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Comments 651 to 700:

  1. Can we still avoid 1.5 degrees C of global warming?

    Bob @ 3 -

    I wondered if kar meant stippled?

  2. Can we still avoid 1.5 degrees C of global warming?

    kar @ 2:

    Your answer to the question about pre-1990 data is not hard to find. The authors of the blog post kindly added a link to the image source in the caption.

    If you follow that link, you can download the report. If you go to the original version of the figure in the report, it says:

    Sources: Upper panel: Historical data from the IPCC for 1950–1989 and from the 2022 NDC synthesis report for 1990–2020; 2030 projections from NDCs; and the reduction scenarios from the AR6 Synthesis Report

    I have no idea what you are trying to imply by the term "stipulated".
  3. Can we still avoid 1.5 degrees C of global warming?

    Text under the Figure has spelled wrongly «NCDs, or national pledges» ... should have been: «NDCs, or national pledges».

    Why is the historical black graph before 1990 not solid?

    Maybe because the data is stipulated?

  4. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44


    Fine, but my money is on Zeke and the moderate, mainstream climate scientists.  I'm just not buying the theory of Simons and Hansen of an "aerosol termination shock."  

    As I say I'm not an expert, but I am a retired research engineer who worked with fusion scientists and high-energy-density physicists for 34 years, so I've seen a thing or two and this just seems too speculative to me.

  5. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Just Dean,

    The main scientific explainations for the extreme heat this year are: the start of El Nino, the volcano, aerosols and natural variation.  I think that in this thread you and others have posted data supporting the idea that the El Nino is too early to provide so much of an increase in temperature.  The volcano does not produce enough forcing to account for the increase in temperature and aerosols do not provide enough forcing for the observed temperatures.  I think "natural variation" is short hand for we don't know the cause.

    Obviously something has caused the extreme heat this year.  I think it probably is El Nino, the volcano or aerosols.  I think the data is not definative yet as to which is actually the cause.   Great scientists are divided on what they support.  We will have to wait two or three years.  During that time more data will become available.  That data will give us clues about what the true cause is.   I hope that it is El Nino or the volcano.  I fear it might be aerosols.  We need more data to decide.

  6. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44


    I'm not sure what I else I can say. I'm not an expert but I'm telling you that based on what I can find on the web, the consenus by climate scientists appears to be that Hunga-Tonga is not reponsible for our the spike in surface temperatures, contributes but is not a major factor. If you have not visited Dessler's post at The Climate Brink, I encourage you to do so. I'm sure he would still welcome questions or comments if either you or MA Rodger wish to discuss it with him.

    I referenced a paper by Stuart Jenkins @27. I don't have access to the paper but I found a detailed article about the paper at CarbonBrief . It has a nice plot of the projected increase in surface temperature as a function of time after the eruption. It causes a very slight increase over several years and then dissipates.

    This is the only study cited by Dessler that claims Hunga-Tonga added to heating. Two others actually believe it would cause slight cooling. Dessler claimed he was working on a peer-reviewed paper but I don't expect any surprises there. 

    I'm tapped out. I've gotten nothing else that I feel like I can contribute to this discussion.

  7. Can we still avoid 1.5 degrees C of global warming?

    "The report found that the net greenhouse gas emissions from human activity would need to be 43% lower by 2030 compared to 2019 to maintain a two-thirds chance of either meeting the long-term 1.5°C goal or only briefly overshooting it."

    This looks technically and economically possible to me as follows.

    "A new study by Stanford engineer Mark Jacobson and his team published in the journal Energy & Environmental Science calculates that the world would need to spend around $62 trillion to build up the wind, solar, and hydro power generating capacity to fully meet demand and completely replace fossil fuels. That looks like a huge number, even spread out across the 145 countries cited in the study. But after crunching the numbers, estimates show that countries would make the money back in cost-savings in a relatively short period of time: Between one to five years.",and%20completely%20replace%20fossil%20fuels.

    My view: To meet this goal of cutting emissions 43% by 2030, lets assume that we spend half the required 62 trillion, thus 30 trillion on renewables over the period 2023 - 2030 . That is 4.2 trillion dollars each year. Total global gdp (economic output) each year is currently about  $100 trillion, so 4.2 trillion is about 4% of global gdp per year.

    This looks a feasible amount of money to me if we really wanted. Its not going to impoverish the world. Its about what the USA spends on the military each year as a % of its own gdp. It would require cutting about 4% from other budgets including probably government spending and consumer goods spending. 4% is not a massive number.

    It would mean a huge engineering effort to transfer capacity into renewables but America and other countries did a similar sort of thing producing military hardware in WW2. And we are already partly there with renewables growing fast.

    Of course electricity generation is just one component but its the big issue, and the highest cost issue we need to address.

    It's really a question of whether the world can find the motivation to do all this. There are just several impediments in the way 1) The denialist campaign 2) Our brains are hardwired to priortise massive immediate threats like covid or wars, not insidious longer term problems like climate change even although they are a larger threat, 3) Lots of resistance to lifestyle change for various reasons, 4) politics.

    So I alternate between hope and despair.

  8. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Just Dean @27

    Regarding the experts allegedly blaming the warming this year (particularly July to October) on climate change plus a bit from el nino. This doesn't sound convincing to me. El Nino has barely even started so wouldnt have much effect (as others point out) , and greenhouse gas warming and its realted feedback mechanisms is a gradual process that wouldn't cause a sudden spike in warming in a few months of one year.

    The reduction in industrial aerosols from the new shipping rules in 2020 is also not a good explanation for this years warming.  The reduction in aerosols stared immediately in 2020 and increased from there, so You would expect it to have had a fairly immediate effect and an effect over the three years. Its hard to see why it would create a sudden warming spike three years later.

    I think MAR has a good explanation that the Tongan Volcano's aerosols have all fallen out of the atmosphere and remaining water vapour has thus caused a spike in warming. I did a google search a few days ago, and aerosols decrease over a period of a couple of years following a reverse exponential curve and water vapour can remain in the stratosphere for a couple of years. All it would need is for a large part of the water vapour to remain a little bit longer than the aerosols.

    But I think that the global warming trend will accelerate and may have already accelerated, due to the reduction in industrial aerosols and various feedback mechanisms, but it is not something we would be able to detect in just a couple of years temperatures. And its most likely going to be a gradual process, rather than a step change in just one year.

  9. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    MA Rodger,

    I looked at the video from Dessler. I don't understand why you cited that. That video is an explaination video cited by Dessler in his post from The Climate Brink where he concludes that Hunga-Tonga is "not reponsible for the blistering temperatures we're experiencing."  

    Or as his last sentence states, " If you’re sweating right now, don’t blame HT. Blame fossil fuels."

    Again, I think the jury is still out but I tend to trust the experts and from what I read most feel that Hunga Tonga is not repsonsible for this year's heat wave - Ref. From what I read an aerosol effect should play out over years not months and contribute a "baseline offset" if there is an effect. According to Stuart Jenkins, it is maybe on the order of 0.04 - 0.05 C. 




  10. Just how ‘Sapiens’ in the world of high CO2 concentrations?

    Michael @44 , I must modestly disagree with you.

    Yes, there is a real concern about the adverse effect of high local ambient CO2 levels in classrooms, submarines, and other enclosed spaces.   A perfectly valid concern, for health and intellectual performance (and most especially the performance of crew in a nuclear-armed submarine ! ).

    But please read again through the O.P.  ~ and note the panicky crescendo in the final few paragraphs.   [quote] "... we may end up intellectually a lot closer to plants."

    Sure, that was an expression of dramatic hyperbole ~ but hyperbole more fitted to a rally of Extinction Rebellion adherents, than to the sober annals of SkepticalScience.   Even in the comments thread, some seem to have taken that apocalyptic message seriously.   And I am thinking the propagandists at WUWT  would take it even further, as an example of them thar crazy Alarmists.

    But I am not so much interested in the final paragraph, as in the build-up evident in those lattermost paragraphs.   Even in the sly reference to D.Zappulla,2013  ~ a reference which actually discusses effects at CO2 ambients in the range 5,000 - 30,000 ppm.   Golly !

    The O.P. starts with matters of technical interest . . . but then gradually slides into unwarranted alarmism.   And it entirely fails to mention the human body's well-evolved compensation system [the kidneys].

    I do not wish to see the O.P. deleted  ~ but suggest a prominent CAUTION for the casual reader.


    As various people have remarked (thanks to all for your productive and tactful critique) this article's overall theme and especially conclusory speculation do not seem sufficiently supported by citations of directly pertinent literature. We're taking a closer look at the topic so as to formulate a responsive, fair and kindly means of remedy

    Update: article is now caveated with points of concern via editorial note.
    . --Skeptical Science Team

  11. Just how ‘Sapiens’ in the world of high CO2 concentrations?


    I think your concern is misplaced.

    This paper, from 2015 finds concentrations of CO2 in classrooms in New York at levels up to 1591 ppm.  They report teachers had more headaches the higher the concentration of carbon dioxide.  Obviously students are negatively affected.  Since background levels have increased since then you would expect classroom levels to increase.

    I taught in Florida.  Our classrooms are more crowded and often the air conditioning systems do not work.  I woud expect classroom conentrations to be hgher in Florida.  New York spends more on classroom maintenance than most states so I would expect New York data to be lower than most other states.

    If the external CO2 concentration increases that has a disproportionate on inclosed space concentrations.  If you are diluting the internal space with 300 ppm air the internal concentration stays lower than when you dilute the internal space with 450 ppm air.  Anywhere there are crowded buldings the concentration of CO2 becomes severely elevated.  Theatres, crowded offices, manufacturing areas all have elevated CO2.  Restaraunts that use gas stoves are severely affected.  

    The external air in cities is not 425 ppm.  This paper reports an hourly average of CO2 in Salt Lake City USA as high as 700 ppm in 2016.  I would expect other locations to be higher.

    Even 1000 ppm affects how people work and feel.    Most of us do not live on the top of Mauna Loa where the air is well mixed. (They delete the data when hgh CO2 air from the volcano mixes in).  You are looking at outside air.  The spaces where people work and live have increased carbon dioxide and exceed the limits that affect people.

  12. Just how ‘Sapiens’ in the world of high CO2 concentrations?

    A modest suggestion  [ not Modest Proposal ] :-

    In the absence of any information to the contrary during the past 8 days in this thread, I would like to suggest that this O.P. from 2014 be marked with a prominent note of Warning or Caution for readers.

    The O.P. starts well, by evidencing mild impairment of human intellectual function at an ambient (air) level of 1000 ppm of CO2.   Fortunately, a reversible impairment.

    But in the final 4 paragraphs, the O.P. implies that we humans should be alarmed, medically, at the prospect of a terrestrial atmospheric CO2 level of even 426ppm - 900ppm.    (The O.P. also links to the [bookish]  D.Zappullo~2013 ,  wherein is discussed major health problems from air CO2 of 5,000ppm - 30,000ppm.)

    However, in actuality,  an ambient CO2  426ppm-900ppm level would be swiftly compensated inside the body (within hours to days) through the activity of the kidneys which possess routine mechanisms to normalize total body acidity.   The adverse planetary effects of high CO2 are an entirely separate matter.

    SkS staff may wish to consider adding an up-front note, such as :-

    CAUTION : parts of this 2014 post are very misleading.


  13. Climate sensitivity is low

    Please note: the basic version of this rebuttal has been updated on November 12, 2023 and now includes an "at a glance“ section at the top. To learn more about these updates and how you can help with evaluating their effectiveness, please check out the accompanying blog post @

  14. Is Nuclear Energy the Answer?

    On Wednesday Nuscale cancelled their plant in Idaho.  That was the most advanced project of small modular reactors in the western world.  The price of the power was too high, even after the government spent over $600 million on the project.  It was supposed to be built on a location that used to have a fossil plant so water intakes and electrical connections to the grid were already built.

    Nuclear is too expensive, takes too long to build and there is not enough uranium.

  15. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Just Dean @22,

    My apologies for misreading your comment @20.

    The climatology community do not generally spend their time awaiting monthly global temperature anomalies and (as in the kerfuffle with the so-called 'hiatus' a decade back) tend to react to issues after they have arisen; and then not very fluently. So in that regard Jason Box is an oddity.

    Concerning the contribution of El Niño to 2023 global temperatures, it is true that there were stronger La Niña conditions in mid-2022 than there was in mid-1996 and particularly in mid-2014. Thus the change from a cooling La Niña would perhaps suggest more resulting warming in 2023. But the flip side of that is the La Niña conditions so far in 2023 being far weaker than 1997 & 2016 suggesting less resulting warming. (Note the 2009-10 El Niño also began from strong La Niña conditions in 2008.) The net effect for 2023 should then perhaps be 1997 or 2015-like. But they are not.

    Thus I would suggest there is ample evidence from the global temperature record to indicate something with perhaps even more warming impact on global temperatures than the coming La Niña.

    If the temperature rise (using ERA5 with assumed Nov/Dec 2023 anomalies as per @21) the global temperature rise through the first year and then the additional second year rise run as follows:-
    1996-97 ... +0.12ºC ... ... 1997-98 ... +0.19ºC
    2008-09 ... +0.13ºC ... ... 2009-10 ... +0.10ºC
    2014-15 ... +0.15ºC ... ... 2015-16 ... +0.18ºC
    2022-23 ... +0.30ºC ... ... 2023-24 ... +???ºC

    Perhaps it would be worth setting out the same data for was the most powerful El Niño of recent decades. This was overwhelmed by the El Chichón eruption of April 1982 which resulted in a cooling in 1982:-
    1981-82 ... -0.20ºC ... ... 1982-83 ... +0.19ºC

    So perhaps the Jan 2022 Hunga Tonga eruption and its water vapour is acting as a booster for 2023. (I mentioned satellite data @21 supporting this contention. See th 6 min video from Andrew Dessler here. It's now 3 months old.)

  16. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44


    The denialists will have to wait and see how warm 2024 is before they changne their posts!!

  17. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Just Dean:

    If you like Dr Hausfather's posts you will be in good hands.  I also like his detialed and timely posts.  As I said above, read as much as you can and focus on the people you think are most consistant.  There are currently several competing scientific explainations of the high temperatures in 2023.  More time will determine which is correct.

    I agree with MA Rodger that the current data does not explain the extraordinary high temperatures of 2023.  (I rarely post about temperatures on Skeptical Science any more because I usually agree with MA Rodger).  I hope he is correct that the unusual heat is caused by the volcano.  I fear that Hansen might be correct that aerosols have been obscuring more warming than is currently modeled.   Hausfather is a very skilled scientist and he thinks it might be an unusual El Nino.  This El Nino is following an unusually long La Nina period, perhaps that expalins the unusual change.  It could just be random natural variation (I doubt that).  I think the scientific literature supports all of these possibilities.

    In this case I expect that in two or three years the extraordinary heat this year will be explained.  If is is an unusual El Nino we should know in 2024 or 2025.  If it was the volcano the temperatures in 2025 should return to the previous trend.  If it is aerosols they will stay elevated.  This is an unusually short time to determine a scientific explaination.  The data might be muddled and we will need another few years to determine the best answer.

    This is how science advances!!  Competing hypothesis are tested against the data.  People initially take sides.   As more data becomes available one hypothesis is more supported by the new data.  Most people accept the most supported hypothesis.

  18. Skeptical Science New Research for Week #45 2023

    In all the papers above, if there is one that should not be ignored, it is this one : 

    Good Practices and Common Pitfalls in Climate Time Series Changepoint Techniques: A Review, Lund et al., Journal of Climate Open Access pdf 10.1175/jcli-d-22-0954.1

    Good read to all.

  19. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Back in 2016, I created this graphic regarding the spike in global temperatures, and how the denial industry would respond.

    Search replace 2016


    With 2023 showing such a high temperature anomaly, you can bet that all the web sites and reports that claim "no warming since..." will be running an exercise similar to this:

    Search replace 2023

  20. SkS Analogy 26 - Earth's Beating Hearts

    Paul@4, that is an interesting observation for our current era: a relationship between the sun and the ice. But if the polar ice caps were to disappear, the sun crossing the equator twice per year would no longer have the same effect.

  21. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    MA Rodger,

    If you read my previous comment closely, you will see that I understand we are in the first year of an El Nino event. I am indeed comparing 2023 to 2015 or 1997. 

    If you look at the global temperature series referenced in Zeke's July 26 CarbonBrief article, you will saw-tooth like structures for both the 1998 and 2016 El Nino events. The total temperature excursion over the two years was about 0.3 C, with each year adding about 0.15 C.  I realize that 2023 is extraordinary and might be closer to a jump of 0.2 or 0.25 C  but we need to see how this year and 2024 play out.  To quote Zeke from his 10/31 post on The Climate Brink, "It remains to be seen if we will see more exceptional warmth in the latter part of this year and early next as the El Nino event peaks or if this El Nino is behaving differently – potentially contributing more warming early on due to the rapid transition out of unusually persistent La Nina conditions – than we’ve seen in past events."

    We are observers in an unfortunate global warming experiment. We will need wait to see how it unfolds. To my earlier point to Michael, Zeke is trying his best to interpret this in real time, and allowing us to look over his shoulder, basically giving updates on a weekly or biweekly basis. I am not aware of any other climate scientist that is sharing insight that frequently. Between Zeke, Mann and Hansen, I find Zeke to be the most moderate, consistent and coolheaded. Yes, I'm a fan.

  22. SkS Analogy 26 - Earth's Beating Hearts

    So the beating heart is the annual solar cycle, caused by the Earth's tilt as it orbits the sun? Crossing the equator twice per year. 

  23. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Just Dean @20.

    It is not correct to make a comparison of 2023 with El Niño years 1998 & 2016. We are in the first year of a 2023/24 El Niño and the earlier ones were 1997/98 and 2015/16. 2023 is not the El Niño year in which the temperatures jump.

    (Using ERA5 numbers), if we assume the October anomalies coutinue for Nov/Dec, 2023 would show a record year averaging +0.16ºC above all previous years. 1998 & 2016 saw similar +0.15ºC & +0.18ºC respectively. But 2023 is not another 1998 or 2016. We would have to wait for 2024 to make a comparison with previous El Niño years. And the coming El Niño is not looking anything like 1998 or 2016. It is forecast to be "moderate El Niño event", so more like 2010.

    That is why 2023 is being described as "Staggering. Unnerving. Mind-Boggling. Absolutely gobsmackingly bananas." The big question, which is yet to be answered, is 'Why?'

    2023 temps drivers

    You'll be familiar with this graphic if you follow Jason Box. It well-explains the temperature rise 2014-2023 but it does not show anything that would explain the "staggering, unnerving, mind-boggling & absolutely gobsmackingly bananas" temperatures we've seen over the last five months.

    (If you want to see how bananas, have a play on the UoMaine Climate Reanalyser and compare 2023 with previous years, then blank off 2016-23 and repeat for 'pre-El Niño' 2015. And again for 1997.)

    My suggestion as to 'Why?' is that the Jan 2022 Hunga Tonga eruption which was exceptionally large and being sub-ocean blew large amounts of both SO2 and H2O into the stratosphere. These two would cancel each other out so the rather chilly 2022/23 winter (globally) with the SO2 marginally more powerful. But that SO2 has dropped out now and the remaining H2O is still there providing us the bananas. If this is the situation (& there is satellite data showing SO2 dropping out quicker than the H2O), the bananas do thankfully have a shelf-life.

  24. SkS Analogy 26 - Earth's Beating Hearts

    groovimus @2:

    Congratulations. Your second post at SkS, and  you've provided two incredibly bad arguments in a single paragraph.

    First, you're making an "argument from incredulity" I can't believe that people are still making "I can't believe" types of arguments these days. [See how that works?]

    Second, you're making an "it's only a trace" argument. Usually people that are making an "it's only a trace" argument are doing it with respect to CO2 concentrations. At least we should give you some points for originality - for making it about the mass of humans vs. the mass of the earth - but you're still only scoring 2-3 points out of 100. If you were really creative, you'd go onto the CO2 is a trace gas thread and tell us how the mass of CO2 is sooo small in comparison to the mass of the earth, instead of the usual comparison with the mass of the atmosphere alone. It would still be a completely bogus argument, but boy oh boy could you really throw around some huge ratios!

    Also, you never did go back to follow up your first SkS comment, where you completely failed to provide any argument why anyone should listen to John F Clauser (the subject of the post you were supposed to be commenting on). All you had there was ad hominem rants and insults.

  25. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44


    I basically read everything Zeke write's including every post at CarbonBrief,, and his October 13th NYTimes article and some of his recent peer-reviewed journal articles.

    Zeke has basically been giving his readers and followers a play by play of this, "Staggering. Unnerving. Mind-Boggling. Absolutely gobsmackingly bananas" year.

    You may want to remember that we need to wait until 2023 is over before we can plot the average temperature for the year by all the different sources, on the global temperature series .  To me it appears that 2023 will be high right in line with the two year duration of the El Ninos of 1998 and 2016 where basically the average temperatures jumped by 0.3 C.  

    I don't I think I need to read anymore of Zeke's work but maybe you want to consider it. 

  26. SkS Analogy 26 - Earth's Beating Hearts

    Kudos bringing the planetary mass into view. Now let's look at the human biomass. In terms of planetary mass it is 5 x 10^-14 of the planetary mass. Such numbers trigger a what's going on here headsmack. Are we really proposing that a biomass can develop the sun amplifying machinery to influence the temperature of a mass 2 x 10^13  larger?

  27. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44


    I think the explaination of current heat caused by " El Nino, uptick in 11-year solar cycle, Hunga-Tonga and reduction in aerosols due to 2020 phaseout of sulphur dioxide" is not very satisfying. 

    The El Nino has just started.  Usually the effect of El Nino is felt most at the end of the year and the year following.  That means we are just now feeeling the El Nino effect.  In addition, the current El Nino is described as moderately strong, not extremely strong source.  To me that means that only a little of the extrordinary heat of the past 4 months could be attributed to El Nino.  Dr. Zeke Hausfather here primarily attributes the current extreme record temperatures to El Nino.  I doubt the El Nino has contributed so much heat so early in the cycle.  We will see how much hotter next year is.  I think El Nino contributes less than 0.1 C.  

    The solar cycle only contributes about 0.2 C to warming from the top of the cycle to the bottom.  While the cycle has increased a lot this year, it is still not peaking out.  The solar cycle is not much different from earlier record years.  This contribution is also less than 0.1 C.

    The volcano is harder to evaluate.  Most volcanoes cool the surface but this one shot a bunch of water into the Stratosphere.  Since that has not happened before it is hard to estimate.  I think the volcano contributes less than 0.1 C.  

    October was 0.4 C above the previous record year which had a much stronger El Nino, September was 0.5 C above record, August 0.3 C, July 0.43 C higher.  These records are usually broken by hundredths of a degree.  The past years had stronger El Ninos and the solar cycle was comparable.  

    Hausfather's estimates of all the forcings do not add up to 0.5C for September.  Hansen has been saying for decades that aerosols reduce temperature much more than the models indicate.  I fear that Hansen is correct and the unaccounted for warming is coming mostly from the reduction in aerosols.  This is due primarily to the change in marine fuels with some coming from polllution controls in China.

    If the record heat is caused primarily by the reduction in aerosols it will be permanent.  Next year will be hotter because of the  El Nino.   Future years will build off a new base that is about 0.4 C higher than it was three years ago.  Hansen predicted before this year that 1.5 C would be exceeded before 2030.  If this year is above 1.5 C becasue of aerosol reduction than by 2030 it is very likely all years will be above 1.5 C and Hansen will be correct.  If the volcanoes effects have been underestimated than after next year the temerature should go down for a few years.

    Pray that Hansen is incorrect and the volcano caused this years extraordinary temperatures.

    Keep strongly in mnd that Drs Mann, Hansen and Hausfather are way more informed about these matters than individuals who post on the internet, including me.  I recommend you try to read as many of their postings as possible to determine who you think is being the most consistent.

  28. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Your perspective on the Keeling curve and the challenges ahead is thought-provoking. Acknowledging the current upward acceleration in CO2 concentrations and the potential difficulty in even stabilizing them paints a stark reality. Your caution about assuming we can achieve more than stabilization is a call to recognize the Herculean task at hand, balancing hopeful trends with the resistance to necessary change. It's a sobering reminder to plan for the worst while striving for the best, given the uncertainties and the collective will required for significant global shifts,

  29. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Absolutely, the discussion around the warming in the pipeline is a nuanced one. It's refreshing to see your optimism amid acknowledging the Herculean task of decarbonization. The pace of clean tech deployment is impressive, and while the road ahead is long and challenging, your belief in reaching the destination is encouraging. Balancing awareness of the challenges without painting it as a lost cause is key. It's a delicate dance, but a necessary one for fostering both awareness and hope in the face of daunting environmental issues.

  30. wilddouglascounty at 22:25 PM on 9 November 2023
    SkS Analogy 26 - Earth's Beating Hearts

    This is wonderful. Thanks for connecting the dots in ways I have never considered.

  31. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Michael@13, I'm not sure I agree or understand your statement about Zeke's explanations for the recent warming as "pretty weak."  He has given it the most thorough treatment that I have seen both at The Climate Brink and at CarbonBrief .  Factors include El Nino, uptick in 11-year solar cycle, Hunga-Tonga and reduction in aerosols due to 2020 phaseout of sulphur dioxide.

  32. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    This Hansen et al (2023) paper was pre-published back in January and did result in a bit of discussion here at SkS. And there was supposed to be a second paper specifically on SLR.

    Hansen et al rattle through a pile of stuff, some of which I would agree has merit and some which I find difficult to accept, some very difficult. The high ECS is one of the very difficult ones. (Perhaps the point that the big part of the difference between high ECS values and the IPCC's most likely value ECS=3ºC, [something the IPCC tend not to identify preferring a range of values as in AR6 Fig1.16]: the difference is due to warming that follows the forcing by a century or more. That time-lag is one of the reasons the ECS estimates are not better nailed down and still has its 'fat tail' . It also would give mankind a fighting chance of dodging it.)

    SLR is certainly a big subject of concern. It is a long-term problem, multi-century. The equilibrium position for a +1.5ºC is perhaps 3m and the threat of setting Greenland into unstoppable meltdown at higher levels of warming would triple that. I do tend to get irked by the SLR by 2100 being the sole subject of discussion.

    Of course, predictions of that 2100 SLR being massive (5m) is one of Hansen's foibles. The worry is, I think, specific to Antarctica and it is a genuine worry. But to achieve 5m by 2100 would need massive numbers of icebergs bobbing around in the southern oceans and result in global cooling. And there is also the awkward point for climatologists that increased snowfall over Greenland/Antarctica could provide a significant reversal of SLR.

    The final issue raised by Hansen et al (2023) is the impact of the reduction of aerosols from our falling SO2 emissions. Quantifying the impact of SO2 emissions is not entirely global a thing, so emissions in, say, China may induce more cooling than, say, Europe. But that said, global SO2 emissions data I identify tends to be way out-of-date. The most recent is this one from a Green Peace publication. This shows the reduction in SO2 is well in hand over the last decade. And the CERES data showing EEI does show a drop in albedo (yellow trace in the 2nd graphic) through that period. My own view of these CERES numbers is that they include a lot of bog-standard AGW-feedback-at-work.

    SO2 emissions 2005-19

    CERES TOA fluxes

    There is also the last 5 months of crazy global temperatures (so post-dating Hansen et al's pre-publication). I don't see these as being sign of things to come. I'd suggest it is casued by the January 2022 Hunga Tonga eruption which threw both SO2 and H2O into the stratosphere, the cooling SO2 dropping out leaving the warming H2O to do its thing before eventually it too dropping out.

    And the in-the-pipeline thing. Climatology is/has-been saying we need to halve CO2 emissions b 2030, and following the point of net zero in mid century we enter a century-plus of net-negative CO2 emissions. That would see all emissions 2008 to year-of-net-zero removed by human hand and stored away safely. So that is on top of the natural draw-down of CO2 into the oceans. And if we don't do that, it will not be from ignorance of the situation.

  33. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    I believe Hansen has to be right to the extent there will be more warming in the pipeline due to sulphate aerosols reducing, over the immediate short term future. Aerosols cause a cooling effect so if you cut them you must get a warming effect. However its a question of how much warming would be in the pipeline, and I went looking and found this a few days ago: "Cutting air pollution would not cause ‘near-term spike’ in global warming"

    The study appears to say that if sulphate aerosols were all cut to zero immediately you would get a significant spike in warming lasting about a decade or so, but if they are phased out over several decades (which is the far more realistic scenario) additional warming  would be zero or quite small.

    We have had a couple of hot years and significant heatwaves and Hansens argument appears to be this relates to reduced aerosols from shipping (?). While I have huge respect for Hansen, I struggle to believe something like that would cause enough warming, and haven't seen anyone come up with numbers on it.

    Manns concern appears to be that people will give up on mitigation if they begin to believe a lot of warming is already baked into the system or that we are already doomed. And IMO hes right. Therefore its important to be accurate about exactly how much warming is baked into the system and not exaggerate and speculate unnecessarily.

  34. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    I don't think Hansen is worried about thousands of years in the future.  He has been saying for decades that aerosols are reflecting a lot of energy back into space, cooling the planet.  Reducing fossil fuel use reduces aerosols.  The loss of aerosols causes rapid warming.  Hansen projects that 1.5C will be exceeded by 2030 and 2.0 C will be exceeded by 2050.  He is concerned about changes that will occur while people alive now are still around, about 100 years.  He is concerned about multimeter sea level rise by 2100.  If Hansen is correct about aerosols the next 30 years will have substantial extra heating.

    I respect Zeke and Mann but their explainations for the extreme heat the past 6 months are pretty weak.  While the current temperatures are inside the error bars for the models, the temperature this year is extraordianrily hot comnpared to all previous years.  I note that the IPCC generally emphasizes what a consensus of scientists think is the minimum amount of change in the climate and temperature.  That means that a majority of scientists  think it will be worse than the IPCC projections.

    The scientists who project damages substantially exceeding the IPCC reports are in the minority.  It is very concerning to  me that they exist at all.  Especially since the last 6 months have been so hot and next year is projected to be even hotter.  El Nino does not usually strongly affect temperature until the end of the year.

    I agree that "it's important to communicate the incredible challenges we face but without instilling in people's minds the idea it's already a lost cause."  But politicians still are not taking action seriously.

    What is the IPCC defination of "consensus".  It has to be a lot higher than 50%.  Is it 80%, 90%?  They must have it written down somewhere.

  35. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Evan... Yes, we can agree more or less on everything you've stated there. My point is, that is different from the warming in the pipeline discussion.

    I will say, though, my perspective tends to be more optimistic than yours. I see quite a lot happening toward decarbonizing society. As you say, it is a Herculean task but the pace at which clean technologies are being deployed is also impressive. It's not yet enough. We have a long hard road ahead in the coming decades. But I think we're going to get there.

    I believe it's important to communicate the incredible challenges we face but without instilling in people's minds the idea it's already a lost cause. 

    On the warming in the pipeline issue, I think Zeke and Andrew get it. If Hansen is discussing millennial level warming in the pipeline as steady concentrations, it's important science to understand, but functionally irrelevant to the challenge of the coming decades.

  36. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Rob@8, can we agree on the following. If the Keeling curve (i.e., plot of CO2 concentration vs year) does no better than level off, then we have warming in the pipeline. Currently the CO2 concentration is accelerating upwards (these are the words that Ralph Keeling himself uses). It is possible that we do many wonderful things to control our emissions and do no better than to simply stop the upward acceleration. In that case, we still have a disastrous situation.

    Even if we do much, much better than to stop the upward acceleration, the next big challenge is to stabilize CO2 concentrations. If we do not better than that, then we have warming in the pipeline.

    My point is simply that it is prudent to assume that we will never do better than to stabilize atmospheric CO2 concentrations, because getting to that point will require a Herculean task. Yes, there are hopeful trends, but there is also a lot of resistance in the world to the kind of change needed to reach Net Zero emissions. These trends could quickly slow down.

    I understand the arguments you and others are making. I just don't believe we have the collective will to do what is needed to make the model assumptions come true. Hence, I will continue to urge people to plan as though current atmospheric concentrations represent our commitment level.

  37. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Dean... Seems the buried lede is here: "... Hansen’s assumptions will not happen. We are not going to keep atmospheric carbon dioxide and other greenhouse gases fixed for thousands of years. We will definitely stop burning fossil fuels in somewhere between a few decades to a few centuries and the concentration of greenhouse gases in our atmosphere will decline after that."  

    My point here is, you seem to be going off topic talking about the rate of increasing CO2 concentrations (@7) rather than discussing warming in the pipeline.

  38. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Rob@8, Zeke and Andrew Dessler take issue with how Hansen is defining "warming in the pipeline." Basically, he is assuming constant atmospheric concentrations and then he is holding it there for millenia to allow slow feedback mechanisms to kick in, Ref. 5/22/23 . 

    Evan@7, If you wait to see a significant decrease of the rate of increase of CO2, it will be too late. You won't see that until we have made significant progress in reducing man made emissions, see projected CO2 ppm vs emission scenarios, Climate change:Atmospheric Carbon Dioxide .

  39. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Evan @7... I believe the rate of increase in CO2 concentrations is a different issue than warming in the pipeline, though. Mann (and Hausfather) are taking issue with Hansen's claim there would potentially be decades of warming even after bringing CO2 emissions under control.

  40. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Dean@6, I hope you're correct. Personally, I will only change my view when there is a statistically significant decrease of the rate of increase of CO2, because ultimately the three facts you cite do not determine how the environment will respond. Collectively they are an important component, but only one component that affects the rate of accumulation of CO2 in the atmosphere. Noting that our emissions are only about 4% of natural emissions, we only have to affect natural emissions, or sinks, by a small amount to overwhelm our efforts to control the rate of accumulation of CO2.

    I am not really arguing against you, but using this forum to remind the readers of other factors involved. I respect that the facts you're quoting are accurate and come from reliable sources. So I am merely noting that they only represent one piece of the puzzle, and noting that we may still be a bit optimistic about how the natural world will respond to what we have already done and continue to do. I think Hansen differs from other because he has a different view of how sensitive the natural world is to our actions.

  41. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Evan@5, I understand. I prefer to look to the moderate voices in almost any circumstance. To quote Zeke, I am cautiously optimistic about our future and getting to net zero. We have bent the curve on global emissions and according to the IEA and others, e.g. Rystad energy, we may well hit peak emissons this year or at least by 2025.

    I follow the progress of the U.S. electrical sector emissions. Here are three positive facts about our progress.


    1. Renewable generation surpassed coal and nuclear in the U.S. electric power sector in 2022, link.

    2. Add nuclear to the renewables and emission-free carbon sources account for almost 40% of the generation in the U.S.

    3. The specific carbon intensity of the US electrical sector has decreased by 40% between 2000 and 2022, falling from 650 kg/MWh to 390 MWh.

  42. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Dean@4, When the IPCC was just being formed, it was Hansen in 1988 who was sounding the alarm. Hansen has always been at the forefront of climate predictions, preceding the IPCC in his assessment of how severe the climate crisis is and will likely become. The IPCC has always represented a baseline assessment of where we're heading, and not necessrily an accurate assessment of just how bad things could get.

    But let's find common agreement, because I've read the paper by Hausfather (read here) where he shows that temperatures will be frozen if we reach Net 0 emissions. I understand the arguments you're making.; But with CO2 concentrations rising at 2.5 ppm/year, and the state of world affairs leaning ever more to the right, it will be a long long time before I hold any hope for reaching Net 0 emissions. I will continue to encourage others to view our warming commitment as corresponding to the current level of CO2 in the atmosphere. Anything beyond that is contingent on global actions that are still struggling in their infancy. Yes, we have lots of talk and agreements, yes wind power has been increasing, but with CO2 rising at 2.5 ppm/year, apparently we have yet to sufficiently impress the natural world that we're doing enough.

  43. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Evan, It is not just Mann that disagrees with Hansen. I believe that Hansen holds the minority position here. Both Zeke and Mann reference the IPCC special report on 1.5C that warming will cease when we get to net zero emissions.  To me, the IPCC represents the consensus thinking. There is a recent paper by Dvorak and Armour that reaches bascially the same conclusion, Ref. , and adresses the aerosol effect.

    If you follow Zeke at and/or X, he has addressed directly Hansen's pipeline paper and his high estimate of climate sensitivity. Also, Zeke's latest analysis of record breaking temperatures relative to the multimodel averages can be found at

  44. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Rob, that does not make Michael Mann correct. "No warming in the pipeline is a theoretical concept that requires us to completely restructure society. Hansen cannot be easily dismissed by simply citing a different researcher. I live my life assuming that we are committed to the level of warming reflected by the current CO2 concentration. I think this is a reasonable approach. I hope I'm wrong and that Michael Mann is correct. But I tend to side with Hansen.

  45. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Evan... Michael Mann is in pretty firm disagreement with Hansen on this issue. 

  46. 2023 SkS Weekly Climate Change & Global Warming News Roundup #44

    Hausfather's recent paper (read here) suggests there is no "warming in the pipeline" should we reach net-zero emissions. Hansen's new paper cited in the above article (read here) uses the very provocative title, "Global warming in the pipeline". Given that one of the leading voices in the climate community (i.e., Hansen) releases a paper now with this provocative title, should give pause to the idea that the warming is in our hands and under our control.

    It is likely that the environmental system is far more sensitive than we are willing to admit.

  47. Increasing melting of West Antarctic ice shelves may be unavoidable

    Not to mention, that if you want to postulate that geothermal heat is cause of recent WA melt, then you need to show a mechanism that can suddenly increase the heat flux over a wide area is a very short space of time. Not actually possible with conductive geothermal heat. In short, those fluxes have been present for a very long time.

  48. Increasing melting of West Antarctic ice shelves may be unavoidable

    David-acct @ 1:

    Oh, my. A paper that shows that there is a geothermal heat flux of 285 milliwatts/m2 at a site in the West Antarctic ice sheet. And 105 milliwatts/m2 flowing up through the ice sheet!

    Your "complete analysis" is no such thing. This sort of argument has been discussed previously here in comments on more than one thread. Try reading some of the comments adjacent to these ones:

    Is Antarctica losing or gaining ice?

    Why do glaciers lose ice?

  49. Increasing melting of West Antarctic ice shelves may be unavoidable

    Surprising that there was no mention of the geothermal activity in West Antarctica .  The article only mentions warming seas as if global warming was the primary cause of the West antarctica sea ice melting.

    Far better to provide a more complete analysis


  50. Just how ‘Sapiens’ in the world of high CO2 concentrations?

    Thanks, Res01 @41  (and forgive my perhaps over-courteous usage of a capital letter for your moniker ~ that is simply my customary literary style).

    Time is precious in this modern age . . . and so, no  ,  have not read the OP's Robertson  paper [the link showed as Page Not Found]  nor the Stumm  paper [unlinked].    Yes, it is quick to read a paper's Extract; and where that is insufficiently informative, still it is usually possible to skim through the body/conclusion of a paper to identify the salient points.   But it's even better if one can "Cut To The Chase".

    All the same, there is so much information "out there" on the internet ~ that the SkS  website staff have created a Comments Policy which requests all commenters to respect readers' time . . . by giving a sufficiently detailed relevant description/summary of (linked) citations.  Whether the citation/link is an actual scientific paper or simply a journalistic article.

    # That request applies in Spades, to video links (even if the video is only 5 minutes long).   As you know, videos can be a great time-waster.   That's why a summary of the video's message and significance can be a great help to the flow of the discussion happening in the thread here.

    Res01 ~  I particularly ask for your deeper discussion of the essential science of this topic of "CO2 impact" on human (and animal) bodies.  That is because I fear that a major mistake is being raised (and I would be pleased to be corrected if I am wrong about that).

    Evolution has designed the body to operate at a specific set point (or very narrow range)  of acidity/pH.   You can temporarily disturb that pH by hyperventilating (to raise the pH)  or by re-breathing into the classic paper bag (to lower the pH).   But in the long run, it is the kidney (as mentioned earlier)  which maintains the body's day-by-day acidity level.   Renal function is vital !

    And it is (as yet) unclear to me if Robertson / Stumm / and other sources, have made allowance for those basic facts of physiology.   Are they making a giant blunder ~ or am I making a blundering assessment of their warnings?   Please discuss.

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