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Unforced variations: Mar 2020

Filed under: — group @ 1 March 2020

This month’s open thread for climate science topics.

151 Responses to “Unforced variations: Mar 2020”

  1. 51

    year dT CO2
    1850 -0.239 284.7
    1851 -0.004 284.9
    1852 -0.137 285
    1853 -0.326 285.1
    1854 -0.125 285.3
    1855 -0.522 285.4
    1856 -0.587 285.6
    1857 -0.58 285.7
    1858 -0.555 285.9
    1859 -0.193 286.1
    1860 -0.649 286.2
    1861 -0.516 286.4
    1862 -0.756 286.5
    1863 -0.275 286.6
    1864 -0.825 286.8
    1865 -0.453 286.9
    1866 -0.44 287
    1867 -0.603 287.1
    1868 -0.424 287.2
    1869 -0.393 287.4
    1870 -0.549 287.5
    1871 -0.659 287.7
    1872 -0.355 287.9
    1873 -0.384 288.1
    1874 -0.483 288.4
    1875 -0.832 288.7
    1876 -0.497 289
    1877 -0.252 289.4
    1878 -0.023 289.8
    1879 -0.553 290.2
    1880 -0.363 290.7
    1881 -0.44 291.2
    1882 -0.336 291.7
    1883 -0.617 292.1
    1884 -0.724 292.6
    1885 -0.693 293
    1886 -0.532 293.3
    1887 -0.578 293.6
    1888 -0.594 293.8
    1889 -0.276 294
    1890 -0.446 294.2
    1891 -0.536 294.3
    1892 -0.633 294.5
    1893 -0.708 294.6
    1894 -0.484 294.7
    1895 -0.574 294.8
    1896 -0.395 294.9
    1897 -0.31 295
    1898 -0.396 295.2
    1899 -0.329 295.5
    1900 -0.194 295.8
    1901 -0.157 296.1
    1902 -0.398 296.5
    1903 -0.432 296.8
    1904 -0.533 297.2
    1905 -0.405 297.6
    1906 -0.184 298.1
    1907 -0.606 298.5
    1908 -0.457 298.9
    1909 -0.423 299.3
    1910 -0.333 299.7
    1911 -0.415 300.1
    1912 -0.434 300.4
    1913 -0.306 300.8
    1914 -0.063 301.1
    1915 -0.06 301.4
    1916 -0.346 301.7
    1917 -0.652 302.1
    1918 -0.417 302.4
    1919 -0.275 302.7
    1920 -0.262 303
    1921 -0.099 303.4
    1922 -0.248 303.8
    1923 -0.263 304.1
    1924 -0.314 304.5
    1925 -0.212 305
    1926 -0.064 305.4
    1927 -0.223 305.8
    1928 -0.146 306.3
    1929 -0.469 306.8
    1930 -0.108 307.2
    1931 -0.072 307.7
    1932 -0.076 308.2
    1933 -0.317 308.6
    1934 -0.025 309
    1935 -0.163 309.4
    1936 -0.117 309.8
    1937 -0.032 310
    1938 0.152 310.2
    1939 -0.002 310.3
    1940 -0.041 310.4
    1941 -0.029 310.4
    1942 -0.046 310.3
    1943 0.01 310.2
    1944 0.107 310.1
    1945 -0.119 310.1
    1946 -0.078 310.1
    1947 -0.005 310.2
    1948 0 310.3
    1949 -0.108 310.5
    1950 -0.301 310.7
    1951 -0.107 311.1
    1952 -0.063 311.5
    1953 0.129 311.9
    1954 -0.145 312.4
    1955 -0.192 313
    1956 -0.426 313.6
    1957 -0.078 314.2
    1958 0.041 314.9
    1959 0.019 315.97
    1960 -0.068 316.91
    1961 0.039 317.64
    1962 0.027 318.45
    1963 0.024 318.99
    1964 -0.283 319.62
    1965 -0.233 320.04
    1966 -0.132 321.38
    1967 -0.09 322.16
    1968 -0.207 323.04
    1969 -0.114 324.62
    1970 -0.054 325.68
    1971 -0.202 326.32
    1972 -0.225 327.45
    1973 0.138 329.68
    1974 -0.278 330.18
    1975 -0.065 331.11
    1976 -0.354 332.04
    1977 0.082 333.83
    1978 -0.047 335.4
    1979 0.039 336.84
    1980 0.125 338.75
    1981 0.3 340.11
    1982 -0.02 341.45
    1983 0.317 343.05
    1984 -0.047 344.65
    1985 -0.042 346.12
    1986 0.106 347.42
    1987 0.264 349.19
    1988 0.361 351.57
    1989 0.234 353.12
    1990 0.49 354.39
    1991 0.38 355.61
    1992 0.094 356.45
    1993 0.177 357.1
    1994 0.331 358.83
    1995 0.57 360.82
    1996 0.228 362.61
    1997 0.49 363.73
    1998 0.841 366.7
    1999 0.556 368.38
    2000 0.474 369.55
    2001 0.668 371.14
    2002 0.762 373.28
    2003 0.758 375.8
    2004 0.66 377.52
    2005 0.863 379.8
    2006 0.805 381.9
    2007 0.895 383.79
    2008 0.682 385.6
    2009 0.731 387.43
    2010 0.914 389.9
    2011 0.707 391.65
    2012 0.761 393.85
    2013 0.826 396.52
    2014 0.866 398.65
    2015 1.151 400.83
    2016 1.292 404.24
    2017 1.12 406.55
    2018 0.941 408.52
    2019 1.158 411.44

  2. 52

    Gavin et al.,

    Is it possible to post a chart in here? Or would it have to be a link to a chart?

    [Response: put in a link. I can embed it if asked. – gavin]

  3. 53
  4. 54
    Al Bundy says:

    With Covid-19 dropping carbon emissions do we have an accidental experiment that will help pin down aerosols?

    Yo, Mike! Yeah, I was pretty sure that MAR is an Al. I’m just jealous cuz he’s a real Al and I’m just an immitation.

  5. 55
    David B. Benson says:

    Yet more evidence for the so-called Clovis Comet:
    https://m.phys.org/news/2020-03-evidence-cosmic-impact-destruction-world.html

    From Syria!

  6. 56
  7. 57
    zebra says:

    #40 EGS,

    A quick look at some of your references indicates that you are seriously misunderstanding what they conclude. Why don’t you pick a couple and explain your reasoning/interpretation in more detail, and then we might be able to help you out more efficiently than trying to do the whole list.

    I’m just curious, though, about you saying that you were “directed to this site”. Who directed you? Was it a graduate advisor, or an employer, or what?

  8. 58

    #47, AB–

    At AB: MAR is another Al

    AB: who has never identified himself as “Al”. So why are you tossing strange illogicals?

    MAR posts at Open Mind using his proper name (or at least *a* proper name), the first half of which is indeed ‘Al.’ It’s the ‘A’ in ‘MAR.’ Presumably Mike knows that from Open Mind, and casually cross-identified Al/MAR.

    (At a tangent, there are a couple of Mikes/mikes over there, and I will confess that I sometimes feel a bit confused as to which is which.)

  9. 59
    Bob Loblaw says:

    jb @ 25 said:

    Sorry, I forgot the most important one:

    “If people suffer misfortune, its their own fault and they deserve what they get.
    Unless it’s one of us.

    You forgot the most important part of that:

    …Unless it’s one of us. In which case it’s the fault of government interference”

  10. 60
    Bob Loblaw says:

    Re: EGS comment @ 40.

    Just a note to the unwary. EGS has already been peddling this poppycock over at Skeptical Science:

    https://skepticalscience.com/argument.php?a=206#134809

  11. 61
    nigelj says:

    BPL @37 you have given KIA a comprehensive rebuttal, a real shellacking. Hopefully some if it might sink in but I’m not optimistic. Hes a slow learner.

  12. 62
    Killian says:

    44
    nigelj says:
    6 Mar 2020 at 4:34 PM

    Killian says “When I say simplicity, shutting down the vast majority of industrial production, solves our problems, maybe one or two of you can begin to wrap your head around just how rapidly things can change. And it’s the *only* way things can rapidly change. Thanks, virus, for the sad but effective proof of concept.”

    Yes stopping most of industrial production will certainly dramatically reduce CO2 levels and quickly. We didn’t need covid 19 to show us what is obvious.

    Please, for once in your silly-headed life stop lying. You have never believed climate could be rapidly effected by simplification and have always claimed simplification would take LONGER than tech responses… becuase you keep yourself intentinally ignorant on these issues.

    It will also cause massive supply shortages, and bring us to our knees. This is equally obvious.

    No, child, it would not. Shed yourself of your self-inlficted, intentional ignorance of very simple knowledge and read something about controlled vs uncontrolled simplification. I know knowing before your run your mouth is antithetical to your existence, but one can hope.

    And do note, being brought to our knees is already happening in an uncontrolled unfolding global disaster. But you are right, a controlled response to wind down on our own terms, not a pandemics, would be worse.

    [edit]

  13. 63
    MA Rodger says:

    Barton Paul Levenson @49,
    I mentioned up-thread that Polvani et al (2020) had been subject to corrections which are incorporated into the paper linked here. The comment by EGS @40 (which you challenge) was referencing the uncorrected paper.

    The substance of the corrections is to take account of AGW being the product of ‘net’ forcings (rather than ‘positive’ forcings) which Polvani et al initially ignored. Thus their modelling showed global temperature increases 1950-2005 reduced by 33% the if they restricted the model-forcing from OCS (‘ozone depleting substances’ comprising a whole list of GHGs fron CFC-11 down to CHBr) to the 1950 value. These OCS are considered to comprise just 20% of the actual ‘positive’ forcing for the period 1950-2005, a forcing thus absent from their model. With such absence, Polvani et al found the effect considerably greater than 20% with the global ΔT reduced by 33%.
    But the ‘net’ forcing responsible for AGW is significantly smaller than the ‘positive’ forcing. Strangely Polvani et al were unable to enumerate the level of ‘negative’ forcing used in their modelling. Using IPCC AR5 AII values, as a proportion of the ‘net’ forcing 1950-2005, OCS constitutes 30% making the global Polvani et al 33% finding entirely unremarkable.
    In the uncorrected paper (and the corrected paper) Polvani et al cite Hansen et al (2005) ‘Efficacy of climate forcings’ to support/explain their ‘remarkable’ global result but ignore Richardson et al (2019) which rather pulls the rug from under their bold interpretation of Hansen et al (2005), this an added a mark of the poor scholarship evident in Polvani et al (2020).
    The corrected text thus concentrates on the Arctic effect of removing the OCS forcings.

    “At the same time, anthropogenic aerosols are believed to have produced a considerable, yet highly uncertain, negative RF. Without the large cancellation from aerosols the relative contribution of ODS to the total forced Arctic climate change would be smaller. However, irrespective of aerosols, the absolute contribution of ODS—nearly 0.8 °C of warming and 0.7 × 106 km2 of September sea ice loss over only 50 years—is remarkably large.’”

    (This Arctic effect of OCS does jog some memory for me of poleward pollution transport [which OCS entirely comprises] but the jogging isn’t enough to remember the literature source.)

  14. 64
    EGS says:

    I am, of course, just an educated outsider to this field, but its strikes me as significant that these other greenhouse gasses seem to be written off as anthropogenic climate forcing gasses by an undue preoccupation with the alleged climate sensitivity to C02, which may well be a confusion of cause for effect. The paleoclimactic record shows that C02 always lagged warming and then modestly reinforced a warmer climate by tempering temperature swings as a GHG. Are there different anthropogenic influences since industrialization, yes, as my post has made plain, but the mistake may have been made in confusing the higher rate of warming in the 20th century with the higher C02 concentrations that came with the warming following the Little Ice Age (as oceans and land released C02) in the 1850s and which happened to coincide with industrialization and so included sizable anthropogenic C02 emissions. Why rising C02 concentrations with what I presume were still linear longwave radiative forcings and water amplification feedbacks did not lead to a greater rise in temperature before the 1970s has never been explained convincingly, nor has why rising C02 concentrations suddenly led to a spike in the rate of warming after the 1970s. Why was there such a modest rate of warming between 1850 and 1980? Why the spike and higher rates of warming since the 1980s? Could it have been due to the dramatic increase in atmospheric concentrations of really potent GHGs since the 1970s that a growing body of peer reviewed research indicates have been underestimated, understudied, and underreported. Why resort to convoluted arguments about cloudcover, aerosols, volcanism, natural variability and lower sun irradiance to explain the lower than expected pre-1970s warming rate when a perfectly plausible explanation for the spike in the post 1970s warming may be right in the air? Why is it not these other greenhouse gasses? That would seem to be the scientific way of tackling this problem. Rule that out first and then come up with other plausible explanations. Similar arguments that explained the lower rate of warming before 1980 now seem to proliferate about why the rate of warming didn’t continue to rise as predicted by models in 2000-2014. Of course the warming has picked up since then, I am not disputing this, nor am I even disputing in any way anthropogenic global warming. If anthropogenic global warming is a problem, as I believe it is, then why are we going out of our way to claim that C02+water vapor is the main forcing and amplification mechanism, even as the empirical evidence of the C02 forcing+water vapor amplification theory is so thin—no significant tropical upper tropospheric temperature anomaly has been found by either satellites or radiosondes despite 40 years of study, and no longer-term trend in increased tropospheric water vapor has been found despite the increase in warming since the 1980s. Indeed, the longer term trend has been if anything slightly downward, suggesting a greater role of cloudcover and precipitation than the models assume. Another advantage of giving halocarbons, methane, nitrous oxide, black carbon, and tropospheric ozone a closer look is that they can simultaneously explain stratospheric ozone thinning, usually high levels of warming in the poles, the dramatic stratospheric cooling seen over the poles, and the bulk of arctic sea ice loss. Why is that an implausible explanation for these phenomena from the perspective of climate scientists?

  15. 65
    MA Rodger says:

    EGS @64,
    You tell us there is “a growing body of peer reviewed research [which] indicates” that “the dramatic increase in atmospheric concentrations of really potent GHGs since the 1970s [that is GHGs other than CO2] … have been underestimated, understudied, and underreported.”
    Perhaps you could reference some of this alleged “growing body of peer reviewed research” which you tell us is ‘indicative’ of this alleged ‘underestimation, understudying and underreporting’; this so we can better understand what you mean.

    However, I would suggest that what you really mean is to ask “Why is it [‘it’ being the driver of AGW] not these other greenhouse gasses [‘other’ meaning ‘other than CO2’]?”
    I assume you find this difficult to ask properly as you appear to strongly feel you have gained an understanding about AGW which has eluded anyone-&-everyone working within climatology, an understanding which, unlike the evidence-based science of climatology, conforms to the denialist dictum “Anything but CO2!!”

    But please do consider either presenting the evidence for your grand assertions or consider asking for an explanation as to why your theorising doesn’t fit the evidence. I would add that the many errors you make within your comment @64 could be corrected but doing so would probably not be helpful for you at this juncture.

  16. 66
    nigelj says:

    Killian @62, I disagree. I have posted a brief response on the FR thread.

  17. 67
    Ray Ladbury says:

    EGS,
    Pray, what makes you say that these greenhouse gasses have been ignored? Their greenhouse potential has been considered. Papers have recommended preferentially tackling these GHGs first. Perhaps this is a matter of your ignorance rather than of anything actually being ignored.

  18. 68
    EGS says:

    Just to be clear, I was talking about tropical tropospheric water vapor, not water vapor in lower and upper latitudes, which correlate very nicely with rising temperature as expected. The study that I looked at on the tropics is by G. Partridge et al. https://link.springer.com/article/10.1007/s00704-009-0117-x on the reanalysis of NCEP data as well as the discussion hosted by Rob van Dorland that included guest blogs by Steve Sherwood and Carl Mears on the tropical tropospheric temperature anomaly. https://www.mwenb.nl/the-missing-tropical-hot-spot/. There has also been a discussion about this topic by Steve Sherwood on this blog http://www.realclimate.org/index.php/archives/2005/08/the-tropical-lapse-rate-quandary/ with a discussion. I’m not sure that this is even important to my point questioning the exclusive focus on CO2 as the primary driver of post 1980 anthropogenic warming. I think the perspective of economic history could be valuable for periodizing when changes in land use and farming practices, use of industrial solvents and transition to fuels changed significantly in the late 20th century.
    Even if Polvani et al. have had to walk back a few of their claims, I think these findings are still significant and I will quote from the revisions which M.D. Rodger pointed out, albeit in an unfortunately hostile tone implying that I have a “preciously held answer.” I have no such answer otherwise I wouldn’t have bothered to go on either the SKS or this site to raise my questions:

    The revised abstract to the Polvani “Letter” in Nature Climate Change:

    “While the dominant role of carbon dioxide is undisputed, another important set of anthropogenic GHGs was also being emitted over the second half of the twentieth century: ozone-depleting substances (ODS). These compounds, in addition to causing the ozone hole over Antarctica, have long been recognized as powerful GHGs. However, their contribution to Arctic warming has not been quantified. We do so here by analysing ensembles of climate model integrations specifically designed for this purpose, spanning the period 1955–2005 when atmospheric concentrations of ODS increased rapidly. We show that, when ODS are kept fixed, forced Arctic surface warming and forced sea-ice loss are only half as large as when ODS are allowed to increase. We also demonstrate that the large impact of ODS on the Arctic occurs primarily via direct radiative warming, not via ozone depletion. Our findings reveal a substantial contribution of ODS to recent Arctic warming, and highlight the importance of the Montreal Protocol as a major climate change-mitigation treaty.”

    This suggests that IPCC AR5 may be outdated. How can you still have a “dominant role of CO2” and suddenly discover that other trace gases measured in parts per billion have had such a major impact on climate over the last 40 years? What would happen to the models if updated realistic estimates of the net forcings of tropospheric ozone, nitrous oxide, methane were included?.

  19. 69
    nigelj says:

    EGS @64, have you ever encountered the novel idea of having several separate paragraphs?

  20. 70
    nigelj says:

    EGS @64 packs every possible piece of denialist nonsense into one massive paragraph. Sounds like Victor version 2.0.

    “Why was there such a modest rate of warming between 1850 and 1980? Why the spike and higher rates of warming since the 1980s? Could it have been due to the dramatic increase in atmospheric concentrations of really potent GHGs since the 1970s that a growing body of peer reviewed research indicates have been underestimated, understudied, and underreported. Why resort to convoluted arguments about cloudcover, aerosols, volcanism, natural variability and lower sun irradiance to explain the lower than expected pre-1970s warming rate when a perfectly plausible explanation for the spike in the post 1970s warming may be right in the air? Why is it not these other greenhouse gasses? ”

    The modest rate of warming prior to the 1970s was because there was not that much accumulation of CO2 at that stage, and the effects from aerosols. Its not a case of arguing those things, its what the EVIDENCE shows.

    And its notable that since the use of ozone depleting CFCs have been reduced since the Montreal protocol in 1989, the warming trend has not changed which should be telling you these chemicals are not a large factor in warming. The other chemicals you mention are strong greenhouse gases but total quantities are not large enough to be that significant even when added together. People have done the numbers on this material, maybe you should research it first before jumping to conclusions.

  21. 71

    #56, DBB–

    David, that’s disappointing. I’m no expert on this, but a blocking event–of which there are quite a few different flavors–does not necessarily mean no usable wind for power production. There’s a big difference between what happens at jet stream altitudes and what happens at the surface. I spent some time searching to try and find more information on what the relationship may be between blocking events and wind at the heights relevant to wind power generation, and didn’t come up with much, beyond the hints that blocking events can be associated with persistent storminess in some locations, or persistent precipitation.

    But finally, as a ‘smell test’ for the idea that blocking events mean low winds, I went to the Climate Reanalyser and looked at 10-meter wind speeds for the months of July and August in western Europe. (That, of course, is the place and time for one of the most notorious heat waves on record, and the event cited in your article.)

    For July, anomalies across the region were quite unremarkable–high anomalies across most of the UK, and Portugal, as well as a chunk of Mediterranean Sea west of Italy, with normal-to-very-slightly negative anomalies–by which I mean no lower than -0.3 m/s–across most of the rest of central Europe, including France, which was the epicenter of the heat wave mortality.

    https://climatereanalyzer.org/reanalysis/monthly_maps/

    In August, one sees a couple of strongly becalmed areas out in the Atlantic, as well as a weaker one in the Mediterranean off the eastern Spanish coast, but most of central and western Europe is still pretty close to the norms for the month.

    And scanning the patterns for some other months that year, I have to say that there’s very little indication that the blocking experienced in July and August did much, if anything, to suppress 10-m windspeed. The maps before and after the blocking events don’t look radically different from July and August, as far as my unpracticed eye can tell. (The most “different” one to my eye is December 2003, which features some huge positive anomalies, extending north-to-south from Scandinavia to Northern Africa across a wide swathe of central Europe. But even that month didn’t show a consistent pattern spanning the whole of Europe, which at least indicates that Europe is large enough that you never see a windspeed pattern affecting the entire continent.)

    All that said, I must admit that the tool is less than ideal; monthly means are a blunt instrument at best. But hey, if you’ve got some more ‘on-point’ data, I’d be interested to see it. And if anyone has more information on this interesting question, I’d love to hear it.

    Turning away from the meteorological details, of course there’s no denying what you put as your conclusion:

    So wind power requires backup.

    That’s never been at issue. The questions are, how much, and what sort? I don’t think the answer to the first is “weeks” (as has been claimed), and I do think that the best answer to the second is “a variety of generation and storage options.” Diversity of supply is generally our friend.

  22. 72
    jgnfld says:

    “Why is that an implausible explanation for these phenomena from the perspective of climate scientists?”

    You ask a lot of questions. Now I’ll ask a few. What, precisely, makes your ideas MORE plausible than currently accepted notions? What parts of the currently accepted notions can you clearly falsify with good data? What special expertise and specific data do you bring? What makes you think that professionals haven’t already thought extensively about your “insights” and considered the data on them closely already?

    Here’s another: Does Tom Brady go to the local sports bar for useful coaching advice?

  23. 73

    EGS 64: The paleoclimactic record shows that C02 always lagged warming

    BPL: Look again: http://bartonlevenson.com/Lag.html

    BTW, paragraphs breaks are your friend.

  24. 74
    Nemesis says:

    Hehe, my 23 years old foster-daughter knows 100% what the bells ring about climate heating, while my 55 years old neighbour claims that the winters in Germany have ALWAYS been like 2019/2020 (and he is surely not alone with that sick claim, sheeples are many, that’s just the nature of sheeples) xD I LOVE these denierz and lukewarmerz as they will put funny money capitalism to an ultimate end, they work for my dreams in a weired sense, harr harr 38) Now go on piling up numberz, hoping, that funny capitalism will solve all problems oh so beautifully, while I lay back again and watch the Uncorruptible Cooking Pot of Nature unfold.

    Cheerz,
    Nemesis

  25. 75
    MA Rodger says:

    RSS TLT has posted a February anomaly of +1.01ºC, up from January’s +0.88ºC, the increase pretty-much all down to an increase in NH mid-latitudes which has actually flown off their chart (which shows to +1.5ºC when the anomaly for 25.0N to 60.0N comes in at +1.61ºC).
    As with UAH TLT, in RSS TLT Feb 2020 is the second-warmest February on record, and this without any significant El-Niño-boost.
    The warmest Febrarys in RSS now run 2016 (+1.23ºC), 2020 (+1.01ºC), 1998 (+0.73ºC), 2017 (+0.72ºC), 2010 (+0.68ºC), 2019 (+0.67ºC), 2015 (+0.56ºC), 2018 (+0.52ºC), 2007 (+0.50ºC), 2002 (+0.49ºC) & 2005 (+0.47ºC).
    Feb 2020 sits 3rd in the RSS TLT all-month anomaly record behind the El-Niño-boosted months Feb & Mar 2016 (as per UAH).
    The start to 2020 in RSS averages +0.94ºC, 2nd warmest on record after El-Niño-boosted 2016 (+1.06ºC) with 3rd spot 2010 (+0.71ºC), =4th 2017 & 2019 (+0.68ºC) and 6th 1998 (+0.67ºC).

  26. 76
    MA Rodger says:

    EGS @68,
    You say of Polvani et al (2020) that you “quote from the revisions” and that it has a “revised abstract.” Yet it is not so much a quote you present, as you present the entirety of the abstract. In what way has this abstract been revised? I think you’ll find it has not been!!
    ❶ So in what way do you think this ‘abstract that remains unrevised’ by the walk back of Polvani et al “suggests that IPCC AR5 may be outdated”?
    ❷ Why would you question the “dominant role of CO2” when the reference you wield to support your question, in its revised form, says “the largest RF is associated with CO2, and it is three times larger than the RF from ODS, over the 1955–2005 period” and the actual text you present (the unrevised abstract) begins ” the dominant role of carbon dioxide is undisputed”?
    ❸ What is the basis of these “updated realistic estimates of the net forcings of tropospheric ozone, nitrous oxide, methane “ you talk of?

    You say you have no “preciously-held answer” but, given the questioning of your grand theorising down this thread (and elsewhere), so far you seem to provide no answers of any form, other than you adherence to that “preciously-held answer.”

  27. 77
    nigelj says:

    https://iopscience.iop.org/article/10.1088/1748-9326/ab6b37

    Research study: “Global warming to increase violent crime in the United States”

  28. 78

    EGS 64: why are we going out of our way to claim that C02+water vapor is the main forcing and amplification mechanism,

    BPL: Because of the physics. Please pick up a book on atmosphere physics and read through it, and work all the problems. Houghton’s “The Physics of Atmospheres” is a good one.

    EGS: even as the empirical evidence of the C02 forcing+water vapor amplification theory is so thin

    BPL: Google “Clausius-Clapeyron.” Water-vapor feedback has been well established since the 19th century.

  29. 79

    EGS 68: my point questioning the exclusive focus on CO2 as the primary driver of post 1980 anthropogenic warming.

    BPL: Do you know what analysis of variance is?

  30. 80
    Nemesis says:

    @nigelj, #77

    “Research study: “Global warming to increase violent crime in the United States” ”

    Yeah, the cooking pot of nature is such a bloody beauty, no science, no discussions, no blather at all, just bloody eating and beeing eaten. I love clear, uncomplicated, indisputable facts more than ever in these funny times of wasted discussions, smoke and mirrors 8)

  31. 81
    Nemesis says:

    @nigelj, #70

    ” EGS @64 packs every possible piece of denialist nonsense into one massive paragraph. Sounds like Victor version 2.0.”

    So why the hell waste time on that kinda shit again and again and again? Entertainment?

  32. 82
  33. 83
    EGS says:

    Are we supposed to believe that it was only in 1979 (according to Barton Levenson’s data, above) when CO2 concentrations reached the mark of 336.84 ppmv that CO2+water vapor first induced an increased rate of warming? A net increase in CO2 concentrations of 50 ppm+water vapor amplification feedbacks between 1850 and 1978 (from 284.7 to 335.4 ppmv) had little or no effect on the rate of warming over more than 100 years?

    No, it was only after we reached the magical mark of 336.84 ppm that the rate of warming increased. Steep increases in anthropogenic emissions of N20, CH4, CFCs, other halons, tropospheric 03, and black carbon since the 1970s had very little to do with this sudden increased rate of warming starting in the 1980s?

    Look at the trends in N20, CH4 and 03 since the 1970s. Look at the close relationship between the mole fraction of anthropogenic atmospheric N20 and the steep increase in agricultural nitrate application between 1960 and 1985. https://www.atmos-chem-phys.net/17/4539/2017/acp-17-4539-2017.pdf.

    Look at the steady increases in atmospheric CH4 concentrations since the 1960s, growing by an estimated 13ppbv per year between 1962 and 1979. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JD094iD15p18279.

    Look at ozone emissions that also (coincidentally?) reached peak levels in urban areas of the industrial world in the 1960 and 70s and that were only gradually reduced over the following three decades through smog control measures only to rise dramatically in more recent years in China and elsewhere https://eos.org/features/urbanization-air-pollution-now. And now the study by Polvani showing that much of the arctic warming between 1955 and 2005 was due to CFCs and other ozone depleting chemical radiative forcing.

    I was disturbed when I read the blog posts by Steve Sherwood and Carl Mears hosted by Rob van Dorland on the tropical upper tropospheric hot spot. Neither could offer a convincing rebuttal to the insufferably arrogant and justifiably reviled John Christy. Their retort to his reading of the ground, radiosonde, and satellite temperature data was we need to put the data in a blender so we can finally detect a missing warming signal (Mears) or that the temperature data cannot be trusted and should be adjusted in line with model predictions—oh and anyway, it doesn’t matter (Sherwood). If you think the educated public is too dim to understand what that means, I think you’re fooling yourself.

    I’m really not your enemy. I’m a tenured professor at a very progressive New England college, a lifelong Democrat, secular humanist, NYT reader, NPR sustaining member, and a former college Greenpeace activist who walks or cycles almost everywhere. I’m genuinely worried about anthropogenic global warming but fear that we’ve lost sight of the main current drivers of this problem from the IPCC’s undue obsession with one greenhouse molecule and that we’ve dropped the ball on all of the others. And the policies we’ve implemented, both here and in Europe, are failing to address it. Miserably.

    I understand that climate is an immensely complicated stochastic system, and I admire the brains and energy that has gone into modeling it—I’m vastly too stupid to do this kind of science! But model predictions should not warp our perceptions of reality; they should be tools to understand that reality and come up with credible predictions of the future.

  34. 84
    EGS says:

    MA Rodger:

    I grew up in Mormon country, so I’m a little sensitive to theological cajoling. I’m accused of being “denialist,” and unbeliever, and what I say is heresy. I’m to be excommunicated from the climate discussion.

    Has this sort of browbeating been effective since Jim Hansen gave his Congressional testimony in 1988? Have some climate scientists perhaps oversold their product a tad, maybe cried wolf a few too many times over the last 30 years? Might a bit more humility and modesty be in order?

    And what has the preoccupation with “carbon” over the last 20 years of environmental policy really delivered, pray tell?

    Exhibit A: The shift to diesel vehicles in the EU. While no doubt saving some energy and money per km driven and emitting less C02, these vehicles generated far more N20, O3, and fine particulates than engines running on gasoline, propane, methane, or pure hydrogen. In addition to being orders of magnitude more potent greenhouse gasses than C02, the diesel particulates are proven carcinogens, and N2O and O3 are destructive to human and animal cardio-pulmonary health. Worldwide, diesel exhausts are estimated to cause 38,000 premature deaths each year https://www.newscientist.com/article/2131067-diesel-fumes-lead-to-thousands-more-deaths-than- thought/.

    Exhibit B: the German decision to phase out nuclear power in 2011 and the introduction of feed-in tariffs for wind and solar power. It led to chaos in the electrical grid that forced Germany to import dirtier electricity (and nuclear elec. power) from neighbors and to expand lignite mining and lignite-fired electrical power, something that actually increased its carbon footprint and led to missing its “climate targets.” https://www.bloomberg.com/graphics/2018-germany-emissions/. Net negative “feel good” measures?

    What if the EUR 500 billion spent on this nonsense had been invested to remove all diesel vehicles from European streets? Or eliminate home heating oil and bunker fuel in Europe’s container shipping fleet? Or drastically cut intra-European air travel by high taxes and rail subsidies? Or by drastically cutting N20 and CH4 emissions from Europe’s huge and massively oversubsidized farm and livestock sector?

    That would have put a big dent in future warming while saving thousands of lives. Yes, it felt good to go nuclear-free, to go solar (in a climate with 4.4 average sunlight hours per day), to go 100 km on 4 liters of diesel.

    We’re now repeating this nonsense with electric vehicles, the great hope of some carbon crusaders. What’s the net effect on warming of retooling the entire automotive sector and producing these vehicles? Think of the fossil fuels used in mining, refining and transporting the metals, producing the chemicals and glass, electronics, and in the assembly. And what is their net contribution to reducing anthropogenic warming if most of the charging electricity ultimately comes from coal or natural gas? Yet another net negative “feel good” measure, I predict

    Why not pick the low-hanging climate fruit now to demonstrate to the public how deep cuts in known extremely potent and damaging GHG can reduce climate risk and improve human health? That injects a message of hope and pragmatic possibilities as we improve our still rudimentary understanding of the world’s climate system, enhance the credibility of climate science, and come up with intelligent energy strategies.

    But MA Rodger, since you’ve been high up on AGW mountain, you must have all the answers already. What might they be?

  35. 85
    Ralph says:

    New sport? Got a live one.

    Please (pedantic yes) but it’s CO2 not C zero 2

    64 EGS says: 8 Mar 2020

    “The paleoclimactic record shows that C02 always lagged warming…”

    Except when it didn’t.

    “Why rising C02 concentrations with what I presume were still linear longwave radiative forcings and water amplification feedbacks did not lead to a greater rise in temperature before the 1970s has never been explained convincingly, nor has why rising C02 concentrations suddenly led to a spike in the rate of warming after the 1970s.”

    All those kinds of ‘issues’ have been explained ad nauseam and convincingly.

    “Why was there such a modest rate of warming between 1850 and 1980? Why the spike and higher rates of warming since the 1980s?”

    Been explained ad nauseum.

    “Could it have been due to the dramatic increase in atmospheric concentrations of really potent GHGs since the 1970s that a growing body of peer reviewed research indicates have been underestimated, understudied, and under reported.”

    No.

    ” Why resort to convoluted arguments about cloudcover, aerosols, volcanism, natural variability and lower sun irradiance to explain the lower than expected pre-1970s warming rate when a perfectly plausible explanation for the spike in the post 1970s warming may be right in the air? Why is it not these other greenhouse gasses? That would seem to be the scientific way of tackling this problem. Rule that out first and then come up with other plausible explanations.”

    Oh brother my brother!

    Reminds me of all the times I used to see people on news sites and forums asking questions like : “Why all this talk about CO2 and Green house gases? Why haven’t the scientists looked at the most likely cause – the Sun?”

    Dear EGS,

    Go read all the material here and don’t say another thing or ask another question (anywhere) until you have finished it all.
    https://history.aip.org/climate/index.htm

    Then read of all this material, try to understand it, do cross reference research about issues raised difficult to understand, note the definitions of and what words mean and get yourself up to speed. And never again presume you know something the scientists don’t or might have missed.

    The Synthesis Report (SYR) of the IPCC Fifth Assessment Report (AR5) provides an overview of the state of knowledge concerning the science of climate change, emphasizing new results since the publication of the IPCC Fourth Assessment Report (AR4) in 2007.
    https://www.ipcc.ch/report/ar5/syr/

    They aren’t stupid EGS. And they were all trained to be good scientists too. That’s why, well, they’re Scientists.

  36. 86

    EGS, #83 & 84–

    …the IPCC’s undue obsession with one greenhouse molecule…

    Assuming what you wish to prove. The IPCC has taken pains to investigate and quantify the roles of all GHGs, including those about which you are concerned.

    Are we supposed to believe that it was only in 1979 (according to Barton Levenson’s data, above) when CO2 concentrations reached the mark of 336.84 ppmv that CO2+water vapor first induced an increased rate of warming? A net increase in CO2 concentrations of 50 ppm+water vapor amplification feedbacks between 1850 and 1978 (from 284.7 to 335.4 ppmv) had little or no effect on the rate of warming over more than 100 years?

    No, and no. It’s previously been shown here and elsewhere that the correlation between CO2 and temperature is quite good. And you’re misreading the stats BPL presented–there’s no drastic change in relation between CO2 and temps at 1979, as for some reason you seem to think. Here–if the link works–is that relationship, graphed just now by me. (CO2 data copy-pasted from BPL’s comment above, temperature data ditto, then scaled up by 80x and offset by 315 to align with CO2.)

    https://tinyurl.com/CO2-HadCRUt-temps

    (That’s where the comparison with denialist Victor comes in: you’re both asserting a lack of correlation that does not obtain–though a tad ironically, you seem to be saying that there’s not enough warming in the early 20th century, while his claim was that there was too much.)

    Now, here’s a mixed message, in spades:

    I understand that climate is an immensely complicated stochastic system, and I admire the brains and energy that has gone into modeling it—I’m vastly too stupid to do this kind of science! But model predictions should not warp our perceptions of reality; they should be tools to understand that reality and come up with credible predictions of the future.

    Shorter version: I’m “too stupid” to do the work, but so much smarter than the pros that I can see their work is completely “warped.” Not a model of coherent utterance, IMHO.

    We’re now repeating this nonsense with electric vehicles, the great hope of some carbon crusaders. What’s the net effect on warming of retooling the entire automotive sector and producing these vehicles? Think of the fossil fuels used in mining, refining and transporting the metals, producing the chemicals and glass, electronics, and in the assembly.

    First, EVs aren’t “the great hope of some carbon crusaders.” They are just a tool to decarbonize transportation–albeit one that seems poised for takeoff in deployment. Second, most of the inputs you mention are equally necessary under the status quo. There is a modest increase in embodied emissions due to the battery pack, but that’s more than offset by the lifetime savings in direct emissions.

    https://www.carbonbrief.org/factcheck-how-electric-vehicles-help-to-tackle-climate-change

    And what is their net contribution to reducing anthropogenic warming if most of the charging electricity ultimately comes from coal or natural gas?

    The best candidate for “great hope of carbon crusaders” is in fact the decarbonization of the power grid–a process clearly well underway. In the parts of the world where automobile use is most intensive, coal is rapidly being pushed off the power grid, and gas is next.

    And one last point about EVs. Has it escaped your attention that ICEs are also sources of N2O (‘NOX’), not to mention numerous other lung-irritating and disease-causing chemicals? So deploying EVs at scale should in fact address your stated concern about air quality to a very considerable degree. Why, then, the hostility?

    Finally, you want to ‘pick low-hanging fruit.’ That’s been proposed multiple times, actually, in various forms. Random examples:

    https://www.c2es.org/content/short-lived-climate-pollutants/

    https://www.popsci.com/turning-methane-into-carbon/

    But what, exactly, would you advocate to reduce methane, N2O, et al?

    (Note that policy proposals are more appropriate for the Forced Responses thread, so if you’re willing to get concrete about your ideas, it should probably be done over there.)

  37. 87
    MA Rodger says:

    GISTEMP has posted a February anomaly of +1.26ºC, up from January’s +1.17ºC.
    As with the TLT anomalies, in GISTEMP Feb 2020 is the second-warmest February on record, and this without any significant El-Niño-boost (although the boost is usually less in surface records).
    The warmest Februarys in GISTEMP now run 2016 (+1.37ºC), 2020 (+1.026ºC), 2017 (+1.13ºC), 2019 (+0.95ºC), 2015 (+0.90ºC), 1998 (+0.87ºC), 2018 (+0.85ºC), 2010 (+0.84ºC), 2002 & 1995 (both +0.79ºC).
    Feb 2020 sits 3rd in the GISTEMP all-month anomaly record behind the El-Niño-boosted months Feb & Mar 2016 (as per UAH & RSS).
    The start to 2020 in GISTEMP averages +1.22ºC, 2nd warmest on record after the El-Niño-boosted 2016 (+1.27ºC) with 3rd spot 2017 (+1.08ºC), 4th 2019 (+0.94ºC), 4th 2015 (+0.88ºC) and 6th 2005 (+0.86ºC).

  38. 88
  39. 89
    nigelj says:

    EGS @83

    “Are we supposed to believe that it was only in 1979 (according to Barton Levenson’s data, above) when CO2 concentrations reached the mark of 336.84 ppmv that CO2+water vapor first induced an increased rate of warming? A net increase in CO2 concentrations of 50 ppm+water vapor amplification feedbacks between 1850 and 1978 (from 284.7 to 335.4 ppmv) had little or no effect on the rate of warming over more than 100 years?”

    The answer to your questions is yes to the extent that CO2 (and water vapour feedback)had only a relatively limited effect on warming before 1978. The following is my understanding of the situation and it needs a brief history. CO2 did have some effect on the warming rate prior to 1978, because its a greenhouse gas and there was warming prior to the 1978, particularly around the 1920 – 1940 period (refer any long term temperature data set). But the atmospheric concentrations of CO2 were relatively low over the period of 1910 – 1940 and aerosols in the emissions cancelled some of this warming. Most of the warming from 1910 – 1940 was caused by solar activity, reduced volcanic activity and ocean cycles. Studies typically attribute about 25% of the warming to CO2.

    After the 1940s the atmospheric concentration of C02 had increased, however much was from heavy coal burning after WW2 and the aerosol content in coal is high and is believed to have cancelled the warming effect of CO2 particularly over land, hence the flat land temperatures after WW2. There’s very good evidence for the effects of aerosols easily enough googled.

    By the late 1970’s a couple of things had happened. Firstly CO2 concentrations were getting relatively substantial, enough to 1) have a powerful warming effect and 2) overcome much of the effect of aerosols from the coal, and secondly, filter devices were fitted to coal fired electricity generation to filter out sulphate aerosols. These two things taken together caused warming to resume over land after about 1978 in quite an abrupt fashion.

    So the warming spike after 1978 was nothing to do with ozone depleting chemicals or nitrogen oxides etc, and was simply due to the increasing cumulative concentration of CO2 and the reduction in aerosols. Ozone depleting chemicals cannot explain the warming spike after 1978 because these were not suddenly introduced in the late 1970’s and in fact use had been gradually increasing for decades prior to this.

    I’m a lay person. You are educated so should be able to see the significance of the history. In addition scientists have looked at the warming effects and concentrations of gases like nitrogen oxides and CFCs and methane, concluded CO2 is causing most of the warming, working from first principles and the evidence, although these other gases are certainly significant. This sort of material is discussed in the IPCC reports which are fee online and full of references to the associated research papers.

  40. 90
    MA Rodger says:

    EGS @83/84,

    Do you really expect folk here to take you seriously given your continued performance.

    If somebody was trying to propose that rising levels of atmospheric N2O are more of a threat than CO2, they would be rather silly using a reference to support their grand theory if it start off like the one you picked, Prokopiou et al (2017) which begins by saying “N2O is currently the third most important anthropogenic greenhouse gas in terms of radiative forcing.”

    And the prime candidates you choose to replace CO2 – well they are the second and third biggest contributors to AGW but if anybody sensible examined the atmospheric levels of N2O (plotted out here) and CH4 (plotted out here), there is no great increase to be seen that could possibly provide a reason for the post-1970 global warming. You need CO2 forcing for that, and also those exotic GHGs (CFCs, HCFCs & HFCs) which began to add some serious climate forcings from the 1960s but only until the mid 1990s (eg as graphed here). A plot of the increases in climate forcing and the responsible gases is graphed out here (usually 2 clicks to ‘download your attachment’). Over the last 20 years CO2 has been responsible for 80% of the increase in climate forcing. The science is well founded.

    So if you want, continue on and give us a good laugh. Or alternatively put your brain in gear and take on board what the science is saying.

  41. 91
    Al Bundy says:

    Nemesis: my 55 years old neighbour claims that the winters in Germany have ALWAYS been like 2019/2020

    AB: humans are wired to sense temperature change more than temperature itself. Our minds think that a cold spell is a cold spell even if a current cold spell is warmer than yesteryear’s “typical”. Add in that one’s tolerance for cold decreases as one ages and your neighbor’s beliefs arise.

    And yes, the comment sections are largely entertainment.
    _____

    EGS,
    Interesting that you claim CO2 always lags temperature and then deduce that since temperature is currently lagging CO2 there can be little or no connection between the two.

    Erroneous axioms spoil the intellectual soup.

  42. 92
    EGS says:

    nigelj@70
    “And its notable that since the use of ozone depleting CFCs have been reduced since the Montreal protocol in 1989, the warming trend has not changed which should be telling you these chemicals are not a large factor in warming. The other chemicals you mention are strong greenhouse gases but total quantities are not large enough to be that significant even when added together. People have done the numbers on this material, maybe you should research it first before jumping to conclusions.”

    Jumping to conclusions? Atmospheric CFC concentrations have barely fallen at all. CFC-12 concentrations only plateaued around 2000 and have barely fallen off since. Have a look at NOAA’s data: https://www.esrl.noaa.gov/gmd/hats/about/cfc.html

    At most it looks like < 1-2% overall reduction in atmospheric concentrations in the most abundant CFCs over the last 30 years. Does that represent big reductions in the 100-year global warming potential of these gases?

  43. 93
    EGS says:

    nigelj@70
    “The modest rate of warming prior to the 1970s was because there was not that much accumulation of CO2 at that stage, and the effects from aerosols. Its not a case of arguing those things, its what the EVIDENCE shows.”

    But at lower concentrations CO2 accumulations are assumed to have more linear forcings that then become logarithmic as the concentrations build and the longwave bands saturate, so I presume the radiative forcing for each ppm increase + water amplification feedbacks would have been stronger in the 19th century than in the 20th century as concentrations began to approach 400 ppm, would they not?

    And what EVIDENCE is there that cooling anthropogenic aerosols suddenly cleared out of the atmosphere in the late 1970s and 1980s?

    According to Leibesperger et al. (2012) SOX and NOX emissions peaked in the US in the 1980s and 1990s, not before. And these peaks and later declines were counterbalanced by steady rises in these aerosols elsewhere on the globe up to 2000 and beyond. Primary organic aerosols began to rise in the US in the 1970s after declining since the 1950s, but elsewhere they were on a steady rise until peaking around the year 2000. https://www.atmos-chem-phys.net/12/3333/2012/acp-12-3333-2012.pdf

    Volcanos? The biggest volcanic eruptions of the 19th and 20th century were Tambora (1815), Krakatoa (1883), Santa Maria (1902), Katmai (1912), Quizapu (1932) and Pinatubo (1991) and had temperature reducing effects of 0.1-0.5 C that lasted 1-5 years. https://www.sciencedirect.com/science/article/abs/pii/0377027381900743

    This doesn’t support a narrative that warming could have been much suppressed over most of the 19th century. In the 20th century only the first 15 years, the early 1930s and early 1990s experienced significant volcanic cooling. It’s doubtful that volcanic aerosols could have been much of a factor in the relatively cooler decades of the 1940s-70s.

    The 1995 Mitchell et al. Nature paper that everyone likes to cite is based on GCM runs adding sulfate aerosols to better match the climate record. https://www.nature.com/articles/376501a0.pdf I presume that’s your EVIDENCE.

  44. 94
    Nemesis says:

    @Al Bundy, #91

    ” humans are wired to sense temperature change more than temperature itself. Our minds think that a cold spell is a cold spell even if a current cold spell is warmer than yesteryear’s “typical”. Add in that one’s tolerance for cold decreases as one ages and your neighbor’s beliefs arise.”

    No. We had NO winter 2019/2020 whatsoever, no snow, no frost, no nothing, so every idiot can see/feel that something is terribly wrong here^^ My neighbour is nothing but a sick ignorant who just does not WANT to ADMIT climate heating, he’s just the classic denier sheeple.

    ” And yes, the comment sections are largely entertainment.”

    Ok, I see :)

  45. 95

    EGS 84: It led to chaos in the electrical grid that forced Germany to import dirtier electricity (and nuclear elec. power) from neighbors and to expand lignite mining and lignite-fired electrical power, something that actually increased its carbon footprint and led to missing its “climate targets.”

    BPL: Your information is obsolete. German CO2 emissions were down last year.

  46. 96

    EGS 83: . I’m genuinely worried about anthropogenic global warming but fear that we’ve lost sight of the main current drivers of this problem from the IPCC’s undue obsession with one greenhouse molecule

    BPL: I gave you a broad hint as to why when I asked you if you knew about analysis of variance. Apparently you don’t, so I’ll give you the information you missed. CO2 accounts for 85% of the variance of temperature for the last 170 years–ALL of the last 170 years, taken as a whole, and you have to take it as a whole for a proper analysis, not isolate bits of it like you’re doing.

    That means that all other sources of variation in that period, including other greenhouse gases, solar variations, volcanism, artificial aerosols, climate cycles such as the PDO and ENSO, etc., etc., etc., can only account for 15% during that period. That’s why climate scientists are “obsessed” with CO2–because it’s the biggest and most obvious problem.

  47. 97
    EGS says:

    MA Rodger@90

    “And the prime candidates you choose to replace CO2 – well they are the second and third biggest contributors to AGW but if anybody sensible examined the atmospheric levels of N2O (plotted out here) and CH4 (plotted out here), there is no great increase to be seen that could possibly provide a reason for the post-1970 global warming.”

    Did you even look at your graphs?

    No exponential rise in global atmospheric N20 concentrations since 1965? No exponential rise in global atmospheric CH4 concentrations between 1915 and 2000? Both lines are nearly vertical!

    Your third graph is misleading, only showing the 5 year rolling averages of annual changes in various GHG forcing. What matters is the cumulative radiative forcing of these gasses. What is the estimated cumulative radiative forcing of N2O, CH4 and halocarbons since 1950? And what is it relative to CO2?

    Perhaps others might have or know where to find that data. Thank you.

  48. 98
    Ignorant Guy says:

    EGS,
    If you want to know the answers to these questions:
    “So, how much did the warming influence from GHGs increase last year?
    How does that compare with previous years?
    What gases contribute most to the change each year?”
    Check out these pages:
    https://www.esrl.noaa.gov/gmd/aggi/
    https://www.esrl.noaa.gov/gmd/aggi/aggi.html
    This is short and easy reading and a good place to start.

  49. 99

    #88, DBB–

    Thanks for linking that provocative finding. It’s a surprising but logical counterpoint to the familiar “CO2 is plant food” meme.

    Presumably, this could be an important mechanism underlying the so-called ‘insect apocalypse’ that may be underway globally.

  50. 100

    #93, EGS–

    And what EVIDENCE is there that cooling anthropogenic aerosols suddenly cleared out of the atmosphere in the late 1970s and 1980s?

    Well, “cleared out” is certainly a rhetorical flourish, but:

    A new annual estimate of anthropogenic global and regional sulfur dioxide emissions has been constructed spanning the period 1850–2005 using a bottom-up mass balance method, calibrated to country-level inventory data. Global emissions peaked in the early 1970s and decreased until 2000…

    https://www.atmos-chem-phys.net/11/1101/2011/