Abstract. In this paper we will prove that GCM-models used in IPCC reportAR5 fail to calculate the influences of the low cloud cover changes on the globaltemperature. That is why those models give a very small natural temperaturechange leaving a very large change for the contribution of the green housegases in the observed temperature. This is the reason why IPCC has to use avery large sensitivity to compensate a too small natural component. Furtherthey have to leave out the strong negative feedback due to the clouds in orderto magnify the sensitivity. In addition, this paper proves that the changes inthe low cloud cover fraction practically control the global temperature.
The climate sensitivity has an extremely large uncertainty in the scientific lit-erature. The smallest values estimated are very close to zero while the highestones are even 9 degrees Celsius for a doubling of CO2. The majority of the papersare using theoretical general circulation models (GCM) for the estimation. Thesemodels give very big sensitivities with a very large uncertainty range. Typicallysensitivity values are between 2–5 degrees. IPCC uses these papers to estimatethe global temperature anomalies and the climate sensitivity. However, there area lot of papers, where sensitivities lower than one degree are estimated withoutusing GCM. The basic problem is still a missing experimental evidence of the cli-mate sensitivity. One of the authors (JK) worked as an expert reviewer of IPCCAR5 report. One of his comments concerned the missing experimental evidence forthe very large sensitivity presented in the report . As a response to the com-ment IPCC claims that an observational evidence exists for example in TechnicalSummary of the report. In this paper we will study the case carefully.
2. Low cloud cover controls practically the global temperature
The basic task is to divide the observed global temperature anomaly into twoparts: the natural component and the part due to the green house gases. In orderto study the response we have to re-present Figure TS.12 from Technical Summaryof IPCC AR5 report (1). This figure is Figure 1. Here we highlight the subfigure“Land and ocean surface” in Figure 1. Only the black curve is an observed tem-perature anomaly in that figure. The red and blue envelopes are computed usingclimate models. We do not consider computational results as experimental evi-dence. Especially the results obtained by climate models are questionable becausethe results are conflicting with each other.
Figure 1.Figure TS.12 on page 74 of the Technical Summary ofthe IPCC Fifth Assessment report (AR5).
In Figure 2 we see the observed global temperature anomaly (red) and globallow cloud cover changes (blue). These experimental observations indicate that1 % increase of the low cloud cover fraction decreases the temperature by 0.11°C.This number is in very good agreement with the theory given in the papers [3,2, 4]. Using this result we are able to present the natural temperature anomalyby multiplying the changes of the low cloud cover by−0.11°C/%. This naturalcontribution (blue) is shown in Figure 3 superimposed on the observed temperatureanomaly (red). As we can see there is no room for the contribution of greenhousegases i.e. anthropogenic forcing within this experimental accuracy. Even thoughthe monthly temperature anomaly is very noisy it is easy to notice a couple ofdecreasing periods in the increasing trend of the temperature. This behavior cannotbe explained by the monotonically increasing concentration of CO2and it seems tobe far beyond the accuracy of the climate models.
Figure 2. Global temperature anomaly (red) and the globallow cloud cover changes (blue) according to the observations. Theanomalies are between summer 1983 and summer 2008. The timeresolution of the data is one month, but the seasonal signal isremoved. Zero corresponds about 15°C for the temperature and26 % for the low cloud cover.
The red curve in Figures 2 and 3 corresponds to the black curve, between years1983 and 2008, in the above-mentioned subfigure “Land and ocean surface”. If theclouds and CO2were taken into account correctly in the climate models both theblue and red envelopes should overlap the observed black curve. As we see the trendof the blue envelope is more like decreasing. We suggest this is due to a wrong ormissing processing of the low cloud cover contribution. In the report AR5 it is evenrecognized that the low clouds give the largest uncertainty in computation. In spiteof this IPCC still assumes that the difference between the blue and red envelopesin Figure 1 is the contribution of greenhouse gases.Unfortunately, the time interval (1983–2008) in Fig 2 is limited to 25 yearsbecause of the lack of the low cloud cover data. During this time period the CO2concentration increased from 343 ppm to 386 ppm and both Figures 1 (IPCC)and 2 show the observed temperature increase of about 0.4°C. The actual globaltemperature change, when the concentration of CO2raises fromC0toC, is∆T=∆T2CO2lnC/C0ln 2−11°C·∆c,(1)where ∆T2CO2is the global temperature change, when the CO2concentration isdoubled and ∆cis the change of the low cloud cover fraction. The first and secondterm are the contributions of CO2 and the low clouds, respectively.
Figure 3. Global natural temperature anomaly (blue) super-imposed on the observed (red) temperature anomaly. The blueanomaly is derived using the observed low cloud cover data fromFigure 2. There are half a dozen very sharp ghost spikes in theobserved (red) temperature anomaly. The Pinatubo eruption andthe strong El Ni ̃no are clearly seen.
Using the sensitivity ∆T2CO2= 0.24°C derived in the papers [3, 2, 4] the contributionof greenhouse gases to the temperature is only about 0.04°C according to the firstterm in the above equation. This is the reason why we do not see this small increasein temperature in Figure 3, where the temperature anomaly is quite noisy with onemonth time resolution. It is clearly seen in Figure 2 that the red and blue anomaliesare like mirror images. This means that the first term is much smaller than theabsolute value of the second term (11°C·∆c) in equation (1).It turns out that the changes in the relative humidity and in the low cloudcover depend on each other . So, instead of low cloud cover we can use thechanges of the relative humidity in order to derive the natural temperature anomaly.According to the observations 1 % increase of the relative humidity decreases thetemperature by 0.15°C, and consequently the last term in the above equation canbe approximated by−15°C∆φ, where ∆φis the change of the relative humidity atthe altitude of the low clouds.Figure 4 shows the sum of the temperature changes due to the natural andCO2contributions compared with the observed temperature anomaly. The naturalcomponent has been calculated using the changes of the relative humidity. Nowwe see that the natural forcing does not explain fully the observed temperatureanomaly. So we have to add the contribution of CO2(green line), because the time interval is now 40 years (1970–2010). The concentration of CO2has now increasedfrom 326 ppm to 389 ppm. The green line has been calculated using the sensitivity0.24°C, which seems to be correct. In Fig. 4 we see clearly how well a change inthe relative humidity can model the strong temperature minimum around the year1975. This is impossible to interpret by CO2concentration.The IPCC climate sensitivity is about one order of magnitude too high, becausea strong negative feedback of the clouds is missing in climate models. If we payattention to the fact that only a small part of the increased CO2concentration isanthropogenic, we have to recognize that the anthropogenic climate change doesnot exist in practice. The major part of the extra CO2is emitted from oceans ,according to Henry‘s law. The low clouds practically control the global averagetemperature. During the last hundred years the temperature is increased about0.1°C because of CO2. The human contribution was about 0.01°C.
Figure 4. Observed global mean temperature anomaly (red),calculated anomaly (blue), which is the sum of the natural andcarbon dioxide contributions. The green line is the CO2 contribu-tion merely. The natural component is derived using the observedchanges in the relative humidity. The time resolution is one year.
3.ConclusionWe have proven that the GCM-models used in IPCC report AR5 cannot computecorrectly the natural component included in the observed global temperature. Thereason is that the models fail to derive the influences of low cloud cover fractionon the global temperature. A too small natural component results in a too largeportion for the contribution of the greenhouse gases like carbon dioxide. That is why IPCC represents the climate sensitivity more than one order of magnitude largerthan our sensitivity 0.24°C. Because the anthropogenic portion in the increasedCO2is less than 10 %, we have practically no anthropogenic climate change. Thelow clouds control mainly the global temperature.