Dear Colleagues, Again, I'm forwarding my post to the broader community. There are many more posts on this topic in the NOAC thread.
Best, Ron ---------- Forwarded message --------- From: Ron Baiman <[email protected]> Date: Fri, May 26, 2023 at 1:33 PM Subject: Re: FW: Equilibrium Warming = Committed Warming? To: Clive Elsworth <[email protected]> Cc: James Hansen <[email protected]>, <[email protected]> Thank you Jim (and Clive, et al.), I think this is confusing to non-climate scientists (like myself) because: a) "Long-term equilibrium" in this case is a hypothetical (per your post: " the present atmospheric composition, assuming that the composition will stay as it is today") that is misinterpreted as a "net zero today" condition (I initially misinterpreted this way). The problem is that the broad public does not realize that maintaining such a condition would require continued emissions of GHG's after (human, human-induced, and natural) "net zero" at a level that would precisely offset "post-net zero" natural GHG fall-out and ocean uptake, to maintain "the present atmospheric condition". b) Which means that this "long-term equilibrium" cannot exist in the real world as GHG atmospheric composition will not stay constant but either: a) *increase* as the forcing and warming tends (in the absence of direct climate cooling) in your figures 28 and 25 suggest, or b) *decrease* if IPPC fantasies of " Projected global warmings continually rachet down as countries agree to more ambitious goals for future emission reductions." In this sense "committed warming" for those who believe that a) is mch more realistic (as you and I think everyone on this list does) would mean that we are now "committed" to "more than" 7-10 C in the long-run if we do not directly cool , and for those who believe (or pretend to) believe b) whatever estimated warming the "committed" targeted GHG emissions reduction and draw down would produce as I think you're saying (see c) below). c) Related to this, another source of pubic confusion is thinking that "net zero" would mean that global warming will either: a) stay *constant* as atmospheric GHG stock will then be constant (as I initially thought), or b) *decline* if global warming is mistakenly viewed as being correlated with GHG emission flow rather than atmospheric GHG stock. Whereas, per Zeke Hausfather's reporting ( https://www.carbonbrief.org/explainer-will-global-warming-stop-as-soon-as-net-zero-emissions-are-reached/ ), current modeling suggests that: c) warming will remain *constant* even though GHG in the atmosphere would *decline* from natural fall out and ocean uptake due to increasing release of accumulated ocean surface heat into the atmosphere. This latter point suggests to me that not only must we urgently *deploy direct climate* cooling to reduce radiative forcing from the sun but also try to cool ocean surface temperatures, as (even it were possible) it would be a mistake to try to use GHG drawdown to offset transient (though for at least 50 years after net-zero as I recall from the modeling) continued warming from ocean surface heat, as there would then be a risk of excessive cooling when ocean-atmosphere temperature equilibrium was reached. This I think is a reason to look at a wide array of potential direct climate cooling techniques including but not exclusively SRM ( https://pdfhost.io/v/pR4xEbZzO_The_Case_for_Urgent_Direct_Climate_Cooling040223 ). Jim et al, your thoughts on any of this would, of course, be greatly appreciated! Best, Ron > > > > > View this email in your browser > <https://mailchi.mp/caa/equilibrium-warming-committed-warming?e=94785a09ba> > > > > A PDF of this Communication is available on my* webpage > <https://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=b267674634&e=94785a09ba>*, > along with prior Communications and other resources. > > > > [image: Image removed by sender. Tweet to your followers] > <https://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=07e86ee145&e=94785a09ba> > > Tweet to your followers > <https://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=4972d0f33e&e=94785a09ba> > > [image: Image removed by sender. Share on your Facebook] > <https://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=0f641bc6d4&e=94785a09ba> > > Share on your Facebook > <https://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=993d5d40a7&e=94785a09ba> > > [image: Image removed by sender. Forward to your friends] > <https://us1.forward-to-friend.com/forward?u=0ebaeb14fdbf5dc65289113c1&id=3cd4f7a4ac&e=94785a09ba> > > Forward to your friends > <https://us1.forward-to-friend.com/forward?u=0ebaeb14fdbf5dc65289113c1&id=3cd4f7a4ac&e=94785a09ba> > > [image: Image removed by sender.] > > > > *Fig. 28. Annual growth of climate forcing by GHGs including the part of > O3 forcing not included in the CH4 forcing. MPTG and OTG are Montreal > Protocol and Other Trace Gases.* > > > > > *Equilibrium Warming = Committed Warming?* > > > 25 May 2023 > James Hansen > > > > Some people on Twitter interpreted the statement: *“Equilibrium global > warming including slow feedbacks for today’s human-made greenhouse gas > (GHG) climate forcing (4.1 W/m2) is 10°C, reduced to 8°C by today’s > aerosols” *in our draft paper “Global Warming in the Pipeline > <https://columbia.us1.list-manage.com/track/click?u=0ebaeb14fdbf5dc65289113c1&id=c5aca25026&e=94785a09ba>” > as indicating that the world is committed to warming of 10°C. The word > “committed” or “commit” does not appear in our paper. If it had, it would > have been in a statement such as “the world needs to commit to global > cooling of about 1°C for the sake of young people and future generations.” > > Equilibrium warming is a useful concept employed for more than a century, > e.g., in the studies by Arrhenius in the 1890s and Charney in the 1970s. > Equilibrium response is the global temperature change after the climate > system restores energy balance following imposition of a climate forcing. > One merit of our analysis of Cenozoic (past 66 million years) climate is > that it reveals that the present human-made GHG (greenhouse gas) forcing is > already greater than the GHG forcing at the transition from a nearly > unglaciated Antarctica to a glaciated continent. Yes, if we leave > atmospheric composition as it is today, sea level will eventually rise > about 60 m (200 feet). Of course, none of us would be there to see it. > However, it’s not the new equilibrium at +200 feet that’s of most concern, > it’s the chaos that ensues once ice sheet collapse begins in earnest. > > That chaos was the topic of our paper[1] “Ice Melt, Sea Level Rise and > Superstorms,” which was blackballed by IPCC (Intergovernmental Panel on > Climate Change). In that paper, we conclude that continuation of GHG > emissions along the path that the world is on will lead to shutdown of the > overturning (North Atlantic and Southern Ocean) circulations this century > and sea level rise of several meters on a time scale of 50-150 years. As > yet, little has changed to get us off that path. You would not know that > from the communications of the United Nations COPs (Conferences of the > Parties) and their scientific advisory body, the IPCC. Projected global > warmings continually rachet down as countries agree to more ambitious goals > for future emission reductions. If you take those plans plus $2.75 you can > get a ride on New York City’s subway (which, BTW, is safe and efficient, > albeit ancient – New York City is again a good place to visit). > > Physics is a description of the real world. So, climate science should be > focused on data. That’s the way science is supposed to work. However, IPCC > is focused on models. Not just global climate models (GCMs), but models > that feed the models, e.g., Integrated Assessment Models (IAMs) that > provide scenarios for future GHG levels. These models are useful and even > necessary for analysis of the complex climate system, but sometimes the > models contain hocus-pocus. As we mention in our current paper, they can > assume, in effect, that “a miracle will occur.” So, the models need to be > continually checked against the real world. > > Our research is focused on real world data and comparison with models, > with the hope of gaining insights about how the climate system works and > where the real world is headed. Fig. 28 (lead figure) shows the annual > increase of GHG climate forcing based on real world data (which, BTW, is > continually updated and made available by Ed Dlugokencky of the NOAA Earth > System Research Laboratory; Ed is an unsung hero in the climate change > story). Specifically, Fig. 28 compares the real-world growth rate of GHG > forcing with the RCP2.6 scenario, which is used in IPCC’s AR5 report as a > scenario that would limit global warming to about 2°C. Figure 28 shows that > an enormous gap has opened between the real world and RCP2.6. The “miracle” > in RCP2.6 is largely an assumption of negative emissions via power plants > that burn biofuels, capturing and sequestering the CO2. Also beware of > nations promising “net zero” emissions without defining what they mean. As > discussed in our paper, the present policy approach is not working and it > is not likely to work. For example, the cost to close the gap in Fig. 28 > via carbon capture and storage is estimated as $3.4-7.0 trillion per year – > that’s the annual, growing cost. That miracle is not likely to happen. > > There’s no time to get involved in Twitter wars. It’s disappointing that > scientists who once contributed to research progress, but now enjoy > twittering, do not correct a nonscientist’s assumption that equilibrium > warming = committed warming but instead allow the misconception to persist > and then use it to insist that we are “wrong” in our assessment. Further, > their claim that current scientific literature points to eventual global > warming being kept “well below 2°C” as being consistent with real world > trends and policies is egregious, an uncritical acceptance of models and > the assumptions that went into them. > > > > [image: Image removed by sender.] > > > > *Fig. 25. Global temperature relative to 1880-1920.* > > > > Let’s end with another figure from our paper, Fig. 25 (above), which > compares the long-term global temperature trend with our prediction of > accelerated warming that accounts for declining atmospheric aerosols and an > uptick in GHG growth rates. As much as possible, the projection is based on > data: measured global energy imbalance and indirect indications of > declining aerosol amount. It has become popular to say that the emerging El > Nino will cause global temperature to soon exceed 1.5°C. We don’t know that > for certain, but we can expect it to reach at least +1.4-1.5°C. An El Nino > spurred global temperature close to +1.5°C will not provide a valid measure > of what the world will be like when the trend-line reaches +1.5°C, but the > El Nino spurred peak temperature will provide a first indication of whether > there is a new, accelerated trend line. 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