The article looks into how trading pollution permits can help countries meet their emission reduction targets. It starts by examining scenarios from no trading to full global trading of permits. The study finds that when more countries are involved in trading, it benefits both developed and developing countries. Developed nations gain more from expanding the market, while developing countries get money and reduce their carbon emissions. However, the former Soviet Union may not benefit as much. Including China in global trading could make it a top destination for clean projects, but China needs to improve its strategies to realize these benefits. It's important to have clear rules for new countries joining the trading system to avoid conflicts.