Warming Trend: PDO And Solar Correlate Better Than CO2


Watts Up With That – January 25, 2008

Watts Up With That recently did an analysis and sparked a great deal of discussion on the possible causes of global warming. The analysis was done based on the paper “US Temperatures and Climate Factors since 1895” written by Mr. D’Aleo, a meteorologist, AMS Fellow, and Executive Director of ICECAP.

The paper and commentary is about the correlation between CO2 and the average temperature as well as the average temperature with solar activity. The true discussion should be about causality since that is the important issue.  However it is a logical discussion that without correlation there may not be any causality.

Mr. Gore in his famed movie “An Inconvenient Truth” made several mistakes on correlation and inferred various causality conclusions.  We must not make the same mistake. Causality and correlation are two independent and important factors. No one should confuse one with the other and make the wrong conclusion.

I have often called for more elaborate computer models to predict the future of our climate. This is one of those cases where it would be very appropriate to understand the computer model analysis of increase or decrease solar activity on the climate models. To the best of my knowledge, this is not possible with current technology that does not model solar radiance or cloud cover.

… compare the trends by running an R2 correlation on the different data sets. The result is a coefficient of determination that tells you how well the trend curves match. When the correlation is 1.0, you have a perfect match between two curves. The lower the number, the lower the trend correlation.

If CO2 is the main driver of climate change this last century, it stands to reason that the trend of surface temperatures would follow the trend of CO2, and thus the R2 correlation between the two trends would be high.


Clearly the US annual temperatures over the last century have correlated far better with cycles in the sun and oceans than carbon dioxide. The correlation with carbon dioxide seems to have vanished or even reversed in the last decade.

You can read the article here which does an excellent job of analyzing this paper and theory. The comments are also quite revealing and should be read.

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