Geoengineering is defined as a “deliberate, large-scale manipulation of the Earth’s environment designed to offset some of the harmful consequences of greenhouse gas-induced climate change” (“Solar Radiation Management” 378). I chose to examine the two main methods of geoengineering, solar radiation management and carbon dioxide removal, to get a better understanding of the role that geoengineering could play in addressing climate change.
The idea of solar radiation management is to increase Earth’s reflectivity to deflect some of the heat that would otherwise be absorbed by the atmosphere. The idea is that by reducing the amount of solar radiation that reaches the atmosphere, the warming effect from greenhouse gases will be offset (“Solar Radiation Management” 378).
One of the options for increasing the reflectivity of Earth is launching reflective surfaces into Earth’s orbit. These space reflectors block a portion of light from reaching Earth, which reduces the amount of warming of the atmosphere. However, a large amount of reflective surfaces would be required; it is estimated that 4,000 square miles of space reflectors would have to be launched every year to effectively reduce warming (“Solar Radiation Management” 380-381). The process of launching and maintaining the massive amount of reflectors required brings into question the feasibility of this option (“Solar Radiation Management” 381).
Another solar radiation management strategy is injecting particles into the atmosphere that would increase the atmosphere’s reflectivity. The theory behind this idea lies in the cooling trends after volcanic eruptions, which naturally release sulfate particles into the environment. For example, after Mount Pinatubo erupted in the Philippines in June 1991, global temperatures cooled by 0.9 degrees Fahrenheit. This geoengineering technique looks to simulate this cooling effect by injecting into the air sulfate aerosols or other particles that would reflect some of the sun’s heat away from the atmosphere (“Solar Radiation Management” 381). There is the potential for small amounts of particles, when properly placed, to have a large impact on the absorption of the atmosphere. It is estimated that injecting 1 kg of sulfur in the right places in the atmosphere could offset the effects of several hundred thousand kilograms of carbon dioxide (Victor, Morgan, Apt, Steinbruner, & Ricke 68). However, there is also the potential for this interference with the atmosphere to have unintended consequences. For example, in addition to cooling effects, the Mount Pinatubo eruption also disrupted the natural water cycle. Rainfall in places throughout the world decreased in the months following the eruption, and it is unknown what effects human injections of these particles would have on rainfall patterns and the greater water cycle (Victor, Morgan, Apt, Steinbruner, & Ricke 70). Another method, known as albedo enhancement, would reduce the amount of heat that is trapped by the atmosphere by making clouds more reflective. It is predicted that increasing the reflectivity, or albedo, of clouds by even 1% could offset the warming effects from doubling the amount of carbon dioxide in the atmosphere (Victor, Morgan, Apt, Steinbruner, & Ricke 67).
Albedo enhancement could also involve increasing the reflectivity of objects on the surface of Earth. For example, roofs could be whitened in order to increase their reflectivity (“Solar Radiation Management” 382). Additionally, darker forests could be replaced with lighter grasslands to increase the reflectivity of some of Earth’s surfaces (Victor, Morgan, Apt, Steinbruner, & Ricke 68).
There are many shortcomings and risks of solar radiation management. In class, we discussed how solar radiation management acts to cover up the effects of human-caused greenhouse gas emissions, and fails to actually address the cause of the problem, which are the high levels of carbon dioxide in the atmosphere. One of the main consequences of allowing high concentrations of carbon dioxide to remain in the atmosphere is ocean acidification. Ocean acidification results from high levels of carbon dioxide being absorbed by the ocean, and has adversely affects both marine and terrestrial ecosystems. One of the main concerns of ocean acidification is coral bleaching, which threatens the large number of species that rely on coral reef ecosystems for survival.
Another concern discussed in class was the irreversibility of many of the solar radiation management strategies. The consequences of many of these projects are unknown, but even less is known about what would happen to the atmosphere and global temperatures if these strategies were stopped. There is the possibility for excessive warming to result from halted efforts of cooling (“Solar Radiation Management” 383). Therefore, despite the potential for immediate relief from global warming, solar radiation management could also have many unknown consequences due to humans’ increased intervention in the natural systems and processes on Earth.
The other type of geoengineering that I focused on was carbon dioxide removal. Instead of addressing the effects of increased carbon dioxide concentrations in the atmosphere, carbon dioxide removal looks to mitigate these effects by actually reducing the amount of CO2 in the atmosphere (Klusinske).
One method of carbon dioxide removal is afforestation and reforestation. Reforestation is defined as the regrowth of forest that was recently deforested, while afforestation is the regrowth of forest that had been deforested for at least 50 years (Klusinske). Trees are an important element in the reduction of atmospheric carbon dioxide since photosynthesis requires the uptake of carbon dioxide.
In class, we discussed the different potentials for the carbon uptake by trees depending on the trees’ age and the climate they grow in. Growing trees uptake the most carbon dioxide, and as trees age, the amount of carbon dioxide that they are able to uptake decreases. Trees are also more efficient at uptaking carbon dioxide in warmer and wetter climates, where trees can grow the fastest.
Ironically, current effects of increased atmospheric carbon dioxide actually benefit plant growth. The more carbon dioxide there is in the atmosphere, the more efficiently trees can uptake CO2 for photosynthesis and growth. Also, the increase in global temperatures that results from greater amounts of carbon dioxide in the atmosphere promote better growing environments for trees. It was pointed out in class, though, that there is only a certain limit to which increased carbon dioxide emissions can be offset by the increased tree growth that it causes (Klusinske).
In class, we also discussed the potential for trees to begin acting as a carbon source rather than a carbon sink if the rate of decomposition is too high. Decomposition of dead plant matter releases carbon to the atmosphere, so events that would cause an increased amount of decomposition, such as extreme weather or disease, would increase atmospheric CO2 concentrations (“Assessment of Possible Carbon Dioxide Removal” 40). However, with many growing forests, afforestation and reforestation could result in the removal of 1 gigaton of CO2 per year (Klusinske).
Carbon dioxide could also be removed from land management practices. Plowing fields before planting crops speeds up the decomposition in the soil, which releases carbon into the atmosphere, so changing this practice would reduce the amount of carbon dioxide released to the atmosphere. Additionally, changing the crops that are planted could affect atmospheric carbon dioxide concentrations. Cover crops are crops that are not planted for the market, but for the purpose of increasing the organic matter in the soil and improving soil quality, which help to reduce the amount of CO2 that is released to the atmosphere. Additionally, planting a variety of crops helps to keep carbon sequestered in the soil (Klusinske).
Another method of carbon sequestration is biochar. Biochar is a type of charcoal that can be produced by burning biomass, such as trees or crop residuals, in a certain way called pyrolysis. By burning these biomasses in this way, the eventual release of carbon to the atmosphere is prolonged significantly. Carbon would be released when the biomass decomposes, but converting it to charcoal, a much more stable form of carbon, slows down the release of carbon dioxide to the atmosphere (“Assessment of Possible Carbon Dioxide Removal” 45). Biochar is not technically considered a carbon dioxide removal technique, though, since it only reduces the release of CO2 to the atmosphere rather than actually remove current amounts.
Accelerated weathering was another carbon dioxide removal strategy discussed in class. Natural weathering removes carbon dioxide from the atmosphere when minerals and rocks become more exposed and are more readily able to react with carbon dioxide (Klusinske). The idea is for the CO2 in the atmosphere to become dissolved bicarbonate ions in the ocean, which will become carbonate sediments that remain on the ocean floor (“Assessment of Possible Carbon Dioxide Removal” 46).
Other ideas include ocean iron fertilization, which involves using iron to increase the growth of phytoplankton and other photosynthesizing organisms to increase the amount of carbon dioxide that is removed during photosynthesis (Klusinske).
Direct air capture and sequestration would follow a similar process to a scrubber in a smokestack, in that it would directly remove carbon dioxide from the surrounding air. Instead of just removing CO2 from a smokestack, though, this geoengineering technique would involve removing CO2 from the surrounding atmosphere (Klusinske).
Another idea is geological sequestration, which would take CO2 from the atmosphere and pump it underground into depleted oil and gas reservoirs, where there is the capacity for large amounts of CO2 to be stored. This process is comparable to reverse fracking, and the concerns of fracking, such as a over-pressurization and leakage, were brought up in class.
A final idea discussed in class was ocean alkalinity enhancement, which addresses the issue of ocean acidification by adding more basic material to the ocean to have a neutralizing effect. For example, limestone could be ground up and added to the ocean to reduce the acidity caused by large amounts of CO2 absorbed in the ocean.
One of the major issues with geoengineering is that we do not know the consequences of starting or eventually stopping many of these projects. One of the points raised during the class discussion was which is a bigger burden to future generations, the responsibility of having to continue geoengineering projects that previous generations started or having to deal with the high amount of CO2 in the atmosphere from previous generations’ habits?
Answering this question also involves debating the role that humans should have in controlling and altering their environment. Up until now, human intervention trends have simulated the beginning of a Kuznets curve with regards to its damage to the environment. One view is that human intervention will follow the path of the Kuznets curve, and there is a point of human intervention where environmental damage will begin to decrease. Another view is that human intervention in the environment has led to negative effects in the past, so further intervention will only continue to hurt the environment; instead of following the downward trend after the peak environmental damage from the Kuznets curve, this view predicts that the environmental damage from human intervention will keep increasing. In class, the point was raised that a lack of human intervention is not possible, though. We can either intervene in the form of geoengineering, or continue emitting carbon dioxide to the atmosphere. Therefore, it is insignificant to debate on whether or not more human intervention will harm the environment, since stopping human intervention is not actually an option.
Another source of controversy involving geoengineering is whether or not focusing on removing existing carbon dioxide will take away from efforts to reduce human emissions. Geoengineering does not actually address the real root of the problem, which is that human habits are putting unsustainable amounts of carbon dioxide in the atmosphere. Therefore, the existence of a problem will continue if humans do not change their own habits.
During class discussion, it was pointed out, though, that humans will be less likely to want to change their habits to the extent required. It would require 60-80% reduction in human-caused greenhouse gas emissions to just keep global warming to its current rate (Victor, Morgan, Apt, Steinbruner, & Ricke 65). Proponents of geoengineering also argue that efforts up until this point have not effectively been able to reduce carbon emissions. In fact, CO2 concentration has increased by an average of 1.76 ppm since 1979, and the rate of increase is rising. In the 1980s and 1990s, the average increase in CO2 concentration was 1.5 ppm, but from 2011-2016, the increase has averaged 2.5 ppm each year (Berwyn). Therefore, humans have proven unable so far to reverse the trend of increasing CO2 emissions, let alone reduce emissions by the amount required for reversal of the damage that has and is still being done.
One idea proposed during discussion to cause real reductions in carbon emissions was a carbon tax. This brings up the issue of regulation and responsibility for human intervention in the environment. As of right now, it is hard to visualize a world in which private organizations and individuals voluntarily charge themselves for their carbon emissions. This role may fall to the government, but especially with the newly elected Trump administration, the implementation of a carbon tax still seems far in the future.
The government’s role in regulation of the environment is another issue of geoengineering. Right now, there is no governing body that controls any individuals or organizations from launching their own sulfates into the atmosphere or building their own devices to start sucking up CO2 from the atmosphere. Now that the idea is out there, it is becoming dangerous to not have some type of regulation on individuals or organizations from taking matters into their own hands. Even the actions of one government or nation could have potentially devastating effects on other parts of the world (“Solar Radiation Management” 383). Therefore, if geoengineering were to be further pursued, it would require a large oversight authority to ensure the protection of all parts of the world.
Overall, the sense from the discussion was that something must be done about the increasing amounts of carbon dioxide in the atmosphere. Although it might be ideal to combat climate change by reducing anthropogenic emissions, current trends suggest that this is not realistic. Geoengineering provides solutions that could immediately and effectively address the mounting concentration of carbon dioxide in the atmosphere. Although increased human intervention and experimentation with a fragile system has its risks, humans have “already engaged in a dangerous geophysical experiment by adding so much carbon dioxide to the atmosphere” (Victor, Morgan, Apt, Steinbruner, & Ricke 76). Therefore, geoengineering could provide the only solution to the environmental damage that human activity has and will continuing having on the Earth.
Berwyn, Bob. “Far From Turning a Corner, Global CO2 Emissions Still Accelerating.” Inside Climate News. N.p., 19 May 2016. Web. 10 Nov. 2016. https://insideclimatenews.org/news/19052016/global-co2-emissions-still-accelerating-noaa-greenhouse-gas-index
Klusinske, Elizabeth. “Geoengineering to Combat Climate Change: Carbon Dioxide Removal.” Decoded Science. Decoded Science, 28 Apr. 2015. Web. 8 Nov. 2016. http://www.decodedscience.org/geoengineering-combat-climate-change-carbon-dioxide-removal/53960
National Research Council of the National Academies. “Chapter Fifteen: Solar Radiation Management.” Advancing the Science of Climate Change. Washington, D.C.: National Academies, 2010. 377-88. NAP OpenBook. Web. 8 Nov. 2016. https://www.nap.edu/read/12782/chapter/19#382
National Research Council of the National Academies. “Chapter Three: Assessment of Possible Carbon Dioxide Removal and Long-Term Sequestration Systems.” Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration. Washington, D.C.: National Academies, 2015. 39-96. NAP OpenBook. Web. 9 Nov. 2016. https://www.nap.edu/read/18805/chapter/5#95
Victor, David G., M. Granger Morgan, Jay Apt, John Steinbruner, and Katharine Ricke. “The Geoengineering Option: A Last Resort Against Global Warming?” Foreign Affairs 88.2 (2009): 64-76. JSTOR. Web. 8 Nov. 2016.