Terry Alden
Essayist Writer and Lecturer
340/227-5332 (cell w voice mail)
ter@technosophy.com
Project: Solar Shield -- A "Curtain of Particles" to Shield the Planet
Terry Alden
©2007, 9/18
This is a serious proposal for creating a variably transparent curtain of fine particles in the upper atmosphere of the planet Earth for the purpose of off-setting the effects of global warming. The particles would be of some suitable reflective material, an inert powder, which would spread through a layer of the upper atmosphere to envelop the planet and lower the amount of incoming sunlight reaching the surface by some controlled amount. More sunlight would be reflected back into space than is occurring naturally now. The amount of needed increase in the reflectivity would be determined by running the same computer models which currently model global weather. These models already take into account the incoming solar energy and could project global cooling effects for specific increases in planetary albedo.
The albedo (geometrical) of the earth is currently about 37%. An albedo of zero would apply for a perfect "blackbody" where all incoming energy is absorbed and none is reflected. An albedo of unity applies for a perfect "mirror" where all incident energy is reflected and none is absorbed. So currently for the earth, about 37% of the radiation from the sun is being reflected from the planet back into space. If this were increased by as little as a few percentage points, to around 40% let's say, the reduction in incoming solar energy could be sufficient to offset the warming due to the accumulation of greenhouse gases.
This does not imply that we should not endeavor to reduce greenhouse gases while also increasing the planetary albedo, but that both strategies would work together to slow global warming and avoid its worst effects. At the very least, it would give us more time to get greenhouse gas emissions under control.
We know that this strategy would work in principle because there have been volcanic eruptions and asteroid strikes on the earth in the past which have, on a more drastic and uncontrolled level, caused calamitous sun blocking effects associated with mass extinctions of species and ice ages. The challenge is in working out the details and in delivering perhaps thousands of tons of appropriate particulate material to the upper atmosphere at just the right altitude so that it would mix with and disperse throughout the air layer at that altitude and not fall back to the earth's surface too quickly.
Experts in various fields would work out the specific details:
What material should be used for the
particles?
Materials scientists and physicists would choose the best substance based
on reflectivity when dispersed as particles in the thin atmosphere at high
elevation above the earth's surface. It would also have to be a substance
sufficiently inexpensive and easily available in large quantities. Exactly
how much material would be needed is a calculation physicists would make.
The addition of particles to the upper atmosphere would not necessarily be permanent. There could be a slight increase in dustfall from this material but probably not very noticeable at the earth's surface, given the current dustfall from space and human activity. The material used would have to be non-toxic since it would eventually fall out of the atmosphere. One material that comes immediately to mind, and should be available in large quantities, is volcanic ash. This material, in excessive quantities, created "global winters" in the past. It was the explosion of a portion of just one mountain, Krakatoa, which is believed to have caused an ice age in the distant past. Volcanic ash is probably relatively safe in terms of toxicity also but might cause changes in the pH of water supplies.
How would the substance be delivered to
the upper atmosphere?
The particles could be released in explosions of shells carried to
the proper altitude above earth's surface by the same rockets (ICBMs) used to
deliver nuclear warheads, and also ejected or sprayed from high-altitude planes
in a manner similar to "sky writing," although planes may not reach
sufficient altitude that the particles released there would not fall back to
earth too quickly to be useful. The particles would be delivered to just the right altitude and in just the right
quantities over time to maximize the cooling offset to global warming without
causing major deleterious or unpredictable effects. All nations possessing
rocket technology could contribute to this peaceful use and the vehicles are
already in existence; they would not need to be manufactured. Many of them
are already fueled and ready to fly. It would be literally "turning
swords into plowshares."
Additional Considerations
The internationally cooperative and long-term effort should
ideally be undertaken under the auspices of the United Nations, with all nations
possessing the required technology participating. It is conceivable,
however, that certain nations, like Canada and Russia, would not be very eager
to take part because it may be that they stand to gain a great deal by allowing
global warming to remain uncontrolled.
Warmer temperatures globally should lead to more cloudiness as water and air temperatures increase from global warming. Clouds are also very good for reflecting the sun's rays back out to space, so there should be some global warming offsetting effect from the increase of the earth's albedo by increasing global cloud-cover. Mathematical computer models should also predict such "natural" increases of global albedo due to evaporating more water into the atmosphere. The solution of adjusting the earth's albedo with high-altitude particles would work along with any natural offsetting processes which may concurrently take place.
Terry Alden
Essayist Writer and Lecturer
340/227-5332 (cell w voice mail)
ter@technosophy.com
Terry Alden is a writer living in Northern California. He received
his degree in Planetary Sciences at MIT
and is the author of essays on
subjects ranging from ancient astronomy to modern parapsychology.
He plans
to publish these with additional material in a future book, Occam's
Electric Shaver.
Occam's Electric Shaver
The following short article appeared in the January/February 2010 edition of Technology Review (pp. 14-15). It outlines the steps which need to take place immediately and confirms that the approach to offsetting global warming advocated on this page is feasible and important enough to begin researching without further delay:
Why Geoengineering?
M. Granger Morgan Explains Why We Must Study the Consequences of Shading the Earth.
by M. Granger Morgan, Head
Department of Engineering and Public Policy
Carnegie Mellon University
Scientists already know how to cool the planet
quickly. The secret is geoengineering: specifically, using very fine
particles in the stratosphere to reflect sunlight (see "The Geoengineering
Gambit," p. 50). The direct cost of shading the planet this way could
be less than a few hundredths the cost of reducing carbon dioxide
emissions. If reflecting sunlight is fast and cheap, why struggle with all
the problems of collective action to achieve emission reductions? Why not
wait until we have a climate problem and then simply fix it?
Over the past half-century, people have "fixed" a number of other problems with environmental implications. We have reversed rivers in Russia, inadvertently destroying the Aral Sea in the process; we have built roads and encouraged farming in tropical areas, inadvertently depleting the soil and destroying millions of acres of rain forest. If, with typical shortsightedness and hubris, we count on geoengineering to save the planet, can we be sure that the outcome will be what we intend?
Despite the mistakes of the past, the answer is not to treat geoengineering like chemical and biological weapons research, surrounding it with a global taboo. If a country experiencing a prolonged drought, for example, seeks to engineer the planet's climate unilaterally, we will need to be familiar with the potential consequences in order to muster informed counterarguments. And if our more extreme climate-change predictions become reality and a sudden climate emergency puts billions of people at risk, the world should not find itself collectively embarking on a crash program of geoengineering in ignorance.
We need to know much more about geoengineering. Until recently, most scientists and research managers have been reluctant to do research in this area, for fear that knowing how to engineer the climate would encourage people to do it. But today, the risks of avoiding research outweigh the risks of pursuing it.
We need to take two steps now. First, we should establish a loosely coordinated international program aimed at researching how to shade the planet, how much it would cost, and what the intended and unintended effects would be. This research should also address what the rising atmospheric concentration of carbon dioxide means for terrestrial and oceanic ecosystems, since reflecting sunlight will do nothing to stop it. About one third of emitted carbon dioxide is absorbed by the oceans, which become more acidic as a result; they are already 30 percent more acidic today than they were in preindustrial times. If current emissions continue, most coral reefs could be gone by the end of the century, along with all the ecosystems they support.
Second, we need to get the foreign-policy community working on a collective approach to regulating geoengineering. My colleagues and I have started that process with two international workshops involving climate scientists and foreign-policy experts. Further informal discourse will lay the groundwork for a formal framework.
[Emphasis highlight colors added by T. Alden.]