How's this for an idea? Not good for astronomy? "Scientists have previously estimated that reflecting less than 1 per cent of sunlight back into space could compensate for the warming generated by all greenhouse gases emitted since the industrial revolution. Possible techniques include putting a giant screen into orbit, thousands of tiny, shiny balloons, or microscopic sulfate droplets pumped into the high atmosphere to mimic the cooling effects of a volcanic eruption. The IPCC draft said such ideas were ;"speculative, uncosted and with potential unknown side-effects""
http://www.smh.com.au/news/environme...919213362.html