Jul

17

'No Sun link' to climate change
By Richard Black
BBC Environment Correspondent

A new scientific study concludes that changes in the Sun's output cannot be causing modern-day climate change. It shows that for the last 20 years, the Sun's output has declined, yet temperatures on Earth have risen. It also shows that modern temperatures are not determined by the Sun's effect on cosmic rays, as has been claimed. 

The "greenhouse" hypothesis is that the increased CO2 levels are preventing the sun's heat from being radiated back out into space. There is no doubt that this is true. What is still in question is the magnitude of the effect and the likelihood that there are other contributing causes to the fluctuations in earth's surface temperatures.

The hypothesis about cosmic rays is a theory about another contributing cause. The difficulty with both the hypothesis about cosmic rays and its rebuttal is that neither side has a time series of data with sufficient length to be a reasonable basis for any robust conclusions.

In the last 20 years the data show that there has been a negative correlation between the sun's energy output and the earth's surface temperatures. But (the economist's other hand) the data from the period leading up to 1980 show a strong positive correlation. So, the debate has hardly been settled either way. Saying "we still don't know" is probably the bravest of all positions to take on these matters; you can be guaranteed to have arrows in your back and your chest. 

Craig Mee notices:

Read the sunspots.

The mud at the bottom of B.C. fjords reveals that solar output drives climate change — and that we should prepare now for dangerous global cooling 


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