Ten climate scientists urged Secretary of State Hillary Rodham Clinton yesterday to consider climate change as part of the environmental review of the northern segment of the Keystone XL pipeline.

The scientists released a letter stating that omission of climate change in the review process for the TransCanada project would be "neither wise nor credible."

"The vast volumes of carbon in the tar sands ensure that they will play an important role in whether or not climate change gets out of hand; understanding the role this largescale new pipeline will play in that process is clearly crucial," the scientists wrote. The signers included a broad representation of climate researchers, including Ken Caldeira, a scientist at Stanford University, and Michael Mann, a Pennsylvania State University climatologist.

In a Federal Register notice in June, the department outlined 11 general topics, such as "cultural resources" and "air quality and noise," that it would consider as part of the pipeline's impacts, but climate change was not among them.

The State Department is currently accepting recommendations via a "public scoping period" through July 30 on additional issues that could inform its environmental analysis.

The pipeline under State Department review is now a diminished version of its original proposal -- it would stretch 1,179 miles from Canada to Steele City, Neb. TransCanada also is aiming to construct a southern segment of the pipeline, the Gulf Coast Project, that does not require overview from State.

In a 2011 review of the original, much longer pipeline, the State Department concluded that production of oil from the oil sands was more carbon-intensive than production of other oils. At the same time, it said that that those extra emissions essentially were irrelevant, since the oil in Canada would be extracted regardless of whether Keystone XL was built.

"Thus from a global perspective, the project is not likely to result in incremental greenhouse gas emissions," State wrote then.

Canadian opposition to alternatives

But environmentalists vigorously oppose State's argument, noting extensive opposition in Canada to other proposed pipelines outside of Keystone XL.

One noted yesterday, for example, that British Columbia Premier Christy Clark has been outspoken in the past week about Enbridge's proposed Northern Gateway pipeline, which would provide an oil conduit to China if built. Clark has said the province intends to press Enbridge extensively as an intervenor at national hearings on the project in the wake of this month's U.S. National Transportation Safety Board report critical of Enbridge's 2010 oil spill in Kalamazoo, Mich. There also is Canadian environmental opposition to a TransMountain pipeline that would run to Canada's west and another Enbridge proposal that would run eastward.

Meanwhile, Nebraska regulators also released a "feedback" report yesterday compiling issues discussed at public hearings on the proposed reroute of the northern segment of Keystone XL around Nebraska's Sand Hills.

The Nebraska Department of Environmental Quality said Nebraskans expressed concerns about climate change at public hearings. However, the Nebraska department said that "the questions about tar sands, the end use of the oil and the future use of the pipeline are beyond the scope of NDEQ's authority and legislative charge."

The other scientists signing the letter were University of St. Thomas professor John Abraham, NASA's James Hansen, Michael MacCracken of the Climate Institute, Harvard University professor James McCarthy, Princeton University professor Michael Oppenheimer, University of Chicago professor Raymond Pierrehumbert, Richard Somerville of the Scripps Institution of Oceanography and George Woodwell of the Woods Hole Research Center.