Effect

Take aside the obvious complication of acid rain, pumping sulfur dioxide onto the atmosphere - with an aim to reduce solar radiation on earth - would be a courageous (according to the definition of Humphrey Appleby) strategy.

The reasoning is simple: Despite the extensive use of fossil fuel, almost all human food comes from solar energy - directly or indirectly. Wheat and vegetables do photosynthesis; livestock and fish feed on grass and algae and so forth.

The sobering truth is, in terms of energy conversion, photosynthesis is terribly inefficient (only 3 to 6%). Reduction in solar radiation, therefore, would inevitably result in a corresponding drop in food production.

Alas, it means that the world is cooler and food is more scarce. Thank you very much.

The story of volcano Krakatoa told us that much.

PS. The next inevitable environment problem of a cooler world with less food is the increase in utilization of fossil fuel (or nuclear energy, if our fans of environment protection prefer), which increases the amount of carbon dioxide release and cancels out the effect of sulfur dioxide.