The first thing I ever wrote on global warming was an article pointing out the uncertainties in Global Climate Models. Freeman Dyson, one of the world’s greatest living mathematical physicists, had similar concerns.
The main conclusion of the Nordhaus analysis is that the ambitious proposals, “Stern” and “Gore,” are disastrously expensive, the “low-cost backstop” [Ed: a hypothetical low-cost technology for removing carbon dioxide from the atmosphere, or for producing energy without carbon dioxide emission] is enormously advantageous if it can be achieved, and the other policies including business-as-usual and Kyoto are only moderately worse than the optimal policy. The practical consequence for global-warming policy is that we should pursue the following objectives in order of priority. (1) Avoid the ambitious proposals. (2) Develop the science and technology for a low-cost backstop . (3) Negotiate an international treaty coming as close as possible to the optimal policy, in case the low-cost backstop fails. (4) Avoid an international treaty making the Kyoto Protocol policy permanent. These objectives are valid for economic reasons, independent of the scientific details of global warming.
I’ve often written that my only modification to this is that the “optimal policy” of a global carbon tax is not really optimal because of practical considerations. Dyson in the last sentence of this paragraph makes the point that this is the rational conclusion even in the face of the climate science.
What gets really interesting, however, is when Dyson goes on to discuss what a backstop technology might look like:
The science and technology of genetic engineering are not yet ripe for large-scale use. We do not understand the language of the genome well enough to read and write it fluently. But the science is advancing rapidly, and the technology of reading and writing genomes is advancing even more rapidly. I consider it likely that we shall have “genetically engineered carbon-eating trees” within twenty years, and almost certainly within fifty years.
Carbon-eating trees could convert most of the carbon that they absorb from the atmosphere into some chemically stable form and bury it underground. Or they could convert the carbon into liquid fuels and other useful chemicals. Biotechnology is enormously powerful, capable of burying or transforming any molecule of carbon dioxide that comes into its grasp. Keeling’s wiggles prove that a big fraction of the carbon dioxide in the atmosphere comes within the grasp of biotechnology every decade. If one quarter of the world’s forests were replanted with carbon-eating varieties of the same species, the forests would be preserved as ecological resources and as habitats for wildlife, and the carbon dioxide in the atmosphere would be reduced by half in about fifty years.
We have no idea what technologies will be available to us between now and 2100. Imagine planners in the year 1908 trying to figure out how to set up a system of taxes or rationing to limit emissions over the next century. They would probably focus a lot on the number of horses and rail engines we would need, and probably wouldn’t think a lot about jet aircraft and nuclear power.