I did not state that the models are not policy-relevant… both because I don’t agree with that being a binary statement of either they are or they aren’t (rather, they are useful for answering some questions and less useful for answering others), and because the specific issue I was responding to is not the most relevant factor in thinking through that question.
I disagree completely with your assertion that if we don’t correctly capture what the temperature would be in the year 3000, then it follows that our models are utterly useless for making near-term policy choices. Rather, I think that what happens in the next century or two actually do matter. I agree with you that what happens beyond then *also* matters, but I don’t think it is essential that a climate model correctly capture that. You don’t need to run a climate model to say that we’re in trouble if we maintain elevated CO2 concentrations for the next 1000 years, as this thread points out, and climate models aren’t necessarily useless simply because they ignore physics that isn’t (necessarily) relevant to predicting nearer-term impacts. And I do agree that the degree of uncertainty in heading into uncharted territory is not well understood, including the possibility of more rapid changes than are predicted in current climate models. But I think there’s a lot of room between “climate models are perfect representations of the future” and “climate models are not policy-relevant”; just because they are obviously not perfect does not make them totally useless as you seem to suggest… From: Robert Chris <[email protected]> Sent: Tuesday, April 11, 2023 8:23 AM To: Douglas MacMartin <[email protected]>; [email protected]; Tom Goreau <[email protected]> Cc: [email protected]; Planetary Restoration <[email protected]>; 'Eelco Rohling' via NOAC Meetings <[email protected]>; geoengineering <[email protected]> Subject: Re: [prag] Re: [geo] Are 1.5 c or 2.0 c thresholds economically realistic in a voluntary NDC regime? Doug It seems that mistakenly I thought you were justifying the appropriateness of the models. Apologies. On a closer reading, the following emerges: Your final words 'That isn’t what the models are intended to do', in context, mean that we shouldn't criticise the models for not being policy-relevant even though they exclude millennial factors because the models are not intended to be policy relevant. They are just models that produce certain outputs based on certain inputs and certain algorithms. The degree to which the models are a faithful predictor of the range of plausible futures is unknowable until that future arrives, and made more so by the absence of the millennial factors. Policymakers use these models at their (and our) peril. Have I got that right? If so, it might be a good idea if someone told the policymakers that they're basing their policies on the wrong data. Regards Robert On 11/04/2023 17:31, Douglas MacMartin wrote: Robert, I agree with almost everything you write, except for your belief that what you wrote is in any way in conflict with what I wrote. doug From: Robert Chris <[email protected]><mailto:[email protected]> Sent: Tuesday, April 11, 2023 3:17 AM To: Douglas MacMartin <[email protected]><mailto:[email protected]>; [email protected]<mailto:[email protected]>; Tom Goreau <[email protected]><mailto:[email protected]> Cc: [email protected]<mailto:[email protected]>; Planetary Restoration <[email protected]><mailto:[email protected]>; 'Eelco Rohling' via NOAC Meetings <[email protected]><mailto:[email protected]>; geoengineering <[email protected]><mailto:[email protected]> Subject: Re: [prag] Re: [geo] Are 1.5 c or 2.0 c thresholds economically realistic in a voluntary NDC regime? Doug There's a significant caveat in there - assuming we 'eventually get to net zero', and a significant ethical assumption - that policy relevance is limited to a century timescale. And a further physical climate assumption - that cascading tipping events will not be triggered on any plausible current and short term policy regime. If you set the rhetoric aside, there's little evidence to suggest that by mid-century or even for a decade or more after that, we'll get to net zero. Your 'eventually' is doing a lot of work here! For this to happen requires us to start the decommissioning of fossil fuel assets now and scaling GGR/CDR to close to or beyond GtCO2e/yr within the next few years. Current geopolitics shows no sign of substantive action to match the rhetoric on either of those, or the likelihood of any imminent breakthrough that might materially accelerate things. As to the ethical assumption, if the ethics are constrained to consider only the scenarios in which we get to net zero, then you need to be pretty damn sure you're going to get there. But we're far from being sure about that. So limiting policy relevance to the century timescale is tantamount to declaring that what happens beyond that is no concern of ours. This is like setting a discount rate that reaches infinity on 1 Jan 2100 (or maybe 2103) - all benefits and costs thereafter have no present value today so we don't need to worry ourselves about them. An ethics so constrained seems to me seriously dysfunctional. On the tipping events, the literature on this suggests that we are already treading on thin ice. Is it sane to base our policy regime on the assumption that there are no tipping points that might derail our smooth but slow transition to net zero? Regards Robert On 11/04/2023 01:07, Douglas MacMartin wrote: Also, of course, the long-term response is only realized if nobody ever develops and deploys any CDR over that long-term timeframe. If you believe that we will eventually get to net-zero and that some level of CDR will get deployed to go below net-zero, then it’s the century-scale warming that matters, not the millennial-scale. There are of course millennial-scale processes that are not included in climate models, so there’s neither any reason to expect them to match on that time-scale, nor any reason to criticize them on that particular basis, or to use that particular argument to suggest that the models aren’t policy-relevant. That isn’t what the models are intended to do. From: [email protected]<mailto:[email protected]> <[email protected]><mailto:[email protected]> On Behalf Of Michael MacCracken Sent: Monday, April 10, 2023 1:54 PM To: Tom Goreau <[email protected]><mailto:[email protected]>; Robert Chris <[email protected]><mailto:[email protected]> Cc: [email protected]<mailto:[email protected]>; Planetary Restoration <[email protected]><mailto:[email protected]>; 'Eelco Rohling' via NOAC Meetings <[email protected]><mailto:[email protected]>; geoengineering <[email protected]><mailto:[email protected]> Subject: Re: [prag] Re: [geo] Are 1.5 c or 2.0 c thresholds economically realistic in a voluntary NDC regime? Well, in that the climate depends on the radiative forcing and the radiative forcing is logarithmic with the CO2 concentration, doing a linear regression of CO2 and temperature would give an estimate of the rise in temperature that is far from linear, so the 16 C would be way too high. There is then the issue that the change in temperature in high latitudes is well above the global average change in temperature, and so that would be another contribution to giving a rate too high for the change in global average temperature. So, if regression were to get temperature change in high latitudes ad not the global average, one would have a value more than the change in the global average temperature. Mike On 4/10/23 1:29 PM, Tom Goreau wrote: It’s just the regression of Antarctic Ice temperature versus CO2 data. The sea level regression implies +23 meters. When I did it in 1990 there was only one glacial cycle of data, but Eelco Rohling independently did the same analysis when there was 800,000 years of data, and got essentially identical values. The models must be serious underestimates to fall so far off the actual long term climate data. Thomas J. F. Goreau, PhD President, Global Coral Reef Alliance Chief Scientist, Blue Regeneration SL President, Biorock Technology Inc. Technical Advisor, Blue Guardians Programme, SIDS DOCK 37 Pleasant Street, Cambridge, MA 02139 [email protected]<mailto:[email protected]> www.globalcoral.org<http://www.globalcoral.org> Skype: tomgoreau Tel: (1) 617-864-4226 (leave message) Books: Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase http://www.crcpress.com/product/isbn/9781466595392 Innovative Methods of Marine Ecosystem Restoration http://www.crcpress.com/product/isbn/9781466557734 No one can change the past, everybody can change the future It’s much later than we think, especially if we don’t think Those with their heads in the sand will see the light when global warming and sea level rise wash the beach away Geotherapy: Regenerating ecosystem services to reverse climate change From: Michael MacCracken <[email protected]><mailto:[email protected]> Date: Monday, April 10, 2023 at 4:23 PM To: Tom Goreau <[email protected]><mailto:[email protected]>, Robert Chris <[email protected]><mailto:[email protected]> Cc: "[email protected]"<mailto:[email protected]> <[email protected]><mailto:[email protected]>, Planetary Restoration <[email protected]><mailto:[email protected]>, 'Eelco Rohling' via NOAC Meetings <[email protected]><mailto:[email protected]>, geoengineering <[email protected]><mailto:[email protected]> Subject: Re: [prag] Re: [geo] Are 1.5 c or 2.0 c thresholds economically realistic in a voluntary NDC regime? Hi Tom--I'd be interested in seeing your 1990 paper because 16 C would take temperatures to much higher than they have ever been, and yet there have been periods when the CO2 concentration has apparently been well above 1000 ppm, so the 16 C value seems seriously inconsistent with what we know of Earth history. Best, Mike On 4/10/23 5:02 AM, Tom Goreau wrote: BEFORE UNFCCC was signed, it was clear from paleoclimate data that +16 degrees C or so is the equilibrium temperature for 400ppm CO2 (Goreau 1990), but all governments ignored the real data because they preferred the fictitious claim from models that warming would “only” be around 1-4 degrees C, and occur well after a new leader emerges from the next election, selection, or coup. I briefed the Association of Small Island States just before they signed on to a treaty that was an effective death sentence for low coasts and a suicide pact for low lying island nations to that effect, but their heads of states were told by the rich countries to sign or they would lose their foreign aid, something none could afford. They were effectively bought off to sacrifice their own people’s futures for worthless promises of financial support for adaptation that never came. No politician ever turns down money, no matter how insufficient. Instead what they got from the funding agencies was sea walls made from concrete and rock imported half way across the world, which have all fallen down due to erosion caused by wave reflection scouring. Their consultants keep promising that the next seawall, built to armor the ruins of previous seawalls, will last forever, it’s another shell game with peoples futures. Thomas J. F. Goreau, PhD President, Global Coral Reef Alliance Chief Scientist, Blue Regeneration SL President, Biorock Technology Inc. Technical Advisor, Blue Guardians Programme, SIDS DOCK 37 Pleasant Street, Cambridge, MA 02139 [email protected]<mailto:[email protected]> www.globalcoral.org<http://www.globalcoral.org> Skype: tomgoreau Tel: (1) 617-864-4226 (leave message) Books: Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase http://www.crcpress.com/product/isbn/9781466595392 Innovative Methods of Marine Ecosystem Restoration http://www.crcpress.com/product/isbn/9781466557734 No one can change the past, everybody can change the future It’s much later than we think, especially if we don’t think Those with their heads in the sand will see the light when global warming and sea level rise wash the beach away Geotherapy: Regenerating ecosystem services to reverse climate change From: Michael MacCracken <[email protected]><mailto:[email protected]> Date: Sunday, April 9, 2023 at 9:37 PM To: Tom Goreau <[email protected]><mailto:[email protected]>, Robert Chris <[email protected]><mailto:[email protected]> Cc: "[email protected]"<mailto:[email protected]> <[email protected]><mailto:[email protected]>, Planetary Restoration <[email protected]><mailto:[email protected]>, 'Eelco Rohling' via NOAC Meetings <[email protected]><mailto:[email protected]>, geoengineering <[email protected]><mailto:[email protected]> Subject: Re: [prag] Re: [geo] Are 1.5 c or 2.0 c thresholds economically realistic in a voluntary NDC regime? Hi Tom--Indeed, which is why I don't understand why the mainly island nation accepted, even insisted upon 1.5 C, as an aspirational goal. From paleoclimatic analysis, the equilibrium sensitivity for sea level rise is of order 15-20 METERS per degree C increase in the global average temperature. And how it is somehow justified that the curve shape for the sensitivity is a cubic and we are presently in the low sensitivity part of the curve does not at all seem justified to me (though perhaps the type of major ice sheet matters). I once asked the chief US negotiator (Todd Stern) at the Paris COP if they had viewed as a value that would be an upper limit and the subsequent goal and actions would be aimed at forcing the global average temperature back down, or if the vision was that actions would be taken to keep the increase in global average temperature to be 2 C and this would be an allowed long term value for the Earth. He indicated, as I recall, that what would happen after the value was reached was not discussed, they were so happy to have a number to consider an upper value they just never discussed the issue. Best, Mike On 4/9/23 7:40 AM, Tom Goreau wrote: The 1.5 degree “goal” like the 2.0 goal, is beyond the capacity of corals to adapt so it means the extinction of coral reef ecosystems, which already reached their high temperature tipping point in the mid 1980s. Coral reefs, and the species and people who live from them, have been consciously selected for sacrifice, rather than interrupting profits from fossil fuels. Coral reefs may be the first ecosystem to collapse, but they certainly won’t be the last! Thomas J. F. Goreau, PhD President, Global Coral Reef Alliance Chief Scientist, Blue Regeneration SL President, Biorock Technology Inc. Technical Advisor, Blue Guardians Programme, SIDS DOCK 37 Pleasant Street, Cambridge, MA 02139 [email protected]<mailto:[email protected]> www.globalcoral.org<http://www.globalcoral.org> Skype: tomgoreau Tel: (1) 617-864-4226 (leave message) Books: Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase http://www.crcpress.com/product/isbn/9781466595392 Innovative Methods of Marine Ecosystem Restoration http://www.crcpress.com/product/isbn/9781466557734 No one can change the past, everybody can change the future It’s much later than we think, especially if we don’t think Those with their heads in the sand will see the light when global warming and sea level rise wash the beach away Geotherapy: Regenerating ecosystem services to reverse climate change From: <[email protected]><mailto:[email protected]> on behalf of Robert Chris <[email protected]><mailto:[email protected]> Date: Sunday, April 9, 2023 at 10:35 AM To: Michael MacCracken <[email protected]><mailto:[email protected]> Cc: "[email protected]"<mailto:[email protected]> <[email protected]><mailto:[email protected]>, Planetary Restoration <[email protected]><mailto:[email protected]>, 'Eelco Rohling' via NOAC Meetings <[email protected]><mailto:[email protected]>, geoengineering <[email protected]><mailto:[email protected]> Subject: Re: Fwd: [prag] Re: [geo] Are 1.5 c or 2.0 c thresholds economically realistic in a voluntary NDC regime? Mike, you point to a key distinction that I had perhaps ignored. The dynamics of setting goals are not the same as those of realising them. Economics may have been a major factor in setting the Paris targets but they are not an enabler of their realisation. If the political will was there among a sufficient number of leading economies to deliver on the Paris targets, they would find a way of doing that that would overcome any economic constraints that might otherwise have been thought to be impediments. Regards Robert As I loosely recall, when the 2 C goal was approved in Paris, the value was chosen because it was thought that it would be realistically/economically achievable. The goal could not be higher due to thoughts about tipping points or lower due to economic realities--though they did set 1.5 C as an aspirational goal as the developing nations felt the impacts of 2 C on them would be unbearable. So, I'd say economics played a goal there--indeed, even the primary rationale for the choice. Mike On 4/8/23 9:54 AM, Robert Chris wrote: > David, you've put your finger right on it. Being economically > realistic is not a sufficient condition to enable the realisation of > any goal. For some goals, it isn't even a constraint because for > them, what is economically realistic is made to fit the goal, rather > than the goal being tailored to fit what's economically realistic. > Money is not the only store of value. > > Regards > > Robert > > > On 08/04/2023 18:26, David desJardins wrote: >> If the goal is always economically realistic, then it follows that >> looking at the goal through an economic lens will always enable it, >> not prevent it. > -- You received this message because you are subscribed to the Google Groups "Healthy Planet Action Coalition (HPAC)" group. 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