Re: [asa] High School Genius & Her Science Project

From: PvM <>
Date: Tue May 29 2007 - 22:07:56 EDT

More problems
<quote>Second, they do not include solar activity, which is at an
11,000 year high. The graph below (Solanki 2006) shows solar activity
for the past 12,000 years. In this graph you can see that there was an
increase in solar activity during the same warming periods listed

See Unusual activity of the Sun during recent decades compared to the
previous 11,000 years, Nature, Vol. 431, No. 7012, pp. 1084 - 1087, 28
October 2004.

The page also quotes
<quote>Although the rarity of the current episode of high average
sunspot numbers may indicate that the Sun has contributed to the
unusual climate change during the twentieth century, we point out that
solar variability is unlikely to have been the dominant cause of the
strong warming during the past three decades.</quote>

However compare this with

<quote> This comparison shows without requiring any recourse to
modeling that since roughly 1970 the solar influence on climate
(through the channels considered here) cannot have been dominant.
In particular, the Sun cannot have contributed more than 30% to the
steep temperature increase that has taken place since then,
irrespective of which of the three considered channels is the dominant
one determining Sun-climate interactions: tropospheric heating caused
by changes in total solar irradiance, stratospheric chemistry
influenced by changes in the solar UV spectrum, or cloud coverage
affected by the cosmic ray flux. </quote>

S. K. Solanki and N. A. Krivova , Can solar variability explain global
warming since 1970? JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. A5,
1200, doi:10.1029/2002JA009753, 2003

And finally

P. Foukal , C. Fröhlich , H. Spruit T. M. L. Wigley
Variations in solar luminosity and their effect on the Earth's climate

Variations in the Sun's total energy output (luminosity) are caused by
changing dark (sunspot) and bright structures on the solar disk during
the 11-year sunspot cycle. The variations measured from spacecraft
since 1978 are too small to have contributed appreciably to
accelerated global warming over the past 30 years. In this Review, we
show that detailed analysis of these small output variations has
greatly advanced our understanding of solar luminosity change, and
new understanding indicates that brightening of the Sun is unlikely to
have had a significant influence on global warming since the
seventeenth century. Additional climate forcing by changes in the
Sun's output of ultraviolet light, and of magnetized plasmas, cannot
be ruled out. The suggested mechanisms are, however, too complex to
evaluate meaningfully at present.

You get the picture?

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Received on Tue May 29 22:09:10 2007

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