Under some circumstances, a low altitude smoke cloud would even warm the earth, not cool it. These examples should induce a certain amount of skepticism and make us somewhat more humble about the ability of theory to predict the future of the atmosphere and of climate. But limiting economic growth condemns the poor, especially in the Third World, to continued poverty, if not outright starvation. Substitutes for fossils, such as hydro, geothermal, solar energy, and wind, are all useful in particular applications but not enough to reverse the growth of atmospheric carbon dioxide. In addition, their wide use would require exorbitant capital investments and could be environmentally damaging.
Energy conservation is much to be desired, and there are many unexploited opportunities, to be sure.
But there are also great costs involved if carried too far, as indoor air pollution, including radon, in energy-efficient buildings. Realistically speaking, more conservation can only nibble at the carbon dioxide problem, not solve it. Scientific data from the past tell us that methane has been increasing steadily from sources and for reasons we don't fully understand. There is little point in making extreme efforts to control one set of gases while leaving another untouched. What should concern us most is a very rapid change in climate, one to which our economy cannot adjust.