Vol. 64, No. 2, p. 14-18, 59 DOI: 10.2968/064002006 20 reasons why geoengineering may be a bad idea Carbon dioxide emissions are rising so fast that some scientists are seriously considering putting Earth on life support as a last resort. But is this cure worse than the disease? BY AlAN roBoCk he stated objective of the aerosols into the stratosphere as a means trigger algal blooms; genetic modifica- 1992T U.N. Framework Convention on Cli- to block sunlight and cool Earth. Another tion of crops to increase biotic carbon mate Change is to stabilize greenhouse respected climate scientist, Tom Wigley, uptake; carbon capture and storage tech- gas concentrations in the atmosphere “at followed up with a feasibility study in Sci- niques such as those proposed to outfit a level that would prevent dangerous an- ence that advocated the same approach in coal plants; and planting forests are such thropogenic interference with the climate combination with emissions reduction.1 examples. Other schemes involve block- system.” Though the framework conven- The idea of geoengineering traces its ing or reflecting incoming solar radia- tion did not define “dangerous,” that level genesis to military strategy during the tion, for example by spraying seawater is now generally considered to be about early years of the Cold War, when sci- hundreds of meters into the air to seed 450 parts per million (ppm) of carbon di- entists in the United States and the So- the formation of stratocumulus clouds oxide in the atmosphere; the current con- viet Union devoted considerable funds over the subtropical ocean.3 centration is about 385 ppm, up from 280 and research efforts to controlling the Two strategies to reduce incom- ppm before the Industrial Revolution. weather. Some early geoengineering ing solar radiation—stratospheric aero- In light of society’s failure to act con- theories involved damming the Strait sol injection as proposed by Crutzen certedly to deal with global warming in of Gibraltar and the Bering Strait as a and space-based sun shields (i.e., mir- spite of the framework convention agree- way to warm the Arctic, making Siberia rors or shades placed in orbit between ment, two prominent atmospheric sci- more habitable.2 Since scientists became the sun and Earth)—are among the entists recently suggested that humans aware of rising concentrations of atmo- most widely discussed geoengineering consider geoengineering—in this case, spheric carbon dioxide, however, some schemes in scientific circles. While these deliberate modification of the climate to have proposed artificially altering cli- schemes (if they could be built) would achieve specific effects such as cooling— mate and weather patterns to reverse or cool Earth, they might also have adverse to address global warming. Nobel laure- mask the effects of global warming. consequences. Several papers in the Au- ate Paul Crutzen, who is well regarded Some geoengineering schemes aim to gust 2006 Climatic Change discussed for his work on ozone damage and nucle- remove carbon dioxide from the atmo- some of these issues, but here I present a ar winter, spearheaded a special August sphere, through natural or mechanical fairly comprehensive list of reasons why 2006 issue of Climatic Change with a con- means. Ocean fertilization, where iron geoengineering might be a bad idea, first N HAN o troversial editorial about injecting sulfate dust is dumped into the open ocean to written down during a two-day NASA- J 14 Bulletin of the Atomic ScientiStS MAY/JUNE 2008 sponsored conference on Managing Solar shown large impacts on regional climate, geoengineering schemes and found that Radiation (a rather audacious title) in No- but whether these are good analogs for they reduced precipitation over wide re- vember 2006.4 These concerns address the geoengineering response requires gions, condemning hundreds of millions unknowns in climate system response; ef- further investigation. of people to drought. fects on human quality of life; and the po- Scientists have also seen volcanic 2. Continued ocean acidification. litical, ethical, and moral issues raised. eruptions in the tropics produce changes If humans adopted geoengineering as in atmospheric circulation, causing win- a solution to global warming, with no ter warming over continents in the restriction on continued carbon emis- 1. Effects on regional climate. Geo- Northern Hemisphere, as well as erup- sions, the ocean would continue to be- engineering proponents often suggest tions at high latitudes weaken the Asian come more acidic, because about half of that volcanic eruptions are an innocuous and African monsoons, causing reduced all excess carbon dioxide in the atmo- natural analog for stratospheric injection precipitation.6 In fact, the eight-month- sphere is removed by ocean uptake. The of sulfate aerosols. The 1991 eruption of long eruption of the Laki fissure in Ice- ocean is already 30 percent more acidic Mount Pinatubo on the Philippine is- land in 1783–1784 contributed to famine than it was before the Industrial Revolu- land of Luzon, which injected 20 mega- in Africa, India, and Japan. tion, and continued acidification threat- tons of sulfur dioxide gas into the strato- If scientists and engineers were able to ens the entire oceanic biological chain, sphere, produced a sulfate aerosol cloud inject smaller amounts of stratospheric from coral reefs right up to humans.7 that is said to have caused global cool- aerosols than result from volcanic erup- 3. Ozone depletion. Aerosol particles ing for a couple of years without adverse tions, how would they affect summer in the stratosphere serve as surfaces for effects. However, researchers at the Na- wind and precipitation patterns? Could chemical reactions that destroy ozone in tional Center for Atmospheric Research attempts to geoengineer isolated regions the same way that water and nitric acid showed in 2007 that the Pinatubo erup- (say, the Arctic) be confined there? Sci- aerosols in polar stratospheric clouds tion caused large hydrological respons- entists need to investigate these scenari- produce the seasonal Antarctic ozone es, including reduced precipitation, soil os. At the fall 2007 American Geophysical hole.8 For the next four decades or so, moisture, and river flow in many re- Union meeting, researchers presented when the concentration of anthropo- gions.5 Simulations of the climate re- preliminary findings from several dif- genic ozone-depleting substances will sponse to volcanic eruptions have also ferent climate models that simulated still be large enough in the stratosphere MAY/JUNE 2008 Bulletin of the Atomic ScientiStS 15 impact of pollution in urban areas, but in capitalizing on carbon pristine areas it could be significant. 6. Effects of cirrus clouds. As aerosol ithout market incentives, geoengineering schemes to reflect solar heat are particles injected into the stratosphere still largely confined to creative thought and artists’ renderings. But a few fall to Earth, they may seed cirrus cloud W ambitious entrepreneurs have begun to experiment with privatizing climate formations in the troposphere.11 Cirrus mitigation through carbon sequestration. Here are a few companies in the market to clouds affect Earth’s radiative balance offset your carbon footprint: of incoming and outgoing heat, although California-based technology startups Planktos and Climos are perhaps the most the amplitude and even direction of the prominent groups offering to sell carbon offsets in exchange for performing ocean effects are not well understood. While iron fertilization, which induces blooms of carbon-eating phytoplankton. Funding for evidence exists that some volcanic aero- Planktos dried up in early 2008 as scientists grew increasingly skeptical about the sols form cirrus clouds, the global effect technique, but Climos has managed to press on, securing $3.5 million in funding from has not been quantified.12 Braemar Energy Ventures as of February. 7. Whitening of the sky (but nice Also in the research and development phase is Sydney, Australia–based ocean sunsets). Atmospheric aerosols close to Nourishment Corporation, which similarly aims to induce oceanic photosynthesis, only the size of the wavelength of light produce it fertilizes with nitrogen-rich urea instead of iron. Atmocean, based in Santa Fe, New a white, cloudy appearance to the sky. Mexico, takes a slightly different tack: It’s developed a 200-meter deep, wave-powered They also contribute to colorful sunsets, pump that brings colder, more biota-rich water up to the surface where lifeforms such similar to those that occur after volcanic as tiny, tube-like salps sequester carbon as they feed on algae. eruptions. The red and yellow sky in The related in mission if not in name, stationary carbon-capture technologies, which Scream by Edvard Munch was inspired generally aren’t considered geoengineering, are nonetheless equally inventive: Skyonic, by the brilliant sunsets he witnessed over a Texas-based startup, captures carbon dioxide at power plants (a relatively well- Oslo in 1883, following the eruption of proven technology) and mixes it with sodium hydroxide to render high-grade baking Krakatau in Indonesia.13 Both the disap- soda. A pilot version of the system is operating at the Brown Stream Electric Station pearance of blue skies and the appearance in Fairfield, Texas. To the west in Tucson, Arizona, Global research Technologies, the of red sunsets could have strong psycho- only company in the world dedicated to carbon capture from ambient air, recently dem- logical impacts on humanity. onstrated a working “air extraction” prototype—a kind of carbon dioxide vacuum that 8. Less sun for solar power. Scien- stands upright and is about the size of a phone booth. Meanwhile, GreenFuel Technol- tists estimate that as little as a 1.8 percent ogies Corporation, in collaboration with Arizona Public Service Company, is recycling reduction in incoming solar radiation carbon dioxide emissions from power plants by using it to grow biofuel stock in the would compensate for a doubling of at- form of—what else?—algae.