Thanks, Dan. It's a similar story with ECS implied by comparison of glacial and interglacial states.
The forcings that maintain the glacial-interglacial temperature change are almost entirely: (1) Atmosphere: GHG change, (2) Surface: change of ice sheet size Vegetation change also affects surface albedo, but it's a small effect and an estimate for it is included, even in our 1984 paper. Biology affects aerosols, but glacial-interglacial aerosol change is a climate feedback, part of the cloud-aerosol feedback (not a forcing); the biology effect is included in the empirical global temperature change. [Why is the biology effect (change of surface albedo due to change of vegetation distribution) included as a forcing, while the biology effect on aerosols is bookkept as a feedback? Because we have knowledge of the change of surface vegetation distribution, while the N aerosol types are unknown, especially their main effect, which would be via impact on clouds. So, the only choice is to leave it in the feedback category. These arbitrary forcing/feedback designations for vegetation and aerosols are small potatoes compared with GHG and ice sheet albedo changes.] Biology was sure a BFD in maintaining the fiction of 3C sensitivity for several decades. CLIMAP and MARGO estimated that LGM cooling was only about 3.6C based on their assumption that the microscopic marine biology would migrate to stay in the same temperature range where they exist today. Actual LGM cooling was almost a factor of two larger. Jim On Tue, May 20, 2025 at 12:52 PM Dan Miller <[email protected]> wrote: > Hi Herb: > > I read Dr. Mararieva’s comments and I don’t believe she understood Jim’s > recent communication fully. I explain Jim’s latest communication it in my > recent Climate Chat program <https://youtube.com/live/NxV1IbHt7fU>. In a > nutshell, the Earth dimmed by 0.5% in the past 25 years. There are 3 main > causes: 1) Less sea ice, 2) changes to aerosols, and 3) could feedbacks. > We know (1) well from direct observation. The IPCC thinks (2) is less than > Jim does, but if that it true then (3) is even bigger than Jim says. The > bottom line is that there are large cloud feedbacks (less clouds as the > planet warms) which implies a large ECS (4.5ºC). See my interview > with George Tselioudis for more on cloud feedback: > > Global Warming➔Fewer Clouds➔More Warming! with *George Tselioudis* > > https://youtube.com/live/suFZb2ViHoA > > While biological processes of course play a role in climate change, it’s > hard to see how a biological process played a role in changing the Earth’s > albedo by 0.5% in the past 25 years, unless such process plays a major role > in short-term cloud cover. Even if it did, it does not change Jim’s > conclusions since he doesn’t say why the cloud feedback is so large, just > that it is. > > Dan > > > On May 19, 2025, at 6:09 PM, H simmens <[email protected]> wrote: > > Jim, > > I know that your time is short but if you have a few moments I’d love to > get your response to Dr Anastassia Mararieva’s (who has a PhD in > atmospheric physics and formulated the concept of the biotic pump ) article > on Substack published today. > > She argues that the biosphere is neglected in both your work and the work > of most mainstream climate modelers and scientists (I’m oversimplifying her > argument of course but it touches on ECS, aerosols, clouds and much more.) > > Thanks, > > Herb > > > <824ddf00-4ae0-486f-8adc-ed98368ab92b_610x728.png> > > On the scientific essence of Dr. James Hansen's recent appeal > <https://open.substack.com/pub/bioticregulation/p/on-the-scientific-essense-of-dr-james?r=1o7sd&utm_medium=ios> > open.substack.com > <https://open.substack.com/pub/bioticregulation/p/on-the-scientific-essense-of-dr-james?r=1o7sd&utm_medium=ios> > > <https://open.substack.com/pub/bioticregulation/p/on-the-scientific-essense-of-dr-james?r=1o7sd&utm_medium=ios> > > > Thanks, > > Herb > > > Herb Simmens > Author of *A Climate Vocabulary of the Future* > “A SciencePoem and an Inspiration.” Kim Stanley Robinson > @herbsimmens > HerbSimmens.com > > > On May 19, 2025, at 8:39 PM, James Hansen <[email protected]> wrote: > > > o.k., well-taken -- I just wanted to make the point that, if you start out > accepting IPCC's best estimate for aerosol forcing, there is a human > tendency, given the choice of many models/parameters, to choose the > model/parameters that yield realistic global warming -- and this is a way > to "bake in" the ECS (3C for doubled CO2) that agrees with the assumed > (IPCC) aerosol forcing. > Jim > > On Mon, May 19, 2025 at 8:20 PM Michael MacCracken <[email protected]> > wrote: > >> Hi Jim--No need for a back and forth. I did not mean to dismiss your >> calculation of sensitivity possibly being 4.5 C and don't disagree that the >> set of parameters used in models now do tend toward yielding a 3 C >> sensitivity. Indeed, I found your latest results very interesting, high as >> the sensitivity seems if one goes back to when the CO2 concentration is >> thought to be 4 or more times preindustrial. >> >> In my interactions with Ron and others, I was interpreting their remarks >> to be saying that the climate sensitivity was directly specified as 3 C in >> the models independent of how the processes work and come together, and I >> wanted to say that that is not the case. At least that was what I was >> intending to say. I should perhaps have made more clear your point that >> some of the parameters in the existing model should, based on the time >> history of observations and seeking to match the model results to them >> could well be indicating that different parameters regarding cloud feedback >> are likely the case and this could lead to the higher sensitivity and >> improved the match to the multiple types of observations that you consider. >> >> Good luck for your move back to New York City. >> >> Best, Mike >> On 5/19/25 8:00 PM, James Hansen wrote: >> >> Hi Mike et al., >> >> I can't get involved in a back-and-forth -- we are in the process of >> moving back to NYC, to live in a Columbia apartment to avoid time wasted in >> commuting and taking care of a house/property. However, I'm surprised by >> your comment, Mike. Most GCM groups make hundreds, if not more, GCM runs >> between one IPCC report and the next, and there are hundreds, if not more, >> model parameters. There is a widespread, if not universal, tendency to >> prefer those model configurations that yield a magnitude of warming in the >> past 200 years that is consistent with observations. In this way, wittingly >> or not, the 3C sensitivity is "baked into" the models -- because, as we >> showed in our "Acceleration" the usual aerosol forcing employed is close to >> the IPCC best estimate for aerosol forcing. As shown by a graph in the >> Supplementary Information of our paper, the change of the IPCC aerosol >> forcing during the period of rapid warming is negligible. In such case, the >> climate sensitivity required to match the observed warming rate is ~3C for >> 2xCO2. However, if the aerosol forcing increased by ~0.5 W/m2 (became more >> negative) during 1970-2005, as simulated by Bauer et al. and as >> independently inferred in our paper, then a climate sensitivity of ~4.5C is >> required to match the observed warming. >> >> However, the temperature change in the last 200 years is only one of the >> three independent ways that we obtain the 4.5C sensitivity, and the other >> two are much cleaner, independent of the GCM issues. >> >> High climate sensitivity demanded by large cloud feedback, clearly shown >> by Earth's darkening in the past 25 years, is summarized in the recent >> communication to my email list. >> >> The third method is described in our "Global warming in the pipeline" >> paper: comparison of equilibrium glacial and interglacial climates. For >> several decades, based largely on CLIMAP and "confirmed" by MARGO, it was >> believed that the LGM was only 3-4C colder than the Holocene. Thanks >> especially to Alan Seltzer, we now know that the LGM was 6-7C colder, which >> demands the higher ECS -- several new paleo studies confirm the high ECS. >> >> Best, Jim >> >> On Mon, May 19, 2025 at 3:39 PM 'Michael MacCracken' via geoengineering < >> [email protected]> wrote: >> >>> Ron et al.--Just a note that the 3 C sensitivity is not "embedded" in >>> the climate models. That is the value that emerges from the representations >>> of the various physical processes that play out against each other. So, >>> assuming the observations and resulting analyses are accurate, for there to >>> be a higher sensitivity, it might be that some of the processes are not >>> parameterized in a way that fully represents possibilities and realities >>> (observations to calibrate parameterizations can be drawn from only the >>> conditions we are experiencing), some processes are not represented at >>> all (viewed as long-term such as isostatic rebound, etc.), the resolution >>> of the models is not fine enough to treat aspects of the processes, etc. In >>> any case, however, the 3 C sensitivity is not built into the models. >>> >>> Mike >>> On 5/19/25 1:49 PM, Ron Baiman wrote: >>> >>> Thank you LDM and Dan, >>> >>> @LDM: >>> >>> (IMO) Thanks for sharing! IMO this recent Hansen and Kharecha >>> Newsletter with further evidence supporting a climate sensitivity of 4.5 >>> rather than the established IPCC value of 3.0 that is (as I understand it) >>> embedded in most current climate models, is excellent and should be widely >>> distributed, per these last two paragraphs: >>> >>> "Criticisms of the Acceleration paper in the media did not address the >>> physics in our three assessments of >>> climate sensitivity. Instead, criticisms were largely ad hoc opinions, >>> even ad hominem attacks. How can >>> science reporting have descended to this level? Climate science is now >>> so complex, with many sub- >>> disciplines, that the media must rely on opinions of climate experts. >>> Although there are thousands of >>> capable scientists in these disciplines, the media have come to depend >>> on a handful of scientists, a clique >>> of climate scientists who are willing, or even eager, to be the voice of >>> the climate science community. >>> But are they representative of the total community, of capable >>> scientists who focus on climate science? >>> We have lamented9 the absence of scientists with the breadth of >>> understanding of say Jule Charney or >>> Francis Bretherton,10 or our beloved, sometimes crotchety, former >>> colleague, Wally Broecker. However, >>> the truth is that there are many scientists out there with a depth of >>> understanding at least as great as the >>> clique of scientists that the media rely on. Given the success of this >>> clique in painting us as outliers, we >>> are dependent on the larger community being willing to help educate the >>> media about the current climate >>> situation. For that purpose, we will discuss – one-by-one in upcoming >>> communications – several of the >>> matters that are raised in our papers. Thanks for your attention." >>> >>> @Dan: Thanks for sharing! I will definitely give this a listen! >>> >>> Best, >>> Ron >>> >>> >>> On Sun, May 18, 2025 at 4:04 PM LDM <[email protected]> wrote: >>> >>>> >>>> https://www.columbia.edu/~jeh1/mailings/2025/CloudFeedback.13May2025.pdf >>>> >>>> Large Cloud Feedback Confirms High Climate Sensitivity >>>> James Hansen and Pushker Kharecha >>>> 13 May 2025 >>>> >>>> Abstract. >>>> >>>> Earth’s albedo (reflectivity) declined over the 25 years of precise >>>> satellite data, with the decline so large that this change must be mainly >>>> reduced reflection of sunlight by clouds. Part of the cloud change is >>>> caused by reduction of human-made atmospheric aerosols, which act as >>>> condensation nuclei for cloud formation, but most of the cloud change is >>>> cloud feedback that occurs with global warming. The observed albedo change >>>> proves that clouds provide a large, amplifying, climate feedback. This >>>> large cloud feedback confirms high climate sensitivity, consistent with >>>> paleoclimate data and with the rate of global warming in the past century. >>>> >>>> >>>> https://youtu.be/NxV1IbHt7fU >>>> >>>> When Will We Go Over 2ºC? & Hansen's Cloud Update >>>> <https://www.youtube.com/@climatechat> >>>> >>>> >>>> On Sun, May 18, 2025 at 9:09 PM Ron Baiman <[email protected]> wrote: >>>> >>>>> Wow! Thanks for sharing Renaud. I haven't read it but from the >>>>> abstract it (very unfortunate for all of us humans and most other >>>>> species, >>>>> but not really surprising for many of us humans) looks like forecasts of >>>>> Hansen et al. 2024 are being vindicated! >>>>> Best, >>>>> Ron >>>>> >>>>> >>>>> On Wed, May 14, 2025 at 9:51 AM Renaud de RICHTER < >>>>> [email protected]> wrote: >>>>> >>>>>> Earth's Energy Imbalance More Than Doubled in Recent Decades >>>>>> https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024AV001636 >>>>>> Abstract >>>>>> >>>>>> Global warming results from anthropogenic greenhouse gas emissions >>>>>> which upset the delicate balance between the incoming sunlight, and the >>>>>> reflected and emitted radiation from Earth. The imbalance leads to energy >>>>>> accumulation in the atmosphere, oceans and land, and melting of the >>>>>> cryosphere, resulting in increasing temperatures, rising sea levels, and >>>>>> more extreme weather around the globe. Despite the fundamental role of >>>>>> the >>>>>> energy imbalance in regulating the climate system, as known to humanity >>>>>> for >>>>>> more than two centuries, our capacity to observe it is rapidly >>>>>> deteriorating as satellites are being decommissioned. >>>>>> Key Points >>>>>> >>>>>> >>>>>> - >>>>>> >>>>>> Earth's energy imbalance more than doubled in recent decades >>>>>> - >>>>>> >>>>>> The large trend has taken us by surprise, and as a community we >>>>>> should strive to understand the underlying causes >>>>>> - >>>>>> >>>>>> Our capability to observe the Earth's energy imbalance and budget >>>>>> terms is threatened as satellites are decommissioned >>>>>> >>>>>> Plain Language Summary >>>>>> >>>>>> Global warming is caused by the imbalance between the incoming >>>>>> radiation from the Sun and the reflected and outgoing infrared radiation >>>>>> from the Earth. The imbalance leads to energy accumulation in the >>>>>> atmosphere, oceans and land, and melting of the cryosphere, resulting in >>>>>> increasing temperatures, rising sea levels, and more extreme weather >>>>>> around >>>>>> the globe according the the United Nations Intergovernmental Panel on >>>>>> Climate Change (IPCC). Observations from space of the energy imbalance >>>>>> shows that it is rising much faster than expected, and in 2023 it reached >>>>>> values two times higher than the best estimate from IPCC. We argue that >>>>>> we >>>>>> must strive to better understand this fundamental change in Earth's >>>>>> climate >>>>>> state, and ensure our capacity to monitor it in the future. >>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "Healthy Planet Action Coalition (HPAC)" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to >>>>>> [email protected]. >>>>>> To view this discussion visit >>>>>> https://groups.google.com/d/msgid/healthy-planet-action-coalition/CAHodn9-e2iCfiPJYDRnv2TTcjgCueetUw9Fs83Tp48B2gA0jJA%40mail.gmail.com >>>>>> <https://groups.google.com/d/msgid/healthy-planet-action-coalition/CAHodn9-e2iCfiPJYDRnv2TTcjgCueetUw9Fs83Tp48B2gA0jJA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> >>>>> >>>>> >>>>> -- >>>>> Healthy Planet Action Coalition <http://www.healthyplanetaction.org/> >>>>> YouTube Channel >>>>> <https://www.youtube.com/channel/UCdt5vatByfyg-Pm9Vu6ahZg> >>>>> @HPACoalition (Bluesky and Twitter/X) >>>>> Addressing the Urgent Need for Direct Climate Cooling: Rationale and >>>>> Options <https://academic.oup.com/oocc/article/4/1/kgae014/7731760> >>>>> Baiman et al. 2024. *Oxford Open Climate Change* >>>>> An Open Letter to the IMO Supporting Maritime Transport that Cools the >>>>> Atmosphere While Preserving Air Quality Benefits >>>>> <https://academic.oup.com/oocc/article/4/1/kgae008/7706251>. Baiman >>>>> et al. 2024. *Oxford Open Climate Change* >>>>> >>>> >>> >>> -- >>> Healthy Planet Action Coalition <http://www.healthyplanetaction.org/> >>> YouTube Channel >>> <https://www.youtube.com/channel/UCdt5vatByfyg-Pm9Vu6ahZg> >>> @HPACoalition (Bluesky and Twitter/X) >>> Addressing the Urgent Need for Direct Climate Cooling: Rationale and >>> Options <https://academic.oup.com/oocc/article/4/1/kgae014/7731760> >>> Baiman et al. 2024. *Oxford Open Climate Change* >>> An Open Letter to the IMO Supporting Maritime Transport that Cools the >>> Atmosphere While Preserving Air Quality Benefits >>> <https://academic.oup.com/oocc/article/4/1/kgae008/7706251>. Baiman et >>> al. 2024. *Oxford Open Climate Change* >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "geoengineering" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/geoengineering/CAPhUB9CnQHnNxxw0m238XK9mxSatsHedxndUf7vO0KoQkVeiXQ%40mail.gmail.com >>> <https://groups.google.com/d/msgid/geoengineering/CAPhUB9CnQHnNxxw0m238XK9mxSatsHedxndUf7vO0KoQkVeiXQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "geoengineering" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/geoengineering/4e23a031-1d90-429f-b962-a428e82fc7ac%40comcast.net >>> <https://groups.google.com/d/msgid/geoengineering/4e23a031-1d90-429f-b962-a428e82fc7ac%40comcast.net?utm_medium=email&utm_source=footer> >>> . >>> >> >> >> -- >> Jim Hansen, Director >> Climate Science, Awareness and Solutions Program >> Columbia University Earth Institute >> >> -- >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion visit >> https://groups.google.com/d/msgid/geoengineering/CAEL%2B3vM1eBgxrNdGNjtUOKv75kMx43UgfVnEu-T06SL7wOhYDQ%40mail.gmail.com >> <https://groups.google.com/d/msgid/geoengineering/CAEL%2B3vM1eBgxrNdGNjtUOKv75kMx43UgfVnEu-T06SL7wOhYDQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> > > -- > Jim Hansen, Director > Climate Science, Awareness and Solutions Program > Columbia University Earth Institute > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/geoengineering/CAEL%2B3vO5E93xpZ7AMjTnj2ZAW-eatojgqdgaHCe0MNaVqG7dOw%40mail.gmail.com > <https://groups.google.com/d/msgid/geoengineering/CAEL%2B3vO5E93xpZ7AMjTnj2ZAW-eatojgqdgaHCe0MNaVqG7dOw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > > -- > You received this message because you are subscribed to the Google Groups > "Carbon Dioxide Removal" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/CarbonDioxideRemoval/CB437C74-6612-4B50-8265-C1AE6E70E98C%40gmail.com > <https://groups.google.com/d/msgid/CarbonDioxideRemoval/CB437C74-6612-4B50-8265-C1AE6E70E98C%40gmail.com?utm_medium=email&utm_source=footer> > . > > -- Jim Hansen, Director Climate Science, Awareness and Solutions Program Columbia University Earth Institute -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/geoengineering/CAEL%2B3vMiZP8F10jcFOhDVnrZH8XOZqp1DKitmpyE%2BYgwsGi8Pw%40mail.gmail.com.
