"Roger Coppock" <rcoppock@[EMAIL PROTECTED]
> wrote in message
news:cb3bda75-e41e-491f-9794-17002c2e03eb@[EMAIL PROTECTED]
> The Sunspot Scapegoat
> Actual sunspot
> count data barely show any correlation with the observed
> global land and sea surface temperature from 1880 to
> today.
The Sun Drives Climate
Lockwood And Fröhlich Are Wrong
Nir Shaviv
http://motls.blogspot.com/2007/07/nir-shaviv-why-is-lockwood-and-frohlich.html
L & F state that from 1985, there is a discrepancy between solar
activity, which decreased, and the global temperature, which increased.
Hence, solar activity cannot explain the observed warming. This
conclusion, however, is flawed for several reasons.
Figure 1: Cosmic ray flux as a function of time. Note the minimum near
1992 that probably caused less cloudiness and warming in the 1990s
To begin with, L & W write that solar activity decreased after 1985.
This may almost be correct for the sunspot number (which remained the
same) and perhaps correct for other solar activity proxies, but this is
not correct for the cosmic rays. As is apparent from the first two
figures above and below, the 1990 solar maximum caused a larger decrease
in the cosmic ray flux, which implies that the temperature should have
been higher in the 1990's than in the 1980's. This leaves a discrepancy
between the solar maximum of 2001 which was weaker than the solar
maximum of 1990, and the observed temperature increase.
Figure 2: This inverse correlation between a smoothed international
sunspot number (green) and three graphs (thin lines) depicting cosmic
ray flux seems obviously valid.
So why has the temperature continued increasing even though the solar
activity diminished? This has to do with the second point, which is very
im****tant, but totally ignored by L & F.
L & F assume (like many others before) that there should be a one-to-one
correspondence between the temperature variations and solar activity.
However, there are two im****tant effects that should be considered and
that arise because of the climate's heat capacity (predominantly the
oceans). First, the response to short term variations in the radiative
forcings are damped. This explains why the temperature variations in
sync with the 11-year solar cycle are small (but they are present at the
level which one expects from the observed cloud cover variations...
about 0.1°C). Second, there is a lag between the response and the
forcing. Typically, one expects lags which depend on the time scale of
the variations. The 11-year solar cycle gives rise to a 2-year lag in
the 0.1°C observed temperature variations. Similarly, the response to
the 20th century warming should be delayed by typically a decade.
Climatologists know this very well (the IPCC re****t, for example,
includes simulation results for the many decades long response to a
"step function" in the forcing, and climatologists talk about "global
warming commitment" that even if the CO2 would stabilize, or even
decrease, we should expect to see the "committed warming", e.g., Science
307), but L & F are not climatologists. They are solar physicists, so
they may not have grasped this point to the extent that they should
have.
Incidentally, this is not unlike a very well-known effect from everyday
life. Even though the maximum radiation from the Sun is received near
noon time, the maximum daily temperatures are obtained a few hours later
in the afternoon. If we were to correlate the falling radiation between
say noon and 3 pm (or between June 21 and July-August), to the
increasing temperature over the same period, we would conclude that
solar radiation causes cooling! This is exactly what L & F are doing.
They are ignoring the fact that over the 20th century, solar activity
increased tremendously (see the third figure below). So, even though the
2001 maximum is weaker than the 1990 maximum, we are still paying for
the extra heat absorbed over several decades, from the middle of the
20th century.
Figure 3: Tremendous increase of solar activity in the last 100 years
In fact, if you look at the total heat in the oceans, you will see that
from 2001 it actually decreased! (Well, recently, after the inconvenient
buoy data was removed, the heat content stopped increasing.) This lower
heat content should start to cause a prolonged cooling, assuming the
solar activity will remain at the 2001 level or lower.
Moreover, if you look directly at the mechanism through which solar
activity affects climate, that is, the amount of cloud cover, you do see
that the amount of cloud cover decrease in the 2001 maximum is smaller
than the decrease in 1990. As it should!
Thus, when you look at the whole picture, there are certainly no
inconsistencies in the solar/climate picture. Au contraire.
And that's Nir's memo.
For criticisms written by others, see Climate cuttings 7 and Warwick
Hughes. A new do***ent by Henrik Svensmark and Eigil Friis-Christensen
is a reply to the article by Lockwood and Fröhlich. Many graphs are
extended up to 2007. The figure 2b is a particularly impressive
agreement between cosmic rays and temperature although one had to
subtract El-Nino effects, the North Atlantic oscillation, volcano
aerosols, and a linear trend to make it that good.
Warmest Regards
Bonzo
"CO2 variations show little correlation with our planet's climate on
long, medium and even short time scales." R. Timothy Patterson,
Professor Of Geology, Director Ottawa-Carleton Geoscience Center,
Carleton University, Canada
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