Comment & Debate
Use of solar shades is a proposed approach to the mitigation of global warming through planetary engineering. By intentionally changing the Earth’s albedo, or reflectivity, scientists propose that we could reflect more heat back out into space, or intercept sunlight before it reaches the Earth through a literal shade built in space. A 0.5% increase in albedo is believed capable of roughly halving the effect of CO2 doubling. The debate regarding solar shading revolves around numerous questions: Is global warming irreversible, making geoengineering a necessary, last-resort? Even if we are able to cut and even eliminate greenhouse gas emissions, what should be done about the greenhouse gases that are still in the atmosphere? Are these quantities of greenhouse gases sufficient to continue the process of global warming? Does this make solar shading a necessary effort to reduce atmospheric greenhouse gases? Is geoengineering generally consistent with environmental ethics? Are any of the environmental risks worth taking if solar shading has a chance of effectively fighting global warming? What are the specific pros and cons of the various approaches to solar shading: space-shield, sulfur dioxide, space ring, and others?
“Global Warming is not caused by greenhouse gases themselves but by the solar energy that they trap on Earth. If we can’t reduce the amount of greenhouse gases present in the atmosphere fast enough, we are faced with a problem. But what if we could influence the other variable: the amount of solar energy that gets to the Earth?”
“A solar shield that reflects some of the Sun’s radiation back into space would cool the climate within a decade and could be a quick-fix solution to climate change, researchers say.”
“Even if all industrial pollution and auto emissions suddenly ceased today, Earth’s climate will warm at least 1 degree by the year 2100 and seas will rise 4 inches (11 centimeters), according to a new study…The warming is likely to continue through 2400, another study forecasts…The worst-case scenario projects the global average temperature rising 6.3 degrees Fahrenheit within this century and the sea level climbing a foot or more…”Many people don’t realize we are committed right now to a significant amount of global warming and sea level rise because of the greenhouse gases we have already put into the atmosphere,” said Gerald Meehl, who led the study out of the National Center for Atmospheric Research (NCAR).”
“Lesser of two evils?…Hansen’s study suggests that only moderate additional warming is likely to trigger the disintegration of the west Antarctic and Arctic ice sheets – events which would be near-impossible to reverse…”If this is the case, then I am not clear on what the ‘greenest’ path is,” says Caldeira. “Is it better to let the Greenland ice sheet collapse and let the polar bears drown their way to extinction, or to spray some sulphur particles in the stratosphere?””
“The sunshade is no substitute for developing renewable energy, the only permanent solution.” In general, only misperceptions can lead to conclusions that sunshades are “replacing” approaches to cutting emissions.
“Dan Lunt of the University of Bristol, UK, and colleagues…found that Earth under a sunshade would not simply revert to its pre-industrial climate. Instead the tropics would be cooler than pre-industrial times by 1.5 °C, while high latitudes would be warmer by 1.5 °C, leading to less sea ice”
“Personally, as a citizen not a scientist, I don’t like geo-engineering because of the high environmental risk. It’s toying with poorly understood complex systems. I think the Earth’s system is so complicated that our interfering with it is very likely to screw things up and very unlikely to improve things. And this is the only planet we have.”[1]
“The knowledge that we maybe could engineer our way out of climate problems inevitably lessens the political will to begin reducing carbon dioxide emissions.”[2]
By reducing the amount of sunlight that enters the atmosphere, solar shading decreasing the amount of energy available to solar energy cells. This is cause for concern because solar energy is a major source of 0-emission power, and so a significant solution to the global warming crisis. To diminish this solution is to weaken the fight against global warming.
“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.”
“the truth is, we’re already performing an unauthorized experiment on our climate by adding billions of tons of man-made carbon dioxide to the atmosphere. Unless the geopolitics of global warming change soon, the Hail Mary pass of geoengineering might become our best shot.”
It is impossible for humans to avoid geoengineering in the future. The earth’s climate has always shifted dramatically throughout its history. The Earth will, for instance, enter another ice age fairly soon. Should we, then, just allow this to happen? No, particularly if it means sacrificing millions of human lives and civilization as we know it. We should make the world work for us, not allow it to obliterate us. And, if we assume geoengineering is enevitable, then there is no moral boundary to doing it now, when global warming poses the threat that does to human civilization.
“We have been trying to pinpoint the one really bad thing that argues against geoengineering the climate. But it is really hard to find.”[3]
“Over the past couple of years, it’s gone from an outsider thing to something that is increasingly discussed.”
“I should say right up front, I am not at all in favour of geoengineering. I think it’s inherently unethical. I don’t see how you decide on the basis of all humanity how to change the planet.”[4]
There are ethical questions of whether we commit children to a planet that requires constant tinkering. “We’d have to keep geoengineering indefinitely to balance out continued greenhouse-gas emissions.”
“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.”
“The reduction in incoming sunlight would be 0.5 to 1%, enough to neatly stop global warming and keep temperatures stable. It would give us time to stabilise our emissions, then start the long process of filtering greenhouse gases back out of the atmosphere and storing them somewhere. The Lens can of course be adjusted, so as greenhouse gas levels dropped the diffusion effect would be reduced as well, until we reached a point where the Lens was no longer required and could be safely dismantled, or more playfully used to frighten the hell out of everyone in a medium-sized nation with an appropriate orbital insertion to enter the Earth’s atmosphere flat-on.”
Solar shading would reduce the amount of sun light that hits the surface of the earth. This would reduce the amount of sunlight that plants can use as energy in the process of photosynthesis, which may damage individual plants and have a negative effect on ecosystems.
Solar shading will reduce the amount of sunlight that hits bodies of water, which will reduce precipitation in some places.
This is related to shifts in the wind patterns and is seen in the aftermath of volcanoes.
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