20 Reasons Why Geoengineering may be a Bad Idea
1.Effects on regional climate.
The 1991 eruption of Mount Pinatubo on the Philippine island of 
Luzon, which injected 20 megatons of sulfur dioxide gas into the stratosphere, produced a sulfate aerosol cloud that is said to have caused global cooling for a couple of years. However, researchers at the National Center for Atmospheric Research showed in 2007 that the Pinatubo eruption caused large hydrological responses, including reduced precipitation, soil moisture, and river flow in many regions. Simulations of the climate response to volcanic eruptions have also shown large impacts on regional climate.
2. Continued ocean acidification.
If humans adopted geoengineering as a solution to global warming, with no restriction on continued carbon emissions, the ocean would continue to become more acidic, because about half of all excess carbon dioxide in the atmosphere is removed by ocean uptake. Continued acidification threatens the entire oceanic biological chain.
3. Ozone depletion.
Aerosol particles in the stratosphere serve as surfaces for chemical reactions that destroy ozone in the same way that water and nitric acid aerosols in polar stratospheric clouds produce the seasonal Antarctic ozone hole. For the next four decades or so, additional aerosols from geoengineering would destroy even more ozone and increase damaging ultraviolet flux to Earth’'s surface.
4. Effects on plants.
Sunlight scatters as it passes through stratospheric aerosols, reducing direct solar radiation and increasing diffuse radiation, with important biological consequences. Inserting aerosols or reflective disks into the atmosphere would reduce the total sunlight to reach Earth’'s surface. Scientists need to assess the impacts on crops and natural vegetation of reductions in total, diffuse, and direct solar radiation.
5. More acid deposition.
If sulfate is injected regularly into the stratosphere, no matter where on Earth, acid deposition will increase as the material passes through the troposphere - the atmospheric layer closest to Earth’'s surface. Any additional acid deposition would harm the ecosystem, and it will be important to understand the consequences of exceeding different biological thresholds. Furthermore, more acidic particles in the troposphere would affect public health.
6. Effects of cirrus clouds.
As aerosol particles injected into the stratosphere fall to Earth, they may seed cirrus cloud formations in the troposphere. Cirrus clouds affect Earth’s radiative balance of incoming and outgoing heat, although the amplitude and even direction of the effects are not well understood. While evidence exists that some volcanic aerosols form cirrus clouds, the global effect has not been quantified.
7. Whitening of the sky (but nice sunsets).
Atmospheric aerosols close to the size of the wavelength of light produce a white, cloudy appearance to the sky. They also contribute to colorful sunsets, similar to those that occur after volcanic eruptions. Both the disappearance of blue skies and the appearance of red sunsets could have strong psychological impacts on humanity.
8. Less sun for solar power.
Scientists estimate that as little as a 1.8 percent reduction in incoming solar radiation would compensate for a doubling of atmospheric carbon dioxide. Even this small reduction would significantly affect the radiation available for solar power systems - one of the prime alternate methods of generating clean energy - as the response of different solar power systems to total available sunlight is not linear.
9. Environmental impacts of implementation.
Any system that could inject aerosols into the stratosphere, i.e., commercial jetliners with sulfur mixed into their fuel, 16-inch naval rifles firing 1-ton shells of dust vertically into the air, or hoses suspended from stratospheric balloons, would cause enormous environmental damage. To get the needed trillions of disks into space, engineers would need 20 electromagnetic launchers to fire missiles with stacks of 800,000 disks every five minutes for twenty years. What would be the atmospheric effects of the resulting sound and gravity waves? Who would want to live nearby?
10. Rapid warming if deployment stops.
A technological, societal, or political crisis could halt a project of stratospheric aerosol injection in mid- deployment. Such an abrupt shift would result in rapid climate warming, which would produce much more stress on society and ecosystems than gradual global warming.
11. There’s no going back.
We don’t know how quickly scientists and engineers could shut down a geoengineering system - or stem its effects - in the event of excessive climate cooling from large volcanic eruptions or other causes. Once we put aerosols into the atmosphere, we cannot remove them.
12. Human error.
Complex mechanical systems never work perfectly. Humans can make mistakes in the design, manufacturing, and operation of such systems.
13. Undermining emissions mitigation.
If humans perceive an easy technological fix to global warming that allows for “business as usual,”gathering the national (particularly in the United States and China) and international will to change consumption patterns and energy infrastructure will be even more difficult. This is the oldest and most persistent argument against geoengineering.
14. Cost.
Advocates casually claim that it would not be too expensive to implement geoengineering solutions, but there have been no definitive cost studies, and estimates of large-scale government projects are almost always too low.
15. Commercial control of technology.
Who would end up controlling geoengineering systems? Governments? Private companies holding patents on proprietary technology? And whose benefit would they have at heart? These systems could pose issues analogous to those raised by pharmaceutical companies and energy conglomerates whose products ostensibly serve the public, but who often value shareholder profits over the public good.
16. Military use of the technology.
The United States has a long history of trying to modify weather for military purposes, including inducing rain during the Vietnam War to swamp North Vietnamese supply lines and disrupt antiwar protests by Buddhist monks. Could techniques developed to control global climate forever be limited to peaceful uses?
17. Conflicts with current treaties.
The terms of ENMOD explicitly prohibit “Military or any other hostile use of environmental modification techniques having widespread, long-lasting or severe effects as the means of destruction, damage, or injury to any other State Party.”Any geoengineering scheme that adversely affects regional climate, for example, producing warming or drought, would therefore violate ENMOD.
18. Control of the thermostat.
Even if scientists could predict the behavior and environmental effects of a given geoengineering project, and political leaders could muster the public support and funding to implement it, how would the world agree on the optimal climate? What if Russia wants it a couple of degrees warmer, and India a couple of degrees cooler? Would it be possible to tailor the climate of each region of the planet independently without affecting the others? If we proceed with geoengineering, will we provoke future climate wars?
19. Questions of moral authority.
Ongoing global warming is the result of inadvertent climate modification. Humans emit carbon dioxide and other greenhouse gases to heat and cool their homes and factories. But now that humans are aware of their effect on climate, do they have a moral right to continue emitting greenhouse gases? Similarly, since scientists know that stratospheric aerosol injection, for example, might impact the ecosphere, do humans have a right to plow ahead regardless? So, how should humans judge how much climate control they may try?
20. Unexpected consequences.
Scientists cannot possibly account for all of the complex climate interactions or predict all of the impacts of geoengineering. Climate models are improving, but scientists are discovering that climate is changing more rapidly than they predicted, for example, the surprising and unprecedented extent to which Arctic sea ice melted during the summer of 2007. Scientists may never have enough confidence that their theories will predict how well geoengineering systems can work.
By Alon Robock, MAY/JUNE 2008 BULLETIN OF THE ATOMIC SCIENTISTS.
copyright @ GE1
