Center for Investigative Reporting / By Sarah Terry Cobo

Environmental "externalities," says one expert, "pose a major risk to the global economy and markets are not fully aware of these risks, nor do they know how to deal with them."

Knowing they will face climate legislation sometime in the future, a number of U.S. corporations have already begun to offset their greenhouse gas emissions. The utility giant American Electric and Power isbuying forest projects in Brazil and the disposal company Waste Management isrecovering methane from landfills to use in its trash trucks in California.

But a preliminary report commissioned by theUnited Nations has found that the cost of environmental damages could erase at least one third of the profits major corporations make around the world, if they had to pay for these damages. The study looked at 3,000 of the world's top publicly traded companies, and calculated that their environmental impact amounted to at least $2.2 trillion in 2008. More than half of the damage was caused by greenhouse gas emissions.

The full report, due out this summer and first reported by the Guardian in February, was conducted by the British consultancy firm Trucost, and commissioned by the United Nations Principles for Responsible Investment. Trucost's CEO, Richard Mattison, told the Guardian that industries are facing a completely new paradigm: "Externalities of this scale and nature pose a major risk to the global economy and markets are not fully aware of these risks, nor do they know how to deal with them," he said.