From: userDHAL@mts.ucs.UAlberta.CA (David Halliwell)
Newsgroups: sci.skeptic
Subject: Re: Solar cycle vs. CO2 for greenhouse effect
Date: Wed, 29 Jul 92 21:27:10 GMT
Organization: MTS Univ of Alberta     

In article <1992Jul15.024633.24716@murdoch.acc.Virginia.EDU>, lfoard@Turing.ORG (Lawrence C. Foard) writes:
> 
>I'm still looking for any references for studies of the greenhouse
>effect that don't ignore the solar input. I have trouble believing
>scientists would ignore the obvious explanation, but then there was
>cold fusion :)
> 
>-- 
 
    Our news feed on this machine is quite a bit behind, and I just
started to subscribe to sci.skeptic. When Lawrence originally brought
this question up (a month ago?), I posted a response which appears
to have only gone to sci.environment. Forgive me for the likely lack of
continuity, but here is my old response. The context relates to the
discussion as it had developed on sci.environment and sci.geo.meteorology.
 
 
<------- start of included text -------->
 
 
In  article <1992Jul11.014911.7813@murdoch.acc.Virginia.EDU> 
    lfoard@Turing.ORG (Lawrence C. Foard) writes:
>In article <1992Jul8.025153.6792@meteor.wisc.edu> tobis@meteor.wisc.edu (Michael Tobis) writes:
>>
>>Evidence? Seventeen broadly independent models reach broadly the same
>>conclusions. Models are far from perfect, and indeed not adequate to
>>the task of determining which regions will be most strongly impacted.
>>Nevertheless, they do successfully reproduce storm tracks, seasonal
>>cycles, and paleoclimates, thus providing independent verification.
>>There is much room for improvement, to be sure, but "garbage" is not a
>>remotely sensible criticism.
> 
>I recently attended a lecture on sun and star spots, it was pointed out that
>the global warming data much more closely follows solar output than CO2
>levels.  Are there any studies that include the changing solar output and
>still find that the CO2 levels are needed to explain the current climate
>changes? 
> 
> The effect of solar output on the climate is quite dramatic, the
>"mini ice age" was a period when the sun had virtually no sun spots.
>If these obvious effects are being ignored in the models they are
>very seriously flawed and virtually meaningless.
> Whats needed is an estimation of the proportion of global warming
>caused by the sun and the portion caused by CO2. It may be very
>unPC, but from what I've recently seen I have some serious doubts
>about the significance of the greenhouse effect.
>
 
     Sigh! It quite amazes me that people are willing to question the
accuracy of long term temperature measurements, asking questions about
the reliability of readings taken 100 years ago, yet accept without
question the use of sunspots as an indicator of solar output!
 
    To begin, use of solar variability in models requires a source of
data on solar output. As was said earlier in this thread, garbage in/
garbage out. People have indeed been counting sunspots for hundreds
of years. Sunspots have indeed been *correlated* with a wide variety
of climatological cycles. Lawrence is correct in stating that the
Little Ice Age (roughly in the late 17th and early 18th centuries?)
was a considerably cooler period which coincided with the Maunder
Minimum (a period of little or no sunspot activity). Of course, our
knowledge of that being a cooler period is uncertain, since the
instrumental record is very scanty. However, the Thames River in
England would freeze over regularly in the winter, and that doesn't
happen now.
 
    To model this past climate we would need to know the actual solar
output at the time. Is this available? No. Measuring solar output is
most easily done *above* the atmosphere, and we have only been able to
do this for the last couple of decades, using satellites. Before this, 
relatively unreliable methods at the ground surface were used, and these
are not of sufficient accuracy to detect small variations in solar output
that have been *speculated* to arise due to sunspot activity.
 
    The Solar Max satellite was launched around 1980 for the specific
purpose of monitoring solar output. The name, I believe, arose because
it was timed to be sent up for the maximum in sunspots in 1980. The
satellite malfunctioned, and was repaired by a crew on the space shuttle,
going down in infamy as the first in-space repair of a satellite. Solar
Max died a fiery death in either 1990 or 1991. (I can't remember which.)
As a result, we have about 10 years of reliable data that can be used to
address this question.
 
    I don't have the reference handy, but around 1985 or so I read a
paper in which someone discussed the first few years of Solar Max data,
and tried to model the temperature variation that would result from the
observed solar output variation. The solar output (basically 1368 W/sq.m)
showed a decline of only 1-2 W/sq.m over the four or so years discussed.
This small variation in solar output only led to changes of a few
*hundredths* of a degree in the model (a one-dimensional energy balance
model). The paper concluded that the *observed* solar variabilty was
not sufficient to cause significant climatic variability on its own.
If solar activity *is* affecting the climate (as so many statistical
studies have suggested), then it is doing it by some means other than
just the direct effect of energy output. I haven't seen any more recent 
work with more sophisticated models or the longer data set which should 
now be available. If anyone knows of any, I would very much like to
have the reference.
 
    In the past week or so, I have referred to a paper in some of my
other posts.If you take a look at:
 
       Hansen, J, D Johnson, A Lacis, S Lebedeff, P Lee, D Rind, and
       G Russell (1981)  "Climate Impact of Increasing Atmospheric 
       Carbon Dioxide", SCIENCE 213 (4511), pp957-966.
 
you will find that they attempted to model the last 100 years of
temperature records using CO2, solar output variations, and volcanic
activity as forcing mechanisms. Where did they get solar output data?
They used a theoretical model involving umbra/penumbra ratios, which
gave them a considerable inproved fit over the model without solar
forcing variations. Why did they use this particular theoretical
model? Because out of the several theories they tried (I think some
indcluded sunspot numbers), it was the one that gave the best fit.
Ultimately, the climate model provided statistical explanation of
over 90% (if I remember correctly) of the observed temperature record,
when CO2, solar, and volcanic forcing was included. And *yes*, they 
needed CO2 in the model to fit the slow rise in temperature seen
since 1880. At the time of the paper, Solar Max data obviously
wasn't available. I don't know if the theoretical solar output
estimates have been compared to later data.
 
    So, there you have it. IMHO, sunspots and climate remain a
*theory*, suggested by statistical correlation, but unsupported by
our current knowledge of the physics involved or our ability to
model the climatic response to *observed* changes in solar output.
Many people are continuing research into the sunspot/climate link,
for good reason. 
 
    On the other hand, our knowledge of the physics and attempts to
model it *do* suggest that increasing CO2 will lead to a warmer
climate.
 
 
>> [Michael discussing climate models] 
> 
>Unless they take the sun into account (I don't know if they do or not),
>they are worthless.
 
    Sigh! Model with normal CO2 gives one temperature, with doubled CO2
it is warmer. This result is not worthless. It suggests that *with all
other external factors being constant*, increasing CO2 will lead to
warmer temperatures. For this sort of work, you *want* to keep other
factors constant. Change things one at a time.
 
    Solar output becomes important when trying to explain *past*
observations, and make specific predictions for specific times in
the future. As has been stated before, the reason it is hard to see
any CO2 signal in the last 100 years is because *many* other factors
are causing variability in global temperatures. Solar output may
be one of them. However, heading into the 1990s, the expected rise
due to CO2 should be becoming larger than our past observations of
variability from other causes. This is also discussed in the Hansen
et al paper I referred to above.
 
    A great number of people keep saying "where is the success in
modelling past climates?" They should think a little bit about just
what data is required 1) for input, 2) for verification of the
simulations of the past. It is possible to fiddle with the input to
improve the fit, but that doesn't mean that you have the physics
right. After all, I could give you a program that will reproduce
the last 100 years of global temperature data *exactly*, and only
take a second of time on your PC. It's just that the program won't
have any basis in reality, or any use in predicting future trends.
The numbers could just as easily be whatnot production from the Acme
Widget Co.
 
 
Dave Halliwell            |    "So once you know what the question 
Department of Geography   |      actually is, you'll know what the
University of Alberta     |       answer means"
Edmonton, Alberta.        |       - Douglas Adams