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CO2 and clouds: their relative roles as agents of climate change

25 Oct 2023 | Science Notes

From the CO2Science Archive: Using the most up-to-date cloud amount data from the International Satellite Cloud Climatology Project, and following the protocols of Palle et al. (2004), the authors derived globally-averaged albedo anomalies and related solar radiative forcing anomalies that were supposedly experienced by the earth over the past two decades. In addition, they explored the impacts of observed changes in the amounts of low clouds and high plus mid-level clouds that occurred between 2000 and 2004 on total radiative forcing (solar plus thermal).

Paper reviewed: Palle, E., Goode, P.R., Montanes-Rodriguez, P. and Koonin, S.E. 2006. Can earth’s albedo and surface temperatures increase together? EOS, Transactions, American Geophysical Union 87: 37,43.

Between 1985 and 2000, Palle et al. calculated that the flux of solar radiation absorbed by the earth-atmosphere system rose by about 8 Wm-2 in response to an observed decline in total cloud amount. Thereafter, however, total cloud amount began to rise; but because of a concomitant redistribution of cloud types (an increase in high and mid-level clouds that tend to warm the planet, and a decrease in low level clouds that tend to cool the planet), they concluded that the positive radiative forcing trend experienced between 1985 and 2000 may have continued to the present, even in the face of an increasing total cloud amount. If it did, and if it continued at the rate established between 1985 and 2000, we estimate it could have added another 3 Wm-2 to the total increase in radiative forcing experienced between 1985 and 2000. Last of all, the researchers note that the increase in radiative forcing produced by the concentration increases experienced by all greenhouse gases since 1850 was something on the order of only 2.5 Wm-2.

What it means
Compared to the increase in radiative forcing that may have been experienced between 1985 and 2005 as a result of observed changes in total cloud amount and the fractions of clouds located at different elevations (~11 Wm-2, according to the data and analyses of Palle et al.), the concomitant 20-year change in radiative forcing due to CO2 alone would have had to have been truly miniscule, which suggests that all of the angst manifest by climate alarmists over anthropogenic CO2 emissions is wholly misplaced. Also, if a radiative forcing on the order of 11 Wm-2 only raised mean global air temperature by a fraction of a degree, as occurred between 1985 and 2005, it would appear that earth’s climate is much less responsive to changes in radiative forcing than the world’s climate alarmists and most climate modelers claim it to be.

Palle, E., Goode, P.R., Montanes-Rodriguez, P. and Koonin, S.E. 2004. Changes in earth’s reflectance over the past two decades. Science 304: 1299-1301.

One comment on “CO2 and clouds: their relative roles as agents of climate change”

  1. There is monthly variation in average global temperature according to UAH, RSS, Hadley, and so on,
    The only thing that changes fast enough to result in those monthly changes is cloud cover and evaporation. Increased average temp…increases low level clouds….increases the albedo of the planet….increases rainfall and evaporation….and so so….
    This controls the Earth’s temperature to 288 Kelvin +/-5% on during an entire daily revolution of the planet, daylight to darkness, and essentially zero change over a whole year long orbit of the Sun. Very miraculous.
    Our schools should teach this.

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