Nov. 2 (Bloomberg) -- The recession and technological advancements will drive down U.S. carbon dioxide emissions even without passage of legislation to reduce greenhouse gases, a study says.

The report by New Energy Finance, a London-based carbon markets researcher, concludes that carbon emissions will drop 3.1 percent by 2020 without new government intervention.

That reduction would represent a historic shift from continual increases, even though it is not enough to solve global warming, the report said.

“It’s clear that the longstanding trend of emissions rising year after year virtually automatically has been broken,” said Milo Sjardin, head of U.S. carbon markets at New Energy Finance in a statement. “The question now is whether policymakers can accelerate that trend sufficiently to address the threat of a warming planet.”

Senate legislation would cut emissions from covered facilities 20 percent by 2020, by curbing carbon dioxide emissions and creation of a market to let companies buy and sell pollution credits.

The report found that under the bill, companies will cut U.S. emissions 7.1 percent by 2020, including factory reductions and so-called offsets, which are pollution control projects paid for by polluters. The rest of the covered cuts will come from overseas offsets, banking reductions made before 2020 and borrowing from future limits, the report said.

The report also found that between 2005 and 2009, the U.S. will cut emissions 4.7 percent.

The Senate bill, sponsored by Democratic Senators Barbara Boxer of California, and John Kerry of Massachusetts, is scheduled to be debated by Boxer’s Environment and Public Works Committee tomorrow.

To contact the reporter on this story: Daniel Whitten in Washington at dwhitten2@bloomberg.net

Last Updated: November 2, 2009 14:00 EST