Due to results of scientific studies that have indicated drastic climate changes, a scientific consensus has transpired that acknowledges the adverse consequences of global warming. As a result, methods to mitigate global warming have become widely deliberated. Resnik and Vallero (2011) addressed two basic policy options for responding to global warming and discussed the overall difficulties with climate change mitigation. The authors posed geoengineering as a useful method to combat global warming through carbon dioxide removal and solar radiation management. Two proposals for solar radiation management are assessed, and the advantages and disadvantages of each compared. Objections to geoengineering are then recognized through discussion of pragmatic and ideological critiques. Because other methods to combat global warming have been ineffective thus far, Resnik and Vallero conclude that geoenginnering is a viable proposal. Further research and discussion are needed before geoengineering tactics are implemented, but other methods of mitigation should be undertaken in the meantime. The authors conclude that mitigate both the symptoms and causes of global warming should ultimately be pursued simultaneously. —Michela Isono
The relationship between climate changes and global warming has been the subject of numerous studies that indicated record high surface temperatures and significant increases in sea levels. The emission of greenhouse gases, particularly carbon dioxide (CO2) and methane (CH4), into the atmosphere is correlated with global warming. Greenhouse gases trap heat in the earth’s atmosphere and prevent the earth from cooling. As a result, the earth’s surface temperature increases and polar ice sheets and glaciers melt causing sea levels to increase. Not only will the temperature and sea levels continue to rise, but numerous adverse consequences for human health and the environment will result if methods to lessen the production of human-produced (anthropogenic) greenhouse gases are not implemented.
Resnik and Vallero addressed two current policy options to counter global warming: mitigation and adaptation. The authors defined mitigation as a method to inhibit and repress climate change, and adaptation as a method to prepare for the effects of global warming. They cited efforts such as regulations to control emissions, carbon taxes, market-based incentives, changes in behavior, and control of population growth and development as mitigation techniques, and efforts such as building infrastructure to prepare for natural disasters, developing crops that can grow in a drought, increasing water supplies and improving responses to infectious diseases as adaptation techniques. These efforts proved difficult due to the demands and risks which included: major changes in human behavior and habits, potential adverse economic impacts, strict international cooperation, the responsibility of industrialized nations compared to developing nations, and the political debate surrounding the authenticity of climate change and global warming. Resnik and Vallero considered both options’ efforts ineffective as a result.
The authors then discussed the topic of geoengineering as an alternative method to combat global warming. They defined geoengineering as a method that would utilize technology to purposefully manipulate the planetary environment to mitigate the anthropogenic changes on a global scale. Two methods of geoengineering were cited: CO2 removal and solar radiation management. Carbon dioxide removal removes and stores excess CO2 from the atmosphere. Solar radiation management reflects sunlight by increasing the reflectivity of clouds. The main difference between the two types of geoengineering is that CO2 removal deals with a producer of climate change (the surplus of greenhouse gases in the atmosphere), whereas solar radiation management deals with the symptoms of climate changes that have already occurred.
Resnik and Vallero assessed and compared two proposals for solar radiation management. The first method was introduced by geochemist Paul Crutzen in 2006 and the second method was developed by David W. Keith in 2010. Crutzen’s proposal was developed based on findings from the eruption of Mount Pinatubo volcano in 1991. The eruption caused 10 million metric tons of sulfur dioxide (SO2) to be emitted into the stratosphere. The SO2 then transformed into sulfate particles, which increased cloud-reflecting power (cloud albedo) by reflecting more sunlight into space, and ultimately cooled the planet by 0.5˚C. Crutzen thus proposed that airplanes should spray sulfur dioxide into the stratosphere to increase cloud albedo to cool the planet. Crutzen advocated that SO2 should be sprayed into the stratosphere rather than the troposphere because the particles would have a greater impact on cloud albedo and would last for 1–2 years. He estimated the cost would be $25–$50 billion per year in order to combat climate change; however the cost would be dependent on the amount of emitted greenhouse gases.
Crutzen also acknowledged the potential risks of his proposal. First, SO2 is considered an air pollutant and can lead to respiratory problems that increase the number of emergency department visits and hospitalizations. The Environmental Protection Agency also regulates SO2 in the United States. Second, spraying SO2 could disrupt the ozone chemistry and cause the protective ozone layer to thin. The ozone layer is important because it acts as a protector from harmful ultraviolet light radiation. Third, SO2 transforms into sulfuric acid and becomes acid rain. Acid rain decreases the pH of soil, which is detrimental to ecosystems and plant species. Fourth, spraying sulfur dioxide would cause a higher level of CO2 to remain in the atmosphere. When CO2 dissolves in the ocean, it increases the acidity of the water, which endangers plankton and species with shells, which would impact other marine species and ecosystems. Fifth, increasing cloud albedo could alter rain patterns, wind, storms, and temperature distribution in addition to increasing the amount of diffuse light that hits the earth. This would case the sky to appear whiter and could affect plant photosynthesis and solar power. Lastly, if too much SO2 is sprayed, too much cooling could occur which could initiate an ice age.
The second proposal was developed by Keith as an alternative to Crutzen’s proposal. Keith recommended that circular nanoparticles made up of layers of aluminum oxide, metallic aluminum, and barium titanate, should be dispensed into the stratosphere. The advantage to the nanoparticles was that they would rise above the stratosphere, which would reduce their ability to interfere with the ozone chemistry. This would enable the particles to stay in the atmosphere longer than sulfur dioxide and decrease the need for continual replenishment of the SO2. Additionally, the nanoparticles could be specifically engineered to release the right amount of diffuse light and not produce acid rain.
Keith’s proposal also had risks. First, the proposal had not been tested previously and no natural occurrence like the volcano provided supporting evidence of its potential effects. Second, it could also affect ocean acidification, rain patterns, wind, storms, and temperature distribution. Third, the health and environmental risks of the nanoparticles are not well known. Lastly, the proposal could be extremely expensive, as the exact amount of materials needed to create and perform the task is not entirely known.
Resnik and Vallero next recognized the objections to geoengineering through the discussion of pragmatic and ideological critiques. The authors defined pragmatic critiques to address the practical issues to employing geoengineering solutions, and defined ideological critiques to represent the opinion that geoenginnerring proposals should not be utilized even if practical difficulties were irrelevant. The pragmatic critiques encompassed problems that pertained to environmental and public health issues, monetary costs, and effectiveness. The authors also recognized the difficultly in acquiring and maintaining international cooperation as well as the low level of scientific understanding regarding the impact of many gases. Resnik and Vallero concluded that geoengineering methods should not be implemented unless there is sufficient evidence that assures safety and effectiveness. The authors stated that smaller-scale proposals with lower risks should be tried before larger-scale proposals with greater risks are used.
The addressed ideological critiques stated that geoengineering proposals would take away monetary and intellectual resources from other non-geoengineering methods to mitigate global warming. The authors disagreed with this critique and stated that people in favor of stopping global warming should agree to any technique that is safe, feasible and effective. Another critique stated that geoenginnering methods should not be utilized at all and that environmental policies should revert nature to its natural state. Other opponents argued that geoengineering would favor the industry producers of greenhouse gases and would detract from efforts to reduce greenhouse gases. Lastly, critics opposed the use of technology as a solution to fix climate change. The authors did not agree with the ideological critiques due to the controversial suppositions. They addressed how major benefits could be overlooked if the consequences of not utilizing geoengineering were ignored.
Because other methods to combat global warming have been ineffective thus far, Resnik and Vallero conclude that geoenginnering is a viable proposal. Further research and discussion is needed before geoengineering tactics are implemented, but they believe that other methods of mitigation should be undertaken ardently; both the symptoms and causes of global warming should be addressed and methods to mitigate both the symptoms and causes can and should be pursued simultaneously.