Up to: Progress and its Sustainability
Avoiding Global Warming
It may not be necessary to make large efforts to avoid global warming.
First of all, it may not happen, and, secondly, it may not be harmful
if it does. The warming observed to date, which may or may not be
partly due to human activity, seems to have been beneficial in
lengthening growing seasons in temperate and northern climates. Since
serious efforts to reduce CO2 emissions or to increase
CO2 sinks are likely to be extremely expensive, for the
present it is best to wait.
On this point it is necessary to be blunt. The strongest advocates of
reducing CO2 think we use too much energy quite apart from
questions of supply and possible side-effects. Therefore, they look
for reasons to solve the global warming problem by reducing
civilization. Not all think that way, but such ideas are providing a
lot of the force behind the campaign, e.g. as proposed in former
Vice-President Gore's book, Earth in Balance and his recent
movie An inconvenient truth.
The Kyoto agreement involves the developed countries undertaking to reduce
their CO2 emissions to 1990 levels by 2010. (I think I remember
it correctly.) The backward countries do not agree to do anything, and
China and others will increase their emissions enormously. Fortunately,
the US Senate has not ratified the agreement.
Here's a somewhat revealing quotation from early in the "energy crisis".
``We can and should seize upon the energy crisis as a good excuse and
great opportunity for making some very fundamental changes that we
should be making anyhow for other reasons.'' - Russell Train,
Science 184 p. 1050, 7 June 1974.
Train was EPA Administrator at the time, and after that became head of
the World Wildlife Fund.
Nevertheless, it still may turn out that CO2 emissions are
giving rise to substantial global warming and that is harmful. I
think nothing very costly will be done unless and until actual harm is
experienced. In that case, what can be done?
- Replace coal, oil and natural gas plants for generating
electricity by nuclear plants.
Replacing coal burning plants should
get the highest priority, because they generate the most CO2 per
unit of energy generated, and because their emissions cause substantial
lung damage. (It is interesting that some the proposers of
"carbon taxes", both in America and Europe, want to include nuclear
energy as a target of the "carbon tax". There is clearly more on
the agenda than global warming.)
Solar energy in various forms would also
work, but it seems to be
very costly in spite of the best efforts of its advocates.
- Unfortunately, generating electricity without putting CO2 into
the atmosphere probably wouldn't be enough if the global warming problem
is serious. The next step is to use nuclear produced electricity for
space heating and other direct uses of heat.
- The most difficult step is to use electricity for automotive
transportation. In spite of very vigorous research, batteries
capable of giving electric cars reasonable range have not been
developed, although there seems to be no law of nature making
them impossible. Here's a scheme
that would ameliorate the problem even if lead-acid
batteries had to be used.
- Another approach is to use hydrogen generated
by splitting water with (say) nuclear electricity. Cars powered
by liquid hydrogen have the potential of matching the performance
of gasoline powered vehicles. The hydrogen tanks will need three
times the internal volume of gasoline tanks and still greater
external size because of the insulation required. BMW has demonstrated
a liquid hydrogen powered internal combustion engine car. Schemes for
using hydrogen in other forms than liquid are unlikely to have
the required range. See the
page on hydrogen for more details.
Some people seem to believe that using hydrogen gets more energy. It only
provides a way of using nuclear or solar energy. Apart from
its possible use to reduce global warming, hydrogen it likely to be the
solution for personal transportation when petroleum runs short.
- Rather than putting all the effort into reducing carbon
emissions, it may be more cost-effective to put some effort into
removing more CO2 from the atmosphere. Plants remove CO2, but only
while they are growing. A climax forest may be in equilibrium; apparently
the exact facts are not yet known.
What will surely work is to cut down forests, not burn the wood and
replant the forests with fast growing trees. When these trees reach
a size at which their growth slows, they would be cut again. Back in the
carboniferous era, trees fell into
swamps which evidently provided a reducing environment. The oxygen
and hydrogen in the wood were re-emitted into the atmosphere, and the
carbon became coal. This process will work for us too (to reduce
CO2 (it takes too long to make coal) if it proves
necessary. Canada and Siberia have large forest areas not being
used for other purposes.
Perhaps Brazil might be persuaded that the trees being cut down in
the Amazon to make more farmland should not be burned. Persuading them of
that is likely to be easier than persuading them to forgo the farmland.
An article
Resurgent Forests Can Be Greenhouse Gas Sponges from
Science of 1997 July 18 discusses the effect of new
forest growth on removing CO2. It doesn't discuss harvesting the
forest repeatedly.
Research is needed
Some have criticized my including the above proposal to repeatedly harvest
forests on the grounds that it is not worked
out in detail. It would be a major research project to work out any
such proposal in enough detail
to determine how much it would cost, how much CO2 would be
removed,
and what other good and bad effects might occur. For example, one
would have to
study under what conditions the wood harvested would
just oxidize again. This might depend on soil and latitude. How
fast the trees would grow depends on latitude and might be enhanced
by fertilization. I suspect the studies would cost many millions
of dollars and take many years. The problem may be of sufficient
magnitude to justify this.
- There are also various schemes for getting the ocean to extract more
CO2 from the atmosphere such as iron fertilization. This was
proposed, then refuted and then rehabilitated technically by people
who were against actually using it. Here's an
amusing reference. The researcher, Kenneth Coale, ends up saying
"I feel compelled to carry out this research in a way which is
environmentally responsible." Presumably, he is one of those, along
with Stephen Schneider, who
are dubious about any form of
"global engineering. An Australian
study reported in 1999 confirms that iron fertilization can be
expected to have substantial effects in the Southern Ocean.
Here's an article
Climate Controls by Gregory Benford, a physicist at
UC Irvine and science fiction writer. He describes many possibilities for
mitigating global warming. His article is more comprehensive than this
one.
Up to: Sustainability FAQ
Send comments to mccarthy@stanford.edu. I sometimes make changes
suggested in them. -
John McCarthy
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