Jim,I still argue water vapour 51% (62% no clouds ) and 19% ( 25%) contributes to IR warming and co2 increases now no longer dominate the rises. With es(T) at 7% for each degree rise in surface air temperatures, then by 2-3 C rise gives a huge positive feedback , clouds or no clouds. A plot on a Elsaser diagram shows this. The radiative models don’t include it properly. Bignell’s water vapour continuum paper shows it works. Study of the planets mars and venus shows it.
Thus in my opinion ECS is bigger than 5 ( may be 8) C. Look at the steepness of the current temperature curve increase. If ECS was say 4 the hysterisis would start to flatten off and it’s not.
Thus I do think lovelock ( re verge of gaia, 2009) is correct , catastrophic weather events start by 2035 and martyn rees ( astronomer royal’s ) prediction for the end of the century are in the right ball park. Best wishes Alan
T --- Alan Gadian, UK. Tel: +44 / 0 775 451 9009 T --- 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 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. 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
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
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Thanks,
Herb
Herb Simmens
Author of A Climate Vocabulary of the Future “A SciencePoem and an Inspiration.” Kim Stanley Robinson
@herbsimmens
HerbSimmens.com
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
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,
(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
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.
When Will We Go Over 2ºC? &
Hansen's Cloud Update
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
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.
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