Tuesday, January 22, 2013

Don't worry, be happy: Warmist Revkin reads a NASA article on solar variability and climate that uses words like "significant", "important", "whopping", "persuasive", and "overpowering", then concludes "No signs of signif sun role in warming"

Twitter / Revkin: Neat @NASA update on sun role ...
Neat update on sun role in Earth's climate. No signs of signif sun role in warming; but Maunder Min. signs, yes.
Twitter / ClimateOfGavin: @Revkin @nasa Andy, note that ...
@Revkin @nasa Andy, note that our ability to forecast solar activity is very low, even for a single cycle ahead.
Solar Variability and Terrestrial Climate - NASA Science
There is, however, a dawning realization among researchers that even these apparently tiny variations can have a significant effect on terrestrial climate.
One of the participants, Greg Kopp of the Laboratory for Atmospheric and Space Physics at the University of Colorado, pointed out that while the variations in luminosity over the 11-year solar cycle amount to only a tenth of a percent of the sun's total output, such a small fraction is still important. "Even typical short term variations of 0.1% in incident irradiance exceed all other energy sources (such as natural radioactivity in Earth's core) combined," he says.

Of particular importance is the sun's extreme ultraviolet (EUV) radiation, which peaks during the years around solar maximum.  Within the relatively narrow band of EUV wavelengths, the sun’s output varies not by a minuscule 0.1%, but by whopping factors of 10 or more.  This can strongly affect the chemistry and thermal structure of the upper atmosphere.
Indeed, Gerald Meehl of the National Center for Atmospheric Research (NCAR) presented persuasive evidence that solar variability is leaving an imprint on climate, especially in the Pacific. According to the report, when researchers look at sea surface temperature data during sunspot peak years, the tropical Pacific shows a pronounced La Nina-like pattern, with a cooling of almost 1o C in the equatorial eastern Pacific. In addition, "there are signs of enhanced precipitation in the Pacific ITCZ (Inter-Tropical Convergence Zone ) and SPCZ (South Pacific Convergence Zone) as well as above-normal sea-level pressure in the mid-latitude North and South Pacific," correlated with peaks in the sunspot cycle.

The solar cycle signals are so strong in the Pacific, that Meehl and colleagues have begun to wonder if something in the Pacific climate system is acting to amplify them.
Dan Lubin of the Scripps Institution of Oceanography pointed out the value of looking at sun-like stars elsewhere in the Milky Way to determine the frequency of similar grand minima. “Early estimates of grand minimum frequency in solar-type stars ranged from 10% to 30%, implying the sun’s influence could be overpowering. More recent studies using data from Hipparcos (a European Space Agency astrometry satellite) and properly accounting for the metallicity of the stars, place the estimate in the range of less than 3%.” This is not a large number, but it is significant.

Indeed, the sun could be on the threshold of a mini-Maunder event right now. Ongoing Solar Cycle 24 is the weakest in more than 50 years.
“If the sun really is entering an unfamiliar phase of the solar cycle, then we must redouble our efforts to understand the sun-climate link,” notes Lika Guhathakurta of NASA’s Living with a Star Program, which helped fund the NRC study. “The report offers some good ideas for how to get started.”

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