Warming to it (globally)
The almost linear increase in global mean temperature since 1979 has been mapped out by Grant Foster of Tempo Analytica in the US and Stefan Rahmstorf from the Potsdam institute for Climate Impact Research, thanks to the satellite microwave-sensor imagery, available since that date.
Comparing surface based records with the microwave sensors improved reliability as the lower troposphere and near surface temperatures are strongly related. Nevertheless, useful insights were possible from such a comparison. The three main causes of of short-term temperature variation are known to be:
the El Nino or ENSO oscillation;
volcanic eruptions; and
solar cycles and similar solar variation.
Less noisy data were achieved by largely removing these influences as independent measures of each can be obtained. This led to meaningful results concerning their influence on mean temperatures, instead of simply recording their short-term effect.
Five of the best-known global temperature measures, from the US and the UK, were analysed by Grant and Stefan.
Figure 1. Five major global temperature records.
All five data sets give warming rates which are consistent with one another. The largest difference is between the GISS and UAH data, but the difference fails statistical significance testing. Even so, the two lowest rates are for LT temperature while the three highest are for surface temperature. This suggests the possibility that the LT is warming more slowly than the surface, although we reiterate that such a suggestion is not supported with statistical significance; Credit: Tempo Analytica/Potsdam institute for Climate Impact Research
Using regression analysis, the adjusted data looked like this! The correlations from such widely gathered results show a great amount of agreement.
Annual averages of the adjusted data; Credit: Tempo Analytica/Potsdam institute for Climate Impact Research
Looking for changes in the rate over time, there were none to alter the "monotonous increase" in temperatures.
Influences of ENSO, volcanoes and solar variations showed the following results:
Influence of exogenous factors on global temperature for GISS (blue) and RSS data (red). (a) MEI; (b) AOD; (c) TSI; Credit: Tempo Analytica/Potsdam institute for Climate Impact Research
Enso (El Nino) turns out to be more of an influence than volcanic effects and both are more effective than the influence of solar variation. MEI is the multivariate el Nino index, AOD is the aerosol optical depth (volcanic dust measurement) and TSI is the total solar irradiance.
From such a comprehensive data set, we can conclude that known factors influence in the short term, while lower troposphere temperatures are influenced by them to a much greater extent than surface temperatures. We can observe now a Global Warming Signal, by isolating these effects, due predominantly to factors which are not measured here. There are only a very few possibilities. No organism is able to influence climate as much as human industry (in the widest sense). These 32 years have witnessed a remarkably steady rate of warming, with only natural causes deviating briefly from that (anthropogenically created) rate. Like a signal from "inner space", the authors have given us this true global warming data set:
Credit: Tempo Analytica/Potsdam institute for Climate Impact Research
Like it or not, we seem to be the only possible cause of the malaise. The next few decades can only see furtherance of the steady increase in degrees and decline in our global stability. Think sea levels, ice loss and species decline. If you want a positive, be relieved that at least there is no acceleration in global warming. Yet!
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