I just read a great article in Wired about efforts to geoengineer a cooling of the Earth, since it’s clear to most that a complete cessation of carbon dioxide production is not feasible. The proposal is to capture sulfur dioxide from power plants, release it into the upper atmosphere (using jets, balloons, etc) where it will bond with water to form microscopic droplets of sulfuric acid, which will reflect a small portion (1-2%) of the sun’s energy back into space. The earth cools a bit, and within a year or two, the sulfuric acid falls to earth.
The inspiration came from a volcanic eruption in the Philippines in 1991, which created the same effect back then, and temporarily cooled the earth.
Of course, there’s always the possibility of unintended consequences. In fact, proponents admit that the sulfuric acid could (at least temporarily) destroy ozone, and fall to earth as acid rain. I don’t know what the extent (and how long-lasting) these effects are. I also don’t know if the reduction of sun energy would decrease food production, or disrupt the food chain enough to harm ecosystems. The problem is that these questions have incredibly complex scenarios. Mathematical modeling might only capture part of the picture.
One thing is for certain, though: global warming is real, and it will result in substantial changes for many parts of the planet. Doing nothing (or thinking hybrid cars and CO2 reduction treaties will do the trick) is irresponsible thinking. Considering the cost of the sulfur dioxide proposal (about $1 billion per year), we should seriously consider that the solution to global warming, at least in the relative short-term (over the next 10 years or so) might require us to seriously look at geoengineering proposals like this one.