Peter,

Thank you for the question.

Sometimes political provocations are important to stimulate public action
(as I expect you well know!).  I also believe that Make Sunsets could morph
into a useful and effective private direct climate cooling initiative,
either within a carefully publicly regulated SAI regime, or using some
other "cloud making" method.

As I said none of us has a crystal ball but we need to support all possible
methods and systems (including ownership and institutional within existing
economic frameworks)  to move cooling forward.

Time is fleeting as I probably don't need to remind anyone on these lists!

Best,
Ron



On Thu, Mar 2, 2023 at 3:42 PM Peter Fiekowsky <[email protected]> wrote:

> Ron-
>
> Pardon me for asking, but:
>
>    1. What exactly do you mean by “all hands on deck”? Who? Where? Why?
>    When?
>    2. If you were successful, what outcome would we see?
>
>
>
> Nevermind the how. We know a heck of a lot about SAI, MCB, and other
> techniques. Please explain the who, what, when, where, and why for your
> call to action.
>
>
>
> Again, I apologize for asking—it must be annoying.  I hope you agree that
> getting this clarity is the only way success is possible.
>
>
>
> Peter
>
>
>
> *From: *[email protected] <
> [email protected]> on behalf of Ron Baiman <
> [email protected]>
> *Date: *Thursday, March 2, 2023 at 12:01 PM
> *To: *[email protected] <[email protected]>
> *Cc: *Ye Tao <[email protected]>, Tom Goreau <[email protected]>,
> Robert Chris <[email protected]>, Douglas Grandt <
> [email protected]>, peter jenkins <[email protected]>,
> 'Eelco Rohling' via NOAC Meetings <[email protected]>,
> Healthy Climate Alliance <[email protected]>,
> Planetary Restoration <[email protected]>,
> geoengineering <[email protected]>,
> healthy-planet-action-coalition <
> [email protected]>
> *Subject: *[HCA-list] Re: Make Sunsets stimulates more debate over
> "Geoengineering"- PT Barnum further vindicated!
>
> Thank you Robert, Achim and Paul,
>
>
>
> Needless to say, I agree. As expressed in my Make Sunsets blog, I believe
> that we need “all hands on deck” on cooling. Public, private, non-profit
> initiatives all have I think have different strengths that can help move
> direct climate cooling forward at speed and scope as with CDR and emissions
> reduction.
>
>
>
> On the cooling credits issue, as I’ve noted in earlier threads, its a bit
> more complicated than GHG credits as, depending on method, cooling is not
> generally a pure public good as GHG reduction is. Where, how, and how much
> is done makes more of a difference. And (as I believe we all agree) there
> are major risk issues for (effective) high leverage cooling initiatives
> that need to be carefully studied, monitored and adjusted for gradual ramp
> up (or down) that clearly require public implementation or very stringent
> public monitoring and regulation.
>
>
>
>   But in my view, for now politically provocative private initiatives
> (that don’t cause any physical harm) like Make Sunsets can be helpful, and
> carbon credits allow for larger groups of citizens/customers to make their
> voices heard that direct climate cooling needs to be Implemented now!
>
>
>
> Best,
>
> Ron
>
>
>
> Sent from my iPhone
>
>
>
> On Mar 2, 2023, at 4:05 AM, [email protected] wrote:
>
> 
>
> Ron
>
>
>
> We had some discussion on Radiative Forcing Credits at
> https://groups.google.com/g/planetary-restoration/c/02nphUdUtjU.  This
> thread includes a link to the ISO 2019 Draft Document ISO/NP 14082
>
> GHG management – Guidance for the quantification and reporting of
> radiative forcing based climate footprints and mitigation efforts.  This
> was intended to develop a Standard on Radiative Forcing, but was abandoned.
>
>
>
> My discussion note
> https://planetaryrestoration.net/f/radiative-forcing-credits explores
> some broad parameters for pricing cooling credits.
>
>
>
> I was surprised the recent letter supporting SRM Research from 60
> scientists <https://climate-intervention-research-letter.org/> claimed
> that SRM “likely will never be an appropriate candidate for an open market
> system of credits”.  I disagree with this assertion.  I have not seen any
> scientific or economic literature to back up this claim, which looks like a
> political reaction to Making Sunsets.
>
>
>
> Regards
>
>
>
> Robert Tulip
>
>
>
> *From:* [email protected] <[email protected]> *On
> Behalf Of *Ron Baiman
> *Sent:* Wednesday, 1 March 2023 3:59 AM
> *To:* Ye Tao <[email protected]>
> *Cc:* Tom Goreau <[email protected]>; Robert Chris <
> [email protected]>; Douglas Grandt <[email protected]>; peter
> jenkins <[email protected]>; 'Eelco Rohling' via NOAC Meetings <
> [email protected]>; Healthy Climate Alliance <
> [email protected]>; Planetary Restoration <
> [email protected]>; geoengineering <
> [email protected]>; healthy-planet-action-coalition <
> [email protected]>
> *Subject:* Re: [prag] [HCA-list] Make Sunsets stimulates more debate over
> "Geoengineering"- PT Barnum further vindicated!
>
>
>
> BTW, my impetus for launching this thread was to try to avoid making a
> factual error in this Make Sunsets guest blog post (
> https://makesunsets.com/blogs/news/pricing-cooling-credits ) and this
> discussion did indeed (I hope!) lead me to correct the sentence and avoid
> egg on face!
>
>
>
> This is the (edited) sentence in question:
>
>
>
> "And even more alarmingly, a recent draft paper by James Hansen (the
> climate scientist who warned the US Senate
> <https://www.nytimes.com/1988/06/24/us/global-warming-has-begun-expert-tells-senate.html>
> in 1988 that climate change was happening) and coauthors suggests that 7-10
> degrees C may already be in the pipeline
> <https://arxiv.org/ftp/arxiv/papers/2212/2212.04474.pdf> even if we were
> to achieve net-zero today."
>
>
>
> Best,
>
> Ron
>
>
>
> On Tue, Feb 28, 2023 at 10:43 AM Ron Baiman <[email protected]> wrote:
>
> Thank you all!  This has been a good discussion. A copy of Tom's paper is
> attached below.
>
> Best,
>
> Ron
>
>
>
> On Tue, Feb 28, 2023 at 5:50 AM Ye Tao <[email protected]> wrote:
>
> That is way real scientists need to be in the field, at least one day per
> week;)
>
> Cheers,
>
> Ye
>
> On 2/28/2023 6:17 AM, Tom Goreau wrote:
>
> That paper, based on empirical climate data was ignored  by model-oriented
> physicists because it showed their models did not describe the real world
> changes.
>
>
>
> IPCC attacked it because it disagreed with their low consensus values
> based on models that missed most of the feedbacks that we know must operate
> in the Earth climate system from the paleo-climate data.
>
>
>
> Eelco Rohling’s later independent analysis had much more data, and the
> conclusions were very robust.
>
>
>
> In the 33 years since then the models have gotten much better, especially
> Hansen’s, but they still can’t incorporate biological feedbacks that
> physicists don’t understand well enough to model.
>
>
>
>
> *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]* <[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: *Ye Tao <[email protected]> <[email protected]>
> *Date: *Tuesday, February 28, 2023 at 7:34 AM
> *To: *Tom Goreau <[email protected]> <[email protected]>,
> Robert Chris <[email protected]> <[email protected]>, Douglas
> Grandt <[email protected]> <[email protected]>, Ron Baiman
> <[email protected]> <[email protected]>
> *Cc: *peter jenkins <[email protected]>
> <[email protected]>, 'Eelco Rohling' via NOAC Meetings
> <[email protected]> <[email protected]>,
> Healthy Climate Alliance <[email protected]>
> <[email protected]>, Planetary Restoration
> <[email protected]>
> <[email protected]>, geoengineering
> <[email protected]> <[email protected]>,
> healthy-planet-action-coalition
> <[email protected]>
> <[email protected]>
> *Subject: *Re: [prag] [HCA-list] Make Sunsets stimulates more debate over
> "Geoengineering"- PT Barnum further vindicated!
>
>
>
> Dear Tom,
>
> Thank you for sharing your 1990 paper
> <https://www.jstor.org/stable/4313702>.  It is inspiring to see how
> relevant its contents remain 32 years later.
>
> In the paper, you highlight a fitted slope of 0.094C per ppm CO2
> (200-280ppm data range).  Linear extrapolation leads to 26C per doubling of
> CO2.   You correctly pointed out that the extrapolation is not linear, but
> concave down, as shown also in this more recent piece.
> <https://www.nature.com/articles/ngeo3036#:~:text=A%20doubling%20of%20CO2%20is%20estimated%20by%20the%20IPCC,of%203.7%20W%20m%E2%88%922.>
> Visual inspection suggests roughly a difference in slow of X2.   So your
> results are consistent with a ESS, from 280-560 ppm eCO2, of ~10C per
> doubling.
>
> Your analyses thus appear consistent with those of Hansen et al.   And
> Hansen's results are not only for short or intermediate timescales.  The
> 10C per doubling for ESS they advance is for multi-millennia time scales as
> well.
>
> From human and engineering intervention perspectives, the long-term ESS
> stops being relevant beyond ESS>8C per doubling, this is because there is
> no way for civilization to survive past 3-4C.  What is needed is to achieve
> the capacity to bring EEI<0 within a time frame of years to decades, well
> before 2.5C is reached.  Within this period, ECS remains relevant for
> describing reality.
>
> Best,
>
> Ye
>
> On 2/27/2023 1:42 PM, Tom Goreau wrote:
>
> No confusion Ye, the climate record that Eelco and I analyzed reflects the
> LONG-TERM response, not the short one or intermediate ones which Hansen and
> IPCC do, as it integrates over the 1.5 thousand year time lag intrinsically
> caused by ocean mixing.
>
>
>
> The long term prospect is more frightening, and should not be discounted
> away by short sighted analyses.
>
>
>
>
> *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]* <[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: *Ye Tao <[email protected]> <[email protected]>
> *Date: *Monday, February 27, 2023 at 3:36 PM
> *To: *Robert Chris <[email protected]> <[email protected]>,
> Douglas Grandt <[email protected]> <[email protected]>, Ron
> Baiman <[email protected]> <[email protected]>, Tom Goreau
> <[email protected]> <[email protected]>
> *Cc: *peter jenkins <[email protected]>
> <[email protected]>, 'Eelco Rohling' via NOAC Meetings
> <[email protected]> <[email protected]>,
> Healthy Climate Alliance <[email protected]>
> <[email protected]>, Planetary Restoration
> <[email protected]>
> <[email protected]>, geoengineering
> <[email protected]> <[email protected]>,
> healthy-planet-action-coalition
> <[email protected]>
> <[email protected]>
> *Subject: *Re: [prag] [HCA-list] Make Sunsets stimulates more debate over
> "Geoengineering"- PT Barnum further vindicated!
>
>
>
> Dear Ron and Tom,
>
> I think you have misunderstood my comments; they are entirely consistent
> with Hansen's results.  I simply added some details that Hansen probably
> did not realize could help avoid confusing people outside of the simulation
> field.  I suspect some of you were in shock because of the number 10C for
> ESS in the abstract.  But this doesn't mean heating of 10C anytime soon.
> The critical element is time.  ESS applies for thousands of years later.
> What this group had been discussing before I chipped in was about what
> happens by 2100.
>
> By the way, results in Hansen's paper are nothing new, save minor tweaks
> to numbers. It is simply the first time that the author group has collected
> key pieces of the climate puzzle in a comprehensive and cogent fashion.
> The fact that ECS could be up to 5C per W/m2 was known, for example, based
> on results reviewed by Sherwood et al 2020 (ref 28).   I myself, through
> plotting historical data, was able to reproduce, back in 2019, the result
> of ESS ~ 7.5C (assuming aerosol was held constant at some average,
> ill-defined value during 2000-2019).  Compare the following graph I made to
> Hansen's recent writing: "Today’s level of particulate air pollution
> reduces equilibrium warming to about 7°C"
>
> <image001.png>
>
> <image002.png>
>
> @Robert C., please feel free to forward any of my comments to Hansen,
> though they are basically rephrasing results in his paper.  Perhaps the
> above figure could help them making the message clearer, that ESS=10C per
> W/m2 does not imply order 10C warming in our or our children's lifetimes.
> It is also worthwhile citing Snyder's work that I included in my previous
> comments.
>
> Best,
>
> Ye
>
> On 2/27/2023 11:36 AM, Ron Baiman wrote:
>
> Thank you Ye!  I’m going to have to go over this in more detail and try to 
> understand it but for now I think I’m going to stick with the direct quote 
> from Hansen on p. 31 that I referenced and avoid prognosticating on timing 
> until (or if and when) it appears that you and other experts in the field 
> whom I respect have sorted this out more.
>
>
>
> For policy purposes it’s enough to point out that we’re very likely going to 
> be in deep s**t  even if get to net-zero GHG (natural and human) very quickly 
> (which appears highly unlikely at this point) so that direct climate cooling 
> is urgent now as Hansen el al.  point out on p. 37 of the paper!
>
>
>
> Best,
>
> Ron
>
>
>
> Sent from my iPhone
>
>
>
> On Feb 27, 2023, at 8:17 AM, Ye Tao <[email protected]> 
> <[email protected]> wrote:
>
> On 2/27/2023 10:22 AM, Robert Chris wrote:
>
> Hi Ye
>
> Thanks for these comments.  The Hansen et al paper is a prepublication
> draft and I know he is reworking it for final publication.  Would you mind
> if I shared some of your comments with him as it would be hugely valuable
> to have him address some of the points you raise, if he is minded to do
> that.
>
> One of my problems with this paper is my lack of formation in the
> underlying climate science and modelling to be able to undertake a proper
> critical analysis.  Like most others, I am obliged to assume that if Hansen
> is saying it, it must be true.  But I'm sure that even Hansen would
> recognise that that's not necessarily a wise move!
>
> Regards
>
> Robert
>
>
>
> On 27/02/2023 14:17, Ye Tao wrote:
>
> Dear all,
>
> Thank you for a fascinating discussion.  I believe there is a bit of
> confusion, which arises from the differing definitions for ECS (Equilibrium
> Climate Sensitivity, see p4 of article) vs ESS (Earth System Sensitivity,
> also p4).   Bottom line: we will most likely NOT have a 6C increase in
> global average temperature by the end of the century by *holding constant
> the current level of GHG*.  A highly probable range is 2.3C-4C.  This is
> explained below.
>
> ECS is an artificial concept defined to enable computer model development
> and computational thought experiments.  Its assessment requires holding
> constant slow-response components (forests and ice cover).   These
> artificial constraints, which greatly simplify code and speed up
> calculations, cannot be strictly true in nature; we have seen forests
> burning up (cut down increasing quickly due to feedbacks in the human
> system) and we have witness dramatic arctic melting, all within decadal
> time scales.  Therefore, ECS cannot be used directly to predict reality on
> and beyond the time scale on which these processes occur.  Hence, Fig. 4 is
> not a surrogate for reality.
>
> In spite of its artificialness, projections based on a chosen ECS value is
> useful for describing a range of times (year to a few decades) when the
> simplifying assumptions of unchanging land surface types can be taken as
> approximately acceptable.   This is also because some of these changes,
> when they do happen, can have mutually cancelling effects at the level of
> radiative forcing.  For example, darkening arctic oceans could be partially
> compensated for by brighter barren landscape emerging out of clear-cut
> forests and burnt boreal forests.   Within this short time scale, we can
> use ECS and the temperature response function of your (favorite) model to
> semi-quantitatively project future temperature trends.  See Fig. 4 of paper
> for examples based on the GISS models.    For all intents and purposes, you
> can trust Fig. 4, *at the very most*, to Year = 100 on the X axis.
>
> Beyond Year = 100, Fig. 4 is no longer useful for future projections.  All
> we can say is that paleoclimate data *potentially* provides a constraint
> on how bad things could get thereafter.  This is done by Hansen et al in
> Figure 7.   Reality is most likely between Figures 4 and a scaled version
> (ESS/ECS).
>
> Regarding ESS, there is one caveat to keep in mind.  The caveat is that*
> the ESS value provided in the paper (10C per doubling of eCO2) is based on
> historical data at temperature ranges cooler than that of the present and
> near-future*.  And we are obviously heading to hotter, unprecedentedly
> warm territories for which paleoclimate data do not exist.  In other words,
> ESS is itself a function of the temperature at which it is evaluated
> (taking the slope of the tangent point along the temperature axis,
> theoretically speaking.  Linear fitting to a range of temperature data in
> practice.).
>
> There is evidence that ESS is a positive function of temperature: SNYDER,
> C. W. Revised estimates of paleoclimate sensitivity over the past 800,000
> years. 2019. *Climatic Change*
> <https://link.springer.com/article/10.1007/s10584-019-02536-0>. 156.
> 121–138 <https://link.springer.com/article/10.1007/s10584-019-02536-0>.
> The implication would be that going forward, ESS could well be larger than
> the 10C per doubling of eCO2 Hansen suggests.  Oops! Luckily for us
> mortals, or unluckily since you are a curious person, no one on this list
> would live long enough, which requires waiting several thousand years, to
> see experimental verification of the actual value of ESS valid for the
> hotter end of the temperature range.
>
> Practically, in thinking about a real-world trajectory, one can consider
> the effective, realized climate sensitivity to morph towards larger values
> as time passes, from the small Transient climate response (TCR = 2C per
> doubling), to ECS (4C per doubling), and then to ESS (>10C per doubling).
> Discussions about what happens by the end of the century therefore could
> use values intermediate between ECS and ESS, i.e. somewhere between 4C per
> doubling of CO2 and somewhat larger than 10C per doubling of CO2.
>
>
> The implication of the discussion above is that your previous
> understanding of global warming by the end of the century is still valid.
> At the current level of GHG, with a rapidly successful decarbonization
> program that eliminated fossil fuel aerosols, we will likely see warming
> somewhere between 2.3C (as indicated by Figure 4, and the fact that a ECS
> of 3.5 was used in its making, in stead of a more likely 4) and 6C (scaled
> by the ESS/ECS=3 ratio).  The actual value is more likely to be on the
> lower end of this range, i.e. between 2.3C and 4C.
>
>
> Note, importantly, that assumptions also include immediate carbon
> neutrality and holding constant current GHG levels, which for those of us
> who really thought deeply and understood the impossibility of meaningful
> CO2 capture, can readily accept as being compatible with a voluntary or
> involuntary contraction of the human enterprise, constrained by primary
> productivity projections and the inevitably increasing cost of energy
> production (declining EROI) going forward.
>
>
> Cheers,
>
> Ye
>
>
>
>
> On 2/27/2023 8:22 AM, Robert Chris wrote:
>
> Doug and Ron
>
> Here's how I arrived at my conclusions.
>
> From the extracts below, I conclude, given that by 2020 (or thereabouts)
> we had already doubled atmospheric GHGs from pre-industrial including non-CO
> 2 GHGs, that we will eventually warm the surface by 10oC with a climate
> response e-folding time of ~100 years provided the offsetting cooling from
> anthropogenic aerosols continues to decline and is eventually largely
> eliminated.  That means that by 2050 the warming would be ~2.4oC less the
> residual aerosol cooling of, say 0.4oC, giving their estimate of 2oC.
>
> ·        When all feedbacks, including ice sheets, are allowed to respond
> to the climate forcing, the equilibrium response is approximately doubled,
> i.e., ESS is ~ 10°C.
>
> ·        Yet the time required for the [improved] model to achieve 63% of
> its equilibrium response remains about 100 years.  (See Fig 4b – note log
> x-axis.)
>
> ·        With all trace gases included, the increase of GHG effective
> forcing between 1750 and 2021 is 4.09W/m2, which is equivalent to
> increasing the 1750 CO2 amount (278 ppm) to 561 ppm (formulae in
> Supporting Material).  We have already reached the GHG climate forcing
> level of doubled CO2.  [Note that they develop a scaling factor of 2.4oC
> per W/m2 which corresponds to 10oC for the 4W/m2 of current GHG forcing.]
>
> ·        Declining aerosol amount implies acceleration of global warming
> above the 1970-2010 rate.
>
> ·        Global temperature responds reliably to climate forcing on
> decadal time scales, with about 50% of the response in the first decade,
> with about 15% more in the next 100 years
>
> ·        we expect some [aerosol] reduction and a forcing increase of at
> least +0.1 W/m2 per decade [between 2010 and 2050].
>
> ·        we estimate that the global warming rate in 2010-2040 will be at
> least 50% greater than in 1970-2010, i.e., at least 0.27°C per decade.
>
> ·        The poster child for warming in the pipeline is Fig. 7, showing
> that equilibrium warming for today’s GHG level, including slow feedbacks,
> is about 10°C.  Today’s level of particulate air pollution reduces
> equilibrium warming to about 7°C.
>
> ·       The 7-10°C global warming is the eventual response *if today’s
> level of GHGs is fixed and the aerosol amount is somewhere between its year
> 2000 amount and preindustrial amount*. (emphasis added) [Note that the
> assumptions here are that ‘today’s level of GHGs is fixed’, which I take to
> mean that future emissions are ignored, and aerosols are currently lower
> than they were in 2000.]
>
> Here's a simple graph showing the realisation of 10oC of warming with an
> e-folding time of 100 years.  Assume it starts in 2020 or thereabouts (when
> atmospheric CO2e reached 556ppmv.).
>
> <image003.png>
>
> Regards
>
> Robert
>
>
>
> On 27/02/2023 03:50, Douglas Grandt wrote:
>
> Ron and Robert,
>
>
>
> Visually, the shape of the curve is something like this … more or less …
> as best I can fathom.
>
>
>
> This is my interpretation of Hansen's assumptions and conclusions, but I
> very well could be wrong …
>
>
>
> Perhaps somebody has chart generating software that would be more precise
> than my eyeball.
>
>
>
> Doug
>
>
>
>
>
>
>
>
>
> On Feb 26, 2023, at 8:58 PM, Ron Baiman <[email protected]> wrote:
>
>
>
> *6.3 C (63% of 10) by 2020*
>
>
>
> On Sun, Feb 26, 2023 at 7:56 PM Ron Baiman <[email protected]> wrote:
>
> Robert,
>
>
>
> Do you have a page number or an explanation of how you arrived at your
> figures?   In the paper(https://arxiv.org/abs/2212.04474) on p. 31 I'm
> finding: "The 7-10 C global warming is the eventual response if today's
> level of GHGs is fixed and the aerosol amount is somewhere between its year
> 2000 amount and preindustrial amount."  but the key temp Figure 7 on p. 18
> doesn't extend beyond 2025.  In the section on Climate response times (p.
> 32) the paper states that the in 2020 GISS GCM: "...the time required for
> the model to achieve 63% of its equilibrium response remains about 100
> years" which would put the expected temp based on forcing estimated in the
> paper at 6.3 C (63% or 10) by 2023.  Is this where you're getting your 6.3
> C by 2120 from?  Unfortunately, I have not had the time (and probably not
> the background) to go through the entire paper and understand it well!
>
>
>
> Best,
>
> Ron
>
>
>
>
>
> On Sun, Feb 26, 2023 at 7:09 PM Ron Baiman <[email protected]> wrote:
>
> Thanks for the correction Robert!
>
> Sent from my iPhone
>
>
>
>
> On Feb 26, 2023, at 6:41 PM, Robert Chris <[email protected]> wrote:
>
> Ron
>
> Hansen et al say that the 10degC is based on 'today's GHG level' and that
> it has an e-folding time of 100 years.  That implies 6.3degC by 2120 and a
> bit less by 2100.
>
> Regards
>
> Robert
>
>
>
>
>
> On 26/02/2023 23:43, Ron Baiman wrote:
>
> Jim Hansen et al (https://arxiv.org/abs/2212.04474 ) believe that
> existing legacy GHG's  have put us in "in the pipeline" for 10 degrees C
> warming by 2100!
>
>
>
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