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The Sun Drives Climate

June 5, 2013


The last abstract is the only one that addresses the evidence for what might have caused the modicum of late 20th century warming, and it is the most revealing

By coincidence, this happens to be a paper I wrote about in 2011. It is Knud Lassen’s 1999 update to his seminal 1991 paper with Friis-Christensen. Their original research had found a strong correlation between solar cycle length and global temperature change:

Solar cycle length and temp, friis-christensen-lassen

Evidence of a substantial solar effect on climate would soon come to be regarded as “contrarian” and Lassen at least seems to have been eager to get over to the safe side and renounce his earlier work.  When the 1997-98 El Nino caused global temperatures to spike dramatically Lassen was hair-trigger on the opportunity to issue a 1999 update, declaring that with the rapid increase in recent temperatures the correlation between solar cycle length and temperature had been broken.

This really was in reaction just to the El Nino spike. There is no way that Lassen could have said in 1996 that the planet had warmed too much to consist with the pattern he and Friss-Christensen had discovered through 1991. Solar cycle 22, which ended in 1996, was the shortest of the modern-maximum era so Lassen should at that point have been expecting temperatures to rise, but take a look at the satellite temperature record through 96. Unless you want to cherry pick end points there is no significant trend going back from 96 to the beginning of the record:


Before the El Nino, Lassen should have been seeing temperatures as below what his 1991 paper would predict. Only the 97-98 El Nino offered Lassen a data-based opportunity to bail on his now-contrarian earlier work and claim that temperatures had become too high, and he jumped right on it, even though the whole world knew that the temperature spike was due to an ocean oscillation and hence would be at least largely temporary.

This was a desperately unscientific move. While Lassen was still writing his update in mid ’99 temperatures had already dropped back to 1990 levels. His eight year update was outdated before it was published.

So how eager has Lassen been to update again, now that the next dozen years of data have strongly supported the solar warming theory? Crickets. The long solar cycle 23 has coincided with at least an extended pause in global warming and Mr. rush-to-update is nowhere to be found.

Bah, who needs him? Others have gone on to discover that the stronger correlation is between solar cycle length and global temperature change over the subsequent solar cycle, suggesting that the planet may now be heading into a cooling phase.

The above was from:

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