Blue sky tinkering (Filed: 17/09/2006)Page 1 of 5 Scientists fighting global warming are now considering wacky ways of deliberately manipulating the environment to control the world's climate. Philip Sherwell in New York reports on the schemes that were once dismissed as the work of crackpots Trillions of tiny sunshades orbiting in space; a mirror 150 miles high stationed between Earth and the sun; clouds sprayed with seawater; planes pumping sulphates into the stratosphere. They may sound to a layman like the weird and wacky fantasies of an eccentric bunch of boffins, but such ambitious plans for cooling the planet are...