperature predictions, there seemed to be a pretty broad global distribution of trouble in the worse scenarios. (Which may mean that the various scenarios are missing even bigger polar trouble, of course)
    And my brain-time lately goes to indexing as well, so no prob. 🙂

  9. um… eeek?
    Yeah, I’ll be reading this, but prolly not before the weekend. I’ll have Aleatha-girl remind me, too. Workstuff and housetuff piling up.

  10. um… eeek?
    Yeah, I’ll be reading this, but prolly not before the weekend. I’ll have Aleatha-girl remind me, too. Workstuff and housetuff piling up.

  11. One thing they’ve been doing is evolving the models, each time adding another perturbation and making it more complex. So they’ve recently figured out how to model the effect of large tropical volcanic eruptions. Extra-tropical ones I don’t know about.

  12. One thing they’ve been doing is evolving the models, each time adding another perturbation and making it more complex. So they’ve recently figured out how to model the effect of large tropical volcanic eruptions. Extra-tropical ones I don’t know about.

  13. Yes. ENSO is definitely next on the list, but I really would like to see some more work on ice melting, especially on wet processes. The sigmas for the model are simply way too high for my taste at the poles.

  14. Yes. ENSO is definitely next on the list, but I really would like to see some more work on ice melting, especially on wet processes. The sigmas for the model are simply way too high for my taste at the poles.

  15. Thanks for doing this work. I’ve been really preoccupied as of late, but I’m keeping tabs on your progress with this.

  16. Thanks for doing this work. I’ve been really preoccupied as of late, but I’m keeping tabs on your progress with this.

  17. Thanks for starting the ball rolling, Y. I still haven’t dug into this, but I commit to reading it by next weekend at the latest (I’ll be on a low-key vacation and have plenty of time for reading).

  18. Thanks for starting the ball rolling, Y. I still haven’t dug into this, but I commit to reading it by next weekend at the latest (I’ll be on a low-key vacation and have plenty of time for reading).


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