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The authors don't include some extremely nasty feedback loops the appear to currently be happening. For example, methane release from permafrost melt. As a res

The authors don't include some extremely nasty feedback loops the appear to currently be happening. For example, methane release from permafrost melt. As a result, the simulation appears to be misleadingly optimistic. - This tool is based on climate interactive's previous one, C-Road. - in the C-Road simulation when you click on parameters -> assumptions to add parameters about methane release through permafrost melting and human activities. By default, it's set to zero, but even their maximum values don't seem as impactful as I would expect. - in EN-Road simulation (this one) the methane release parameters are removed! So, no possibility to add any positive feedback loops. It feels like the relation between CO2 and temperature is a simple linear equation, or close to it.

koheripbal 7y ago
While negative feedback loops are big in the media, they are not well understood and difficult to model. Also, other feedback mechanisms seem to get little attention. Are we only looking to model the feedback mechanisms that reinforce a narrative of cataclysm? Don't other feedback mechanisms exist that lessen CO2 concentrations, or temperature dissipation?
- breakyerself 7y ago
  No. They aren't "only looking at feedback mechanisms that reinforce cataclysm." Modelers include every feedback that they can quantify well enough to include and the ones they don't understand well enough are studied carefully to be able to work out what the uncertainties are. Scientists 50 years ago predicted that we would be at around 1C (1.8F) of warming by 2020 with a 40% over preindustrial co2 level. That's exactly what we have now. They predicted almost perfectly today's climate decades before it came to pass. That may not seem like a big deal until you understand that global temperatures haven't been this high in 130,000 years. It isn't being recognized properly yet in the media, but the stunning accuracy of predictions by climate modelers is one of the greatest achievements in the history Earth sciences.
  - mistermann 7y ago
    This sounds like you're saying that 50 years ago there was a single climate model, upon which significant consensus among scientists had been reached, that predicted a 1C temperature rise. I've read quite a few articles and discussions on this topic but have never heard this before. Am I misunderstanding you? If not, do you have a link that discusses this?
    - phaemon 7y ago
      Perhaps the Sawyer paper from 1973? https://www.carbonbrief.org/analysis-how-well-have-climate-models-projected-global-warming https://www.carbonbrief.org/analysis-how-well-have-climate-m...
      - mistermann 7y ago
        Surely there was one model that happened to come up with the right prediction, I would assume there were multiple. But my questions is whether there was one model with consensus support (which seems to be the claim), which would be necessary to rule out survivorship bias.
        phaemon 7y ago
        > Surely there was one model that happened to come up with the right prediction What does that mean? This "model" is someone sitting down and, using what we know of physics, calculating how something will warm up when you add some extra energy (in this case, the earth). You surely don't think that physics works by people randomly guessing answers and then one of them "happened" to be correct? You don't, do you?!
        rbavocadotree 7y ago
        From the 1975 US National Academy of Sciences/National Research Council Report ...we do not have a good quantitative understanding of our climate machine and what determines its course. Without the fundamental understanding, it does not seem possible to predict climate... [0] The point is that there were a lot of climate models done in the 70's, and only a few of them were accurate. No one was randomly guessing, but the model you gave was not the consensus. [0] https://skepticalscience.com/ice-age-predictions-in-1970s-intermediate.htm https://skepticalscience.com/ice-age-predictions-in-1970s-in...
- CalRobert 7y ago
  "While negative feedback loops are big in the media" You mean positive, right? As in self-reinforcing? Negative would mean the opposite, and there are a few of them (greater plant growth etc.) but they seem to be more than cancelled out by the positive (bad) feedback loops.
- jellicle 7y ago
  If they did exist, we would take their effects as baseline assumptions and just ratchet down our opinion about the crisis, if that makes sense. To the extent there are buffers, we just assume their effects, and we'll be unpleasantly surprised when the buffers run out. Examples: in the 70s we had a great deal of particulate smog, which effectively reduced some of the radiation hitting the Earth and camouflaged the effects of global warming. But instead of saying "hey, global warming must be a big problem since we're noticing X amount of warming EVEN WITH PARTICULATE SMOG", it just let us ignore global warming for longer. Example: the deep oceans have been an effective heat sink and some amount of the global heat has gone into them. Again, instead of saying "global warming must be a big problem since we're noticing X amount of land warming EVEN THOUGH THERE'S A GIANT HEAT SINK", it just let us ignore global warming for longer. So, to the extent that there are any buffers, we'll just build them into our baseline of "how bad the problem is", and therefore ALL of our surprises and feedback effects will be seen to be negative.

koheripbal 7y ago

While negative feedback loops are big in the media, they are not well understood and difficult to model. Also, other feedback mechanisms seem to get little attention. Are we only looking to model the feedback mechanisms that reinforce a narrative of cataclysm? Don't other feedback mechanisms exist that lessen CO2 concentrations, or temperature dissipation?

breakyerself 7y ago
No. They aren't "only looking at feedback mechanisms that reinforce cataclysm." Modelers include every feedback that they can quantify well enough to include and the ones they don't understand well enough are studied carefully to be able to work out what the uncertainties are. Scientists 50 years ago predicted that we would be at around 1C (1.8F) of warming by 2020 with a 40% over preindustrial co2 level. That's exactly what we have now. They predicted almost perfectly today's climate decades before it came to pass. That may not seem like a big deal until you understand that global temperatures haven't been this high in 130,000 years. It isn't being recognized properly yet in the media, but the stunning accuracy of predictions by climate modelers is one of the greatest achievements in the history Earth sciences.
- mistermann 7y ago
  This sounds like you're saying that 50 years ago there was a single climate model, upon which significant consensus among scientists had been reached, that predicted a 1C temperature rise. I've read quite a few articles and discussions on this topic but have never heard this before. Am I misunderstanding you? If not, do you have a link that discusses this?
  - phaemon 7y ago
    Perhaps the Sawyer paper from 1973? https://www.carbonbrief.org/analysis-how-well-have-climate-models-projected-global-warming https://www.carbonbrief.org/analysis-how-well-have-climate-m...
    - mistermann 7y ago
      Surely there was one model that happened to come up with the right prediction, I would assume there were multiple. But my questions is whether there was one model with consensus support (which seems to be the claim), which would be necessary to rule out survivorship bias.
      - phaemon 7y ago
        > Surely there was one model that happened to come up with the right prediction What does that mean? This "model" is someone sitting down and, using what we know of physics, calculating how something will warm up when you add some extra energy (in this case, the earth). You surely don't think that physics works by people randomly guessing answers and then one of them "happened" to be correct? You don't, do you?!
        rbavocadotree 7y ago
        From the 1975 US National Academy of Sciences/National Research Council Report ...we do not have a good quantitative understanding of our climate machine and what determines its course. Without the fundamental understanding, it does not seem possible to predict climate... [0] The point is that there were a lot of climate models done in the 70's, and only a few of them were accurate. No one was randomly guessing, but the model you gave was not the consensus. [0] https://skepticalscience.com/ice-age-predictions-in-1970s-intermediate.htm https://skepticalscience.com/ice-age-predictions-in-1970s-in...
CalRobert 7y ago
"While negative feedback loops are big in the media" You mean positive, right? As in self-reinforcing? Negative would mean the opposite, and there are a few of them (greater plant growth etc.) but they seem to be more than cancelled out by the positive (bad) feedback loops.
jellicle 7y ago
If they did exist, we would take their effects as baseline assumptions and just ratchet down our opinion about the crisis, if that makes sense. To the extent there are buffers, we just assume their effects, and we'll be unpleasantly surprised when the buffers run out. Examples: in the 70s we had a great deal of particulate smog, which effectively reduced some of the radiation hitting the Earth and camouflaged the effects of global warming. But instead of saying "hey, global warming must be a big problem since we're noticing X amount of warming EVEN WITH PARTICULATE SMOG", it just let us ignore global warming for longer. Example: the deep oceans have been an effective heat sink and some amount of the global heat has gone into them. Again, instead of saying "global warming must be a big problem since we're noticing X amount of land warming EVEN THOUGH THERE'S A GIANT HEAT SINK", it just let us ignore global warming for longer. So, to the extent that there are any buffers, we'll just build them into our baseline of "how bad the problem is", and therefore ALL of our surprises and feedback effects will be seen to be negative.