The hypothesised cloud feedback – alone – is of comparable size to the current global warming!

Have you ever wondered how strong the cloud feedback effect is – as compared to the net energy accumulation on earth?

It is quite amazing, but it turns out that the hypothesised total cloud feedback effect is about equal to the current global energy accumulation, equal to the current global warming.

First – the net surface warming:

In my post: IPCC got all bets covered! I show how the net warming effect can be deduced from the UN IPCC; AR5;. I deduced a value of 0.6 W/m² from the IPCC report (The value is provided in the table). The value I deduce from the IPCC report is corroborated by the following article in Wikipedia:

Wikipedia: Earth’s energy budget

Earth’s energy imbalance
If the incoming energy flux is not equal to the outgoing thermal radiation, the result is an energy imbalance, resulting in net heat added to or lost by the planet (if the incoming flux is larger or smaller than the outgoing). Earth’s energy imbalance measurements provided by Argo floats detected accumulation of ocean heat content (OHC). The estimated imbalance was measured during a deep solar minimum of 2005-2010 at 0.58 ± 0.15 W/m².[11] Later research estimated the surface energy imbalance to be 0.60 ± 0.17 W/m².[12] ”

Second – the cloud feedback effect

The cloud feedback effect is quantified by IPCC and presented in UN IPCC; WGI; AR5 report; figure 7.10 in  Chapter 7 – Clouds and aerosols Page 588.


Figure 7.10 | Cloud feedback parameters as predicted by GCMs for responses to CO2 increase including rapid adjustments. Total feedback shown at left, with centre light- shaded section showing components attributable to clouds in specific height ranges (see Section, and right dark-shaded panel those attributable to specific cloud property changes where available. The net feedback parameters are broken down in their longwave (LW) and shortwave (SW) components. Type attribution reported for CMIP3 does not conform exactly to the definition used in the Cloud Feedback Model Intercomparison Project (CFMIP) but is shown for comparison, with their ‘mixed’ category assigned to middle cloud.

As can be seen in this figure the unit for cloud feedback is W/m²°C .
°C in this expression is the increase in surface temperature since preindustrial times. IPCC provides the following value for the temperature increase since preindustrial times:

The globally averaged combined land and ocean surface temperature data as calculated by a linear trend, show a warming of 0.85 [0.65 to 1.06] °C3, over the period 1880 to 2012

Page 5

Hence – we can calculate the total cloud feedback effect by multiplying the central estimate for total cloud feedback effect from CMIP5 read from figure 7.10: 0.65 W/m²°C by 0.85 °C The result is 0.6 W/m².

Hence the total cloud feedback effect deduced from figures in the IPCC report is currently: 0.6 W/m².


It was a great surprise to me that the net energy accumulation 0.6 W/m²  is more or less exactly equal to the hypothesised total feedback effect from clouds: 0.6 W/m².

This seems to make the statement from Roy Spencer in his book “The great warming blunder” highly relevant:

“The insistence of the IPCC and the scientific “consensus” that clouds cannot cause climate variations continues to astound me. All atmospheric scientists know that clouds are controlled by a multitude of factors; my position is that causation between clouds and temperature flows in both directions. In contrast, the IPCC´s position is that clouds can only change in response to temperature change (temperature cause clouds). But neglecting causation in the opposite direction (clouds cause temperature) can lead to large errors in our understanding of how and why the climate system changes, as well as in our diagnosis of how sensitive the climate system is to human influences.”

The way IPCC highlight radiative forcing and fail to mention the net energy accumulation is remarkable:

In the report – IPCC highlights the net anthropological radiative forcing:
“The total anthropogenic Radiative Forcing for 2011 relative to 1750 is
2.29 [1.13 to 3.33] W m−2 …”
(WGI; AR5 – Page 13)

What IPCC does not mention with a word in the summary is that:

There is “an increase in outgoing radiation inferred from changes in the global mean surface temperature”
(WGI; AR5 – Figure TFE.4, Figure 1 The Earth’s energy budget from 1970 through 2011.)

And IPCC does not mention with a word that a central estimate for the current energy accumulation is 0.6 W/m².
(Wikipedia: Earth’s energy budget Earths energy imbalance)

And IPCC does not mention with a word that the central estimate for current total feedback from clouds is also 0.6 W/m².
(WGI; AR5 – Figure 7.10 | Cloud feedback parameters)


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