Manmade greenhouse warming to date offset by ‘uncertain amount’ of manmade cooling, says National Academy of Sciences

From the new National Academy of Sciences report on climate modeling:

Current climate models are calibrated during their development process to match observations within reasonable uncertainty ranges. However, the warming to date due to greenhouse gas increases has been partially compensated by an uncertain amount of cooling caused by
human-induced enhancement of light scattering by aerosols and by their effect on clouds; this compensation has been estimated to be from 20 to 70 percent (with 90 percent confidence) based on a range of observational and model-based studies (IPCC, 2007d). Over the 21st century, global aerosol emissions are expected to not increase further, but greenhouse gas emissions are likely to accelerate for at least the next few decades, so this compensation will become less significant. Because of the uncertain cooling by aerosols the current warming cannot be used to constrain the “climate sensitivity.” Thus, the simulated 21st-century global-average warming varies across the international suite of climate models with a range of approximately 30 percent as is further discussed in Chapter 4.

Read the report.

9 thoughts on “Manmade greenhouse warming to date offset by ‘uncertain amount’ of manmade cooling, says National Academy of Sciences”

  1. Anything in the report about the Very Quiet Sun spot cycle #24 and the decline in last two sunspot cycles? The sun is the main climate driver on earth and if the do not mention it in the report they are not disclosing everything and what I feel is main reason for cooling. Happened in the past and history is repeating.
    Many pages in report to read.

  2. Only one problem: Sagan’s aerosol optical physics which is behind the ‘dark clouds contain small droplets’ claim is wrong.

    In reality the sign of the effect is reversed as can be seen by simple observation.

    This means the real AGW has been restriction of droplet coarsening.

    Real CO2 CS <0.1 K.

  3. When your theory gets repeatedly falsified, you normally change the theory to fit the observations. These “scientists” don’t change the basic theory, they tinker around the edges with aerosols. Even after listing numerous problems with the climate models, they still believe and cling to the models. Ain’t science grand?

  4. And it is always the aerosols. That is what they use as an excuse for the lack of CO2 pumping. The Alarmists at this point are predicting so many aerosols that we should be choking to death on them.

  5. Yes, of course; after all, man controls the earth’s climate. The sun has nothing to do with the earth’s climate.

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