Okay, before we start, let me just say that, over the next few days, I’ll be devoting a number of posts to geoengineering. Why? Because governments around the world are considering employing it, many of the proposals are extremely risky, and I want you to know what’s going on before it’s too late to stop it.
In case the term is new, geoengineering has been defined as: “the deliberate large-scale manipulation of an environmental process that affects the earth’s climate, in an attempt to counteract the effects of global warming.”
Scientists and engineers have proposed two main geoengineering strategies: solar radiation management (SRM) and carbon-dioxide removal (CDR).
We’ll start with SRM.
The question that inspired the solar-radiation-management strategy might have originally been framed something like this: Given that global warming is caused by solar heat getting trapped in the atmosphere, why not redirect some of the Sun’s rays back into space before they have a chance to overheat the Earth?
In response to that question (or one like it), scientists and engineers have come up with plans for reflecting and deflecting sunlight from: (1) the planet’s surface, (2) various levels of the atmosphere, and (3) outer space.
I should warn you that pondering these plans to reengineer the Earth via SRM will either tend to relieve your anxiety about global warming or elevate your blood pressure, depending on the extent of your faith in technology. While I generally fall into the group prone to hypertension on these matters, I think a few of the land-based methods—ones that simply make surfaces more reflective (or increase the Earth’s albedo in science-speak)—are probably pretty benign. One such idea is to roof and pave with white or very light materials.
Other ideas for increasing the surface reflection of the Earth are more worrisome, however. One that some geoengineers have been floating (sorry, but I couldn’t resist the bad pun) is to set large Styrofoam blocks adrift in the ocean. Offhand, Styrofoam icebergs seem like a bad idea. The plastic would certainly breakdown over time and be swallowed by birds, fish, sea mammals, and other ocean fauna. Precisely how the ingested plastic would affect them would vary somewhat from one species to another, but whatever the impact, it wouldn’t be good. (I just looked in a book by the National Research Council to get a sense of the impact. It said that between one and two million birds and 100,000 sea turtles and marine mammals die each year from eating or getting tangled in Styrofoam and other plastic debris. In the case of sea turtles, ingesting Styrofoam “can cause intestinal blockage, release toxic chemicals, reduce nutrient absorption, reduce hunger sensation, inhibit feeding and mating activity, diminish reproductive performance by leaving the turtle unable to maintain its energy requirements and cause suffocation, ulceration, intestinal injury, physical deterioration, malnutrition, and starvation.”)
In any case, dumping Styrofoam blocks into the ocean and painting roofs and other things white are a couple of SRM methods for reflecting solar radiation from the Earth’s surface back into space. But SRM isn’t confined to the Earth’s surface. Some SRM methods do their work in outer space. So let us zoom out to the heavens to take a look at the bizarro-a-go-go geoengineers’ plan to rocket and release reflective disks into the cosmos. The big idea here is to prevent some sunlight from reaching the Earth by putting mirrors “into a gravitational balance point” between the Earth and Sun. Sounds pretty cool, doesn’t it? So why do I denigrate this product of thermo-reflective brilliance? Well, for one thing, the Sun is mighty big, so it would take a whole lot of disks to have a significant impact. How many? According to a comprehensive report on geoengineering by Britain’s Royal Society, a reduction of about two percent in the Earth-striking radiance of the Sun would require about three million square kilometers (approximately 1.2 million square miles) of reflective area in space, so we’re talking about trillions of disks here. More precisely, this scheme would require “a swarm of around ten trillion extremely thin high-specification refracting disks.” Each disk would be “about 60 cm [around 24 inches] in diameter, fabricated on Earth and launched into space in stacks of a million, one stack every minute for about 30 years.”
One stack a minute would come to 1,440 blastoffs per day. By my calculations, it would take less than twenty years to rocket ten trillion disks to their outer space destination. (Here’s my math: Ten trillion disks—divided by the product of one million disks per launch, times 1,440 launches per day, times 365 days per year—equals 19 years.) Maybe the Royal Society is factoring in schedule disruptions of one kind or another that would require additional launches, or maybe my math is wrong, or maybe there’s some other variable that figures in somehow; but no matter how you slice it, it would take one heck of a lot of launches. The cost would be astronomical, and the whole project would be counterproductive because rockets emit black carbon (a.k.a., soot), and black carbon does a dandy job of absorbing sunlight and heating up the atmosphere. According to a study by scientists working for the Aerospace Corporation (rocket scientists, no doubt), just 1,000 launches per year “would create a persistent layer of black carbon particulate in the northern stratosphere that could cause potentially significant changes in the global atmospheric circulation and distributions of ozone and temperature.” (Recall that the plan calls for more than 1,000 launches per day!) After ten years “of continuous launches, globally averaged radiative forcing from the black carbon would exceed the forcing from the emitted CO2 by a factor of about 140,000. . . .”
In case the term “radiative forcing” doesn’t ring a bell, here’s a succinct explanation from MIT News: “When there’s more energy radiating down on the planet than there is radiating back out to space, something’s going to have to heat up.” Of course, the whole point of putting all those mirrors in space would be to reduce the amount of energy radiating down on the planet, but the radiation that did make it—and that would be most of it—would be trapped all the better by the black carbon put into the atmosphere by all those rocket launches.
Had enough? No? Well then, while we’re on the subject of imaginative, spaced-based (read: looney-tune) ideas, what would you think about putting a Saturn-like ring around the Earth’s equator? I scoff, I smirk, I snark, but I shouldn’t because that idea first appeared in a peer-reviewed scientific journal in 1991, and has received serious consideration—or, at least, been discussed now and then—ever since. The proposed equatorial ring, comprised of about two billion tons of dust and shepherded by satellites, would cool the Earth by casting a giant shadow on the tropics in winter. How would the dust get out there? It would be injected into space from the Earth, the Moon, or nearby asteroids. What, pray tell, could possibly go wrong with a simple plan like that? Well, for starters, a giant shadow on the tropics, for months on end, would affect tropical photosynthesis. Is it just me, or does that sound a mite risky to you, too?
And speaking of enormous risks, we’ll be taking up some more examples of solar radiation management next time, including a plan devised by the “father of the hydrogen bomb” (Dr. Strangelove himself!), Edward Teller.
So please join me for the next installment of: What You Always Wanted to Know About Geoengineering but Were Afraid to Ask.
 “Geoengineering.” Oxford Dictionaries. http://oxforddictionaries.com/definition/geoengineering
 Nordhaus, William. 2013. The Climate Casino: Risk, Uncertainty, and Economics for a Warming World. New Haven, CT: Yale University Press.
 Vergano, Dan. “Can Geoengineering Put the Freeze on Global Warming?” USA Today. Updated February 25, 2011. http://www.usatoday.com/tech/science/environment/2011-02-25-geoengineering25_CV_N.htm#
 National Research Council: Committee on Sea Turtle Conservation. Decline of the Sea Turtles: Causes and Prevention. Washington, DC: National Academy Press, p. 114.
 Vergano, Dan. “Can Geoengineering Put the Freeze on Global Warming?”
 The Royal Society. 2009. Geoengineering the Climate: Science, Governance and Uncertainty. RS Policy Document 10/09. London: Royal Society.
 Ross, Martin, Michael Mills, and Darin Toohey. 2010. “Potential Climate Impact of Black Carbon Emitted by Rockets.” Geophysical Research Letters, Vol. 37, no. 24.
 Chandler, David. “Explained: Radiative Forcing.” MIT News. March 10, 2010. http://web.mit.edu/newsoffice/2010/explained-radforce-0309.html
 Mautner, M. 1991. “A Space-Based Solar Screen Against Climate Warming.” Journal of the British Interplanetary Society 44, pp. 135-138; The Royal Society. 2009. Geoengineering the Climate: Science, Governance and Uncertainty. RS Policy Document 10/09. London: Royal Society.
 The Royal Society. 2009. Geoengineering the Climate: Science, Governance and Uncertainty. RS Policy Document 10/09. London: Royal Society, p. 32.