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(14) SOLAR IRRADIANCE SINCE 1750

Paul Biggs [p.m.biggs@bham.ac.uk]

Dear Benny,

Re; Andrew Glikson, INCREASE IN SOLAR IRRADIANCE SINCE 1750 ACCOUNTS FOR NO
MORE THAN ABOUT FIVE PERCENT OF GLOBAL WARMING (CCNet, 12 March 07)

Andrew Glikson neglects to mention that IPCC AR4 SPM rates the 'level of
scientific understanding' of solar irradiance as 'low.' Furthermore, only
considering irradiance ignores the potentially more important contribution of
solar eruptivity. Nir Shaviv has calculated that, of the observed 0.6±0.2°C
20th century warming,  about 0.5±0.2C can be attributed to the solar/cosmic ray
flux/climate link. Without any effect of cosmic rays, the increase in solar
luminosity would correspond to an increased temperature of about 0.16 ± 0.04C.
The solar/cosmic rays/climate link implies that climate sensitivity to a
doubling of CO2 is low - around 1C:

http://www.sciencebits.com/CO2orSolar

For an objective view of some of the errors, omissions and uncertainties in
IPCC AR4, I recommend the weblog of Roger Pielke Sr:

http://climatesci.colorado.edu/

and his new book 'Human Impacts on Weather and Climate.'

http://www.cambridge.org/catalogue/catalogue.asp?isbn=0521840864

Regards,

Paul Biggs
p.m.biggs@bham.ac.uk