By Seth Borenstein
WASHINGTON -- The much-debated Keystone XL pipeline could produce four times more global warming pollution than the State Department calculated earlier this year, a new study concludes.
The U.S. estimates didn't take into account that the added oil from the pipeline would drop prices by about $3 a barrel, spurring consumption that would create more pollution, the researchers said.
Outside experts not connected to the study gave it mixed reviews. The American Petroleum Institute found the study to be irrelevant because regardless of the pipeline, the tar sands will be developed and oil will be shipped by railroad if not by pipeline, spokeswoman Sabrina Fang said.
The researchers estimate that the proposed pipeline, which would carry oil from tar sands in western Canada to refineries on the Texas Gulf Coast, would increase world greenhouse gas emissions by as much as 121 million tons of carbon dioxide a year.
The department said this year that at most, the pipeline would increase world carbon dioxide emissions by 30 million tons.
Such emissions have been on the mind of President Barack Obama, who has said his administration would allow the pipeline to be built "only if this project does not significantly exacerbate the problem of carbon pollution."
The new estimates, from scientists at the Stockholm Environment Institute, were published Sunday by the journal Nature Climate Change. Peter Erickson, lead author, said his work implies that the pipeline could basically wipe out reductions from some potential pollution-cutting policies under discussion.