From: tobis@meteor.wisc.edu (Michael Tobis)
Newsgroups: sci.environment,sci.geo.meteorology,sci.skeptic
Subject: Re: Lawyer's science vs. unbiased presentation of the facts
Date: 24 Jul 92 18:46:52 GMT
Organization: University of Wisconsin, Meteorology and Space Science

My final word for a while. I promise.

In article <1992Jul22.201920.6764@techbook.com> szabo@techbook.com (Nick Szabo) writes:
>
>There are two figures of merit, rate of change and absolute magnitude.
>Tobis has claimed that rate of change is the most important problem with 
>global warming, and I am refuting that. 

I don't believe I ever said it was the "most important".

Both the rate of change and the expected magnitude of the change are large
enough to be cause for concern.

I mentioned that the likely global temperature at the end of the next century
is higher than any seen in the last 30,000,000 years, and you continued
to bring up rates of change in response.

I did say the rate of change was higher than any sustained change in history,
a few months ago. This was erroneous. The rate of change is comparable
to the largest known sustained changes, though.

Volcanoes and El Nino are somewhat off the subject, as their impact is
brief in the first case and oscillatory in the second.

>I agree we should start looking, in fact we _are_ looking, from fission
>power to methane/biofuels proposals.  What I disagree with is using 
>global warming as an excuse to put major taxes on fossil fuels, based on
>computer models and a science that, without reflecting negatively on
>any of its practioners, has not been able to successfully predict the
>climate.  What I _doubly_ object to is "carbon taxes" as they have
>actually been implemented: directed against targets of opportunity, 
>including nuclear power and small business.

OPINION:
If carbon taxes have been proposed or levied against the nuclear industry, 
I would agree with you on this point. Does anyone out there have any details
about this?

Taxes on actual emissions of greenhouse gases seem to me to be the least
onerous form of social constraint on those emissions, far better than
assigning non-transferable limits on each individual and business.
With taxation proportionate to impact, people pay for what they use rather
than transferring the costs to the society while keeping the benefits.

>  This is the kind of crap
>that happens when we get hysteria and people willing to take advantage
>of hysteria.  We need a massive dose of deep breath and rationality
>if we really want to find out what is going on here, and figure out
>how to respond to it.

Absolutely. What we don't need is obfuscation, or blind belief in
politically motivated articles in non-scientific publications.
Regardless of whether those publications have an interest in
exagerrating or minimizing this or any other environmental issue.

>  Tobis leaves out many relevent facts, and
>lines his critique with hysterical hyperbole; he is not doing the climate 
>or ourselves any service.

Be serious. I can't produce all the relevant facts in a finite space, even
if I knew them. What you call hyperbole is actually scientific consensus.
If it seems like exageration to you, it is because you have read slanted
analyses of the facts in political publications.

Here's my current list of the most important results:

SCIENCE:
* It is certain that the surface temperature of a planet is determined
by the presence of gases which are opaque to frequencies in the range
of the black body emissions that correspond to the radiative balance
with the sun. (among other well determined factors: notably the solar
emissions and the albedo.)

* It is certain that H2O and CO2 contribute about 33 Kelvin to the surface
temperature of the earth under pre-industrial conditions. It is clear that
about 25 % of this is due to CO2. It should be noted that (due to band
saturation) doubling of CO2 will NOT directly produce doubling of CO2 warming,
but somewhat less.

* It is certain that CO2 has increased by about 30 % since preindustrial times.
It is clear that the increase is anthropogenic, and that the anthropogenic
emissions are currently at about twice the annual increase in the atmospheric
burden, with the balance going into the oceans and flora. The rate of
increase of the anthropogenic component has been quite consistently 2%/yr
for a long time. This corresponds to 0.5%/yr increase in total concentration
at the present time. Extrapolation of this curve yields doubled background
concentrations before 2050 and quadrupled concentrations by 2100.

* It is clear that a doubling of CO2 will decrease the transparency of
the atmosphere by an amount equivalent to an increase in solar irradiation
of 4.3 W/m^2. It is clear that this will warm the atmosphere. It is uncertain
by how much the atmosphere will warm because of two effects: warming
is likely to increase ocean evaporation, thus increasing the H2O greenhouse
forcing; warming is likely to change albedo by changing cloud distributions
and snow/ice distributions. Cloud albedo feedback is uncertain in sense,
though probably a mitigating factor in tropical regions at least. Ice albedo
feedback is believed to be exacerbating, though this is debated. 

* It is clear that anthropogenic greenhouse gases provide a larger forcing
than any experienced not only on historical time scales, but even on time
sclaes of much longer duration. The solar/orbital changes that triggered
the geologically recent glaciation onsets and changes in solar forcing
that caused sunspot correlated shifts in climate are known to be smaller.

* Several other gases which are opaque to relevant frequencies are being
emitted by human activity. Collectively, they are approximately equal
in effect to the anthropogenic CO2. Controls on CFC emissions and recent
trends in the methane curve are encouraging. Nitrogen oxides are also 
important in this regard. These effects indicate that the "2xCO2" benchmark
forcing will be reached before CO2 levels actually reach double the
preindustrial concentration. 

* The thermal inertia of the ocean is certain to slow the response of
the system. The exact amount of slowing is unkown, and probably cannot
be adequately represented by a single number because of local effects.
However, the lag in globally averaged warming is expected to be on the
order of 2 or 3 decades. This is good news, in that it mitigates the
suddenness of the changes. However, it also masks the extent of the changes
which we are committed to so far.

* The sensitivity of the global temperature to CO2 forcing is only known
to within a factor of about 4. The observed temeprature record is consistent
with either 1) sensitivity at the low end of the range or 2) sensitivity
within the range combined with other negative forcings (dust emissions from
industry and from rainforest burning have been implicated). The record is
consistent with zero or near-zero sensitivty to CO2 only if some other
warming forcing is involved. Observed temperature increases are statistically
distinguishable from chance variations, but they cannot yet be statistically
significantly attributed to greenhouse warming alone. It has been the 
expectation that this could finally be laid to rest within this coming decade,
although the response to the enormous Pinatubo eruption may complicate this.

* Keeping emissions constant at 1990 levels, as proposed by the treaty
that most nations agreed to in Rio, yields a logistic increase in CO2
concentrations, probably to about 420 ppmv, about 150% of the preindustrial
level. Most analyses indicate that the changes due to such forcing will
be noticeable, but not enormous. However, if emissions continue to grow by
2%/yr until 2010, and are then held constant, total concentrations will
continue to rise rapidly for the next century, reaching doubled levels by 2080,
and asymptoting to about triple preindustrial concentrations in the 22d
century. Thus, if clamping production is believed to be less economically
injurious than drastically reducing it, rapid response is highly effective
in limiting the final impact, whatever it might be. 

* The anthropogenic forcing is large enough that significant climate
change is inevitable, even if the global average temperature does
not change much, because albedo changes to the effect of the balance of
4.3 w/m^2 must occur for 2xCO2. Local changes are certain to exceed
global average changes (by definition of averaging) and changes over
land are likely to be much larger than changes over the ocean because
of the smaller thermal inertia of the continents.

OPINION:
I don't believe this is hysterical, and I do believe that it is the
consensus position of the community as laid out in the IPCC report.

If the worst case surface sensitivity holds and
the worst case emissions continue, the results will be devastating. We
have no control over the first of these two questions, although clearly
we should continue refining our estimates. However, we do have control over 
the level of emissions.

The situation is such that anthropogenic emissions are just changing
from insignificant to profound. Accordingly, the sensitivity of the
outcome to delay in action is surprisingly large. I strongly urge
anyone doubting this point to examine section 1.2.6 of the IPCC reoprt.

I believe that the risk of allowing CO2 emissions to grow is, given
current knowledge, large assuming our best guesses are correct, small
assuming the best case sensitivity, and enormous assuming the worst case.
I believe that capitalism is sufficiently robust as to be able to absorb
a cap on carbon emissions. I reluctantly acknowledge that spreading 
prosperity to less developed parts of the world probably necessitates
the use of nuclear power, given a responsible approach to greenhouse
emissions (unless a breakthrough in energy storage is accomplished, at
which point solar and wind generation may become viable). These are my
opinions.

These are my opinions but the facts are facts.

mt