Saturday, February 9, 2013

Oops: Sunspot Count Lower than Projected - Unexpectedly!

If you've been tracking the debate on the sun's influence on climate, then you know that (somewhat counter-intuitively) the sun's luminosity (energy output) increases when there are more sunspots (see here for an explanation).  For years, climate scientists left solar luminosity variation out of their models, and denied that it had any significant effect on weather or climate.  Skeptics of anthropogenic global warming (AGW) have long been pointing to the high sunspot counts (and therefore high solar luminosity) of the last solar cycle as a likely cause of the global warming observed in the '90s and early '00s.  Over the past couple of years, even the mainstream climate scientists are changing their position on this, as more and more observational evidence comes in that the skeptics were right.

Meanwhile, over at NOAA they've been trying to predict what the current solar cycle's sunspot count will be, and they keep getting surprised – by how low the count is  (see chart below, sourced here).  At the same time, all observational evidence of continued global warming has come to a halt – temperatures have been flat for over five years now.  AGW skeptics point to this as evidence that the solar luminosity is causing global warming, but really all they have so far is a good correlation; causation has yet to be established.  But...some mainstream climate scientists are now pursuing observations aimed to establishing that causation (see, for example, the recent observations showing that solar luminosity variation in the ultraviolet spectrum is far higher than it is in optical – and the energy output of the sun is much higher in that spectral region than it is in the optical region).

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