Preliminary and incomplete SHARING THE BURDEN OF SAVING THE PLANET: GLOBAL SOCIAL JUSTICE FOR SUSTAINABLE DEVELOPMENT Lessons from the Theory of Public Finance

(a) Global warming is a global problem and needs to be addressed globally. Unless all countries participate, there is a danger of leakage; reductions in one country may be more than offset by increases elsewhere. (b) Global warming is a long-run problem. We are concerned not so much with the level of emissions in any particular year, as with the long run levels of atmospheric concentrations of greenhouse gases. (c) The costs of reducing the level of emissions (limiting the increases in atmospheric concentration of greenhouse gases) will be much lower if it is done efficiently. Efficiency implies comprehensiveness—we need to address all sources of emissions and explore all ways of reducing atmospheric carbon concentrations, including carbon storage and carbon sequestration. (d) There is considerable uncertainty, both about the level of “tolerable” increases in greenhouse gas concentrations and the impact of particular policy interventions. (e) Global warming is a public good problem, so there is a risk of free riding. This means that there will have to be some system of credible enforcement.