Geoengineering or not?
David Hawkins
Jim Fleming
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Charles A. Dana Professor of Science, Technology, and Society, Emeritus, Colby College
"Everything is unprecedented if you don't study history."
Michael MacCracken
Not an answer to the question, but a comment on the proposed explanation for what is said to be happening:
If the clearing of the forests made it warmer and this were purely an albedo effect, at least during the warm half of the year, forested land is generally darker than agricultural land, so the direct albedo difference would seem likely to have been operating in the opposite direction (assuming one measures the temperature in a shaded area--of course, if the sunlight strikes you instead of the trees, you will feel warmer). What might well be going is an effect due to the water budget, with a forest putting a good bit more of the incoming energy into evaporation than into warming, whereas with cleared land there is no way to be pulling so much moisture out of the ground and so a greater fraction of the incoming energy is going into warming.
For the winter season, snow cover on cleared land would likely create a brighter surface than snow onto a forest, even if trees have no leaves, so a forest is likely a bit warmer than out on cleared land, even though there is less incoming solar energy during the winter (of course, if you go out onto open land, the sunlight striking you might make you feel warmer, and would be the same for a thermometer, again the reason for comparable measurements being made in the shade).
As to the question, this does seem to raise the question about
whether the motive of the effort matters. What about cutting down
a forest to get a good view or to grow crops versus cutting it
down to feel warmer (or so more often the sunlight strikes you)?
So, what about, however, denuding the Amazon?
And then there is the question of scale--the definitions usually include a provision that to qualify the effect has to be global or at least very large scale--so cutting an acre of forest would not qualify whereas cutting down all forests would?
I'd suggest that lots could qualify if one wants to use the term that way, but what we are talking about is doing something with the intent of noticeably counter-acting human created GHG induced climate change.
Mike MacC
Hawkins, David
Sent: Monday, February 6, 2023 1:49:22 PM
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Subject: Re: [geo] Geoengineering or not?
Andrew Lockley
Jim Fleming
Ekholm pointed out that over the course of a millennium the accumulation in the atmosphere of CO2 (carbonic acid) from the burning of pit coal will “undoubtedly cause a very obvious rise of the mean temperature of the Earth.” He also thought this effect could be accelerated by the “digging of deep fountains pouring out carbonic acid” or perhaps decreased “by protecting the weathering layers of silicates from the influence of the air and by ruling the growth of plants.” By such means Ekholm pointed to the grand possibility that it might someday be possible “to regulate the future climate of the Earth and consequently prevent the arrival of a new Ice Age.” In this scenario, climate warming by enhanced coal burning would be pitted against the natural changes in the Earth's orbital elements or the secular cooling of the sun. Ekholm concluded, “It is too early to judge of how far Man might be capable of thus regulating the future climate. But already the view of such a possibility seems to me so grand that I cannot help thinking that it will afford Mankind hitherto unforeseen means of evolution.”
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David Hawkins
E. B. Hunt, “Terrestrial Thermotics,” p. 542, (1849), as published in Buchanan’s Journal of Man, Vol. 1, 1850, Jos. R. Buchanan, editor
In an introduction, the editor of the volume where the paper was reprinted rhapsodized about the implications for future climates:
“The following profound and able paper was presented at the
second meeting of the American Association of the Advancement of Science, held
at Cambridge, Mass., Aug., 1849. As a simple, beautiful, and interesting exposition
of the early history of the world, when the flowers of summer bloomed over the
lands now consigned to the changeless desolation of icebergs and snowdrifts, it
cannot fail to interest all readers. The doctrines of this paper would tend to
the conclusion that we might possibly reverse the cooling process which has
produced our frigid Arctic climates. If the extension of the frigid zone has
arisen from the consumption of the elements of the atmosphere --- why might not
this oxidating process be reversed by decomposition, and the atmosphere again
increased in bulk and raised in temperature by the liberation of gases. The decomposition
of carbonic acid has been proved by Mr. Vaughan. If, in addition to the oxygen supplied from
such a source, we could find an adequate source of nitrogen, the ancient atmosphere
might possibly be regenerated, and the blessings of agriculture, prosperity,
and civilization be carried over the desolate hyperborean regions of America,
Asia, and Europe. ---Editor.”
David