New Study: Modelers Got Aerosols All Wrong…CO2 Climate Sensitivity Likely Another 0.4°C Overstated!

Die kalte Sonne reports on a new aerosol study by Liu et al.

The results are a major blow to the high greenhouse-gas climate sensitivity modelers.

IPCC scientists have a favorite wild card they often use to explain serious model discrepancies: aerosols. Mysterious cooling events in the past are often explained away by aerosols from major volcanic eruptions, for example. They act to filter out sunlight.

According to IPCC climate models, the mean global temperature should have risen by 1.5°C since 1850 due to the higher CO2 concentrations. But best estimates show that it has instead risen by only 1.1°C. So what about the missing 0.4°C?

Naturally, the missing 0.4°C of warming since 1850 gets explained by the higher 20th century aerosol levels in the atmosphere – due to the burning of fossil fuels. Air pollution by man over the course of the late 19th century and entire 20th century are said to have dimmed the earth, and thus this explains the 0.4°C less warming.

Surprise: global aerosol emissions have been flat over past 250 years

But now results by a new study appearing in the journal Science Advances by Liu et al tells us that the forcing by aerosols had to have been overestimated by climate modelers. IPCC modelers insisted that 20th century aerosol concentrations were higher than during the pre-industrial times, and this is what kept the climate from warming by 1.5°C.

According to the scientists led by Liu, however, atmospheric aerosols in the preindustrial times were just as high as they were just recently. They were in fact more or less constant over the past 250 years. No change means it could not have been aerosols putting the brakes on temperature rise:

Image: Science Advances, Liu et al

That’s a real embarrassment for the IPCC modelers. It means CO2 climate sensitivity has been overestimated.

Aerosol concentrations have changed very little

The above chart is the result they found from records of 14 Antarctic ice cores and 1 central Andean ice core. These tell us that “historical fire activity in the Southern Hemisphere (SH) exceeded present-day levels”. Forest fires back then were much worse, and so more aerosol emissions were greater than modelers believe!

“The results come as a real surprise,” reports Die kalte Sonne.

Significance: CO2 climate sensitivity overstated in models

The researchers found that instead of aerosols increasing during the 20th century, they likely in fact decreased by 30% over the 20th century! This means that aerosols could not have suppressed the warming by 0.4°C, meaning the climate sensitivity by manmade greenhouse gases has to be dialed back accordingly.

The models have got the aerosols all wrong.

Confirmed by previous study

The new findings are underpinned by earlier findings in a 2018 study by Hamilton et al, who also found “significantly increased aerosol concentrations in the pre-industrial atmosphere.”

“Stark contradiction” to model assumptions

“The high natural aerosol emissions of the preindustrial time are thus clearly a global phenomenon,” reports Die kalte Sonne. “The documented constancy of the aerosol total emissions are in stark contradiction to the assumptions in the IPCC climate models.”

CO2 warming effect has to be much less

“The consequences for the climate models could be enormous,” Die kalte Sonne adds. This means that CO2’s warming effect thus has to be much less. “The study tells us that the CO2 climate sensitivity indeed has to be in the lower range of the IPCC’s 1.5-4.5°C warming for a doubling of CO2.”

12 responses to “New Study: Modelers Got Aerosols All Wrong…CO2 Climate Sensitivity Likely Another 0.4°C Overstated!”

  1. Richard Greene

    Yet another TCS guess, even worse than the previous 1,264 guesses !

    First of all the right answer is we don’t know.
    But if one assumes all warming in the past 120 years was caused by CO2,
    with no evidence that’s true, then a worst case view CO2 = it’s not a powerful greenhouse gas. The real TCS is still “no one knows”

    The study reported here is worthless !

    NO ONE knows the actual global average temperature iwith n 1850, 1880 or even 1920. There were far too few land weather stations, very few in the Southern Hemisphere, and ocean measurements were even worse. The claimed numbers could easily be off by more than 0.4 degree C, in either direction.

    Aerosols from volcanoes temporarily block some sunlight.
    Okay, that makes sense.
    But the biggest (and wrong) claim for aerosols was that they more than offset the warming effect of CO2 from 1940 to 1975, so we had global cooling. When a new global warming trend began in 1975, the Climate Liars would have us believe the (air pollution) aerosols suddenly fell out of the sky in 1975.

    We Climate Skeptics knew that was baloney. So the Climate Liars responded by gradually eliminating the -0.5 degrees C, of global cooling from 1940 to 1975 ( US NCAR data ) … and now US NASA-GISS claims there was never any global cooling in that period !

    That’s science fraud, and the Climate Liars are experts on science fraud.

    1. Chris Hanley

      According to HADCRUT4 the Southern Hemisphere experience a drop in temperature 1940 – 1960 although that has been incrementally adjusted away.
      My understand is that there is little air circulation across the Equator due to the Coriolis effect.
      There was and is little industrial air pollution in the Southern Hemisphere — apart from the fact that air pollution anywhere is relatively local in any case.
      ‘It would be good to remove at least part of the 1940s blip, but we are still left with “why the blip” ‘ (Climategate email: Tom Wigley to Phil Jones 27 Sep 2009).
      The temperature drop in the SH 1940 – 1960 remains unexplained despite apparently desperate efforts to ‘disappear’ it

  2. Tom Anderson

    During the less great Global Cooling Scare of the 1970s, researchers at NASA’s GISS meteorological facility studied whether CO2 emissions could stave off what was then agreed to be the coming ice age. The scientists, S.I. Rasool and Stephen W. Schneider (yes, the Global Warming Stephen Schneider), concluded that the aerosols from burning fossil fuel not only offset what warming CO2 might provide but would continue to rise at a constant and block solar energy while CO2’s effectiveness (if any) declined in an inverse logarithmic manner, the Richter Scale in reverse. (See, Rasool, S.J., and Stephen W. Schneider, “Atmospheric carbon dioxide and aerosols: Effects of large increases on global climate,” Science, v. 173,July 1971, pp. 138-141.) R & S also dismissed the possibility of runaway warming.

    Odd how everybody forgets these things. The aerosol-gas relationship still applies, and burning fossil fuels seem necessarily to cool more robustly than they (theoretically) warm.

    I propose we start chanting, “Keep cool with fossil fuel.”

  3. Tom Anderson

    Editor’s comment: “… rise at a constant RATE.” Sorry.

  4. Ulric Lyons

    The UK had record high daytime maximum temperatures during very high levels of industrial air pollution, in 22-27 Feb 2019, and in Easter 2011.
    The Moscow heatwave of 2010 was exacerbated by forest fire smoke.
    The UK summer heat of 1783 was exacerbated by volcanic fumes and dust from the Laki eruption.

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  6. RoHa

    “Modelers Got Aerosols All Wrong…”
    ” Climate Model Error Overestimates CO2 Impact On Global Temps By Factor Of 5″

    Anyone would think you are suggesting that we are not doomed.

  7. bonbon

    The comment in video of the models running with one foot on the CO2 throttle, and the other on the Aerosol brake is hilarious.
    But that is what the models are doing!

    I wonder how a Tesla would react to that kind of driving?

  8. drumphish

    In my neck of world, on November 16, 1939, the high temp for that day set a record at 65 F. On November 16, 1940, a record low temp was set a minus 22 degrees F.

    November of 1939 had an Indian Summer, same date the next year was winter weather conditions. Winter weather like that is always a war of all against all.

    There isn’t a meteorological/climate model that can predict weather like that.

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