Friday, January 04, 2013

No correlation between global temperatures and CO2

For a good start to the New Year how about taking a look at a recent paper published in the journal Earth System Dynamics? Entitled 'Polynomial cointegration tests of anthropogenic impact on global warming' the paper, which is published as open access and can be downloaded for free, the paper uses robust statistical methods to test for spurious correlations between global temperature and the main drivers of the greenhouse effect (eg CO2, aerosols, total solar irradiance).

To quote from the abstract:
We show that although these anthropogenic forcings share a common stochastic trend, this trend is empirically independent of the stochastic trend in temperature and solar irradiance. Therefore, greenhouse gas forcing, aerosols, solar irradiance and global temperature are not polynomially cointegrated. This implies that recent global warming is not statistically significantly related to anthropogenic forcing. On the other hand, we find that greenhouse gas forcing might have had a temporary effect on global temperature.
Or from the paper itself:
We have shown that anthropogenic forcings do not polynomially cointegrate with global temperature and solar irradiance. Therefore, data for 1880–2007 do not support the anthropogenic interpretation of global warming during this period.
Given the complexity of Earth’s climate, and our incomplete understanding of it, it is difficult to attribute to carbon emissions and other anthropogenic phenomena the main cause for global warming in the 20th century.
Also worth reading are the reviewers comments, which are very positive, a point to keep in mind when the paper is attacked by the climate faithful. And, as always in these situations, we can only speculate on the orgy of publicity (not least from the BBC) the paper would have generated had the results shown a true correlation between CO2 and global temperatures...

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