Is "geoengineering" a solution to global warming a good idea? What effect would reflecting sunlight to cool Earth have on ecosystems? Solar Radiation Modification is a type of proposed climate intervention ("geoengineering"), and one method is stratospheric aerosol intervention. This is basically injecting sulfate aerosols into the stratosphere to make the atmosphere more reflective to sunlight so that there is less heat, even for the same amount of greenhouse gasses.
This is essentially mimicking the effect of a big volcano. Climate scientists have been studying this proposal in their models -- international governance issues aside (think about it) -- what effect would it have on the climate system? Yes the planet would cool, but where and how much, and what about rainfall? What about the Indian Monsoon? Everything is connected in the climate system.
Early on this was perceived as an 'alternative' to cutting greenhouse gas emissions, letting us off the hook for continuing to burn coal, and environmentalists resisted. Recently it has been considered as a back-up, supplemental to drastically cutting emissions, one that may be necessary because of the 'warming debt' in the atmosphere from carbon dioxide we already added.
But, ecologists have only recently become aware of this issue and there are huge implications for the biosphere. So, you cool temperature but carbon dioxide concentration remains high in the atmosphere. How does this affect photosynthesis globally? How would it affect global agriculture and fisheries? And cooler is better but it does not solve ocean acidification, so it does not save the coral reefs. And would it cool things enough where ecosystems really need it (the arctic)? A group of us just published a paper available for download below where we urged that ecologists and climate scientists need to work together to consider the ecological consequences and feedbacks. You can read more about the article in a UCR Earth Day news post, as well as a press release from Michigan State University and and article in Popular Science. There was also a radio interview on Canadian Broadcasting Corporation's science show, Quirks and Quarks.