Carbon trading is now the fastest-growing commodities market on earth. Since 2005, when major greenhouse-gas polluters among the Kyoto signatories were issued caps on their emissions and permitted to buy credits to meet those caps, there have been more than $300 billion worth of carbon transactions. Major financial institutions such as Goldman Sachs, Barclays, and Citibank now host carbon-trading desks in London; traders who once speculated on oil and gas are betting on the most insidious side effects of
our fossil fuel