How to set greenhouse gas emission targets for all countries

Is a credible multilateral climate change agreement feasible? This column says that such global cooperation is necessary and attempts to address the political hurdles. The proposed emissions reduction plan develops formulas to cap atmospheric concentrations of carbon dioxide at 500 ppm while obeying political constraints regarding cost, fairness, and timing. The effects of a changing global climate show up gradually, decade by decade. The effects of a changing US political climate have also been showing up gradually, year by year. A watershed was reached June 25, when the US House of Representatives for the first time approved a bill to limit emissions of greenhouse gases, by a vote of 219 to 212. But the Senate hurdle will be tougher. The attempt to address climate change still has a very long way to go.