There’s an estimated $95 billion global market in carbon trading; profits for some of these companies are doubling, even tripling every year. Europe’s much heralded Emissions Trading System failed to persuade companies, which are the biggest polluters, to reduce their emissions. Instead, emissions are on the rise, and many companies made windfall profits in the first year. The British government is now considering the viability of a personal carbon accounting system. But would Britain's proposed scheme be any more effective at reducing greenhouse gas emissions? Naomi Fowler reports from London.