Climate reality: Voluntary efforts not enough

Upon announcement of the deal, a team of experts led by an MIT professor made quick calculatons: The average global temperature is likely to rise 3.2 degrees Celsius (5.7 degrees F.) above current temperatures.

So the response from many, but not all, environmental activists and poorer nations was "not enough."

That's not for lack of trying.

The U.S. private sector already has invested hundreds of billions of dollars to cut emissions, and that is probably just the beginning no matter what happened in Copenhagen.

Between 2007 and 2008, energy-related carbon dioxide emissions in the U.S. fell 2.8 percent, though part of that was related to the recession.

A study this year by McGraw Hill Construction said between $36 billion and $49 billion of eco-friendly buildings are under development. That figure is expected to triple by 2013.

The owners of New York's Empire State building spent $13.2 million on environmental retrofits to draw new tenants.

Wal-Mart Stores Inc. retrofitted about 500 buildings this year. Part of the project included installing skylights with the goal of cutting up to 75 percent of the energy used to light stores.

In Chicago, a company started a voluntary commodities market to trade credits for reducing carbon pollution. It has reduced carbon dioxide pollution by the equivalent of 400 million metric tons in the six years since 2003. That sounds like a lot, but the U.S. emitted 7.05 billion metric tons of carbon dioxide equivalent last year alone.