WASHINGTON - Nine distinguished recipients of the Nobel Peace Prize have written to President Obama, urging him to reject the proposed Keystone XL tar sands oil pipeline, saying his decision offers "a critical moment" to make good on his pledge to create a clean energy economy.

"We urge you to say no" to the pipeline and "turn your attention back to supporting renewable sources of energy and clean transportation solutions," says the letter (Download PDF), sent today. "This will be your legacy to Americans and the global community: energy that sustains the lives and livelihoods of future generations."  

The letter was signed by nine Nobel Peace Prize laureates: Mairead Maguire and Betty Williams of Ireland, who shared the prize in 1976, Adolfo Pérez Esquivel of Argentina (1980), Archbishop Desmond Tutu of South Africa (1984), His Holiness the Dalai Lama (1989), Rigoberta Menchú Tum of Guatemala (1992), José Ramos-Horta of East Timor (1996), Jody Williams of the United States (1997), and Shirin Ebadi of Iran (2003).

The Keystone XL, proposed by TransCanada Pipelines of Calgary, would carry dirty, toxic and corrosive oil from the tar sands of Alberta through six states in the American heartland to refineries on the Texas Gulf Coast. The Obama Administration has said it will decide by the end of the year whether to permit the pipeline, after the State Department determines whether it is in the national interest.

Opposition to the pipeline has surged in recent weeks as more than 1,250 people were arrested in 14 days of sit-ins at the White House - perhaps the largest wave of civil disobedience ever for an environmental cause in the U.S. More protests are being organized for September 26 in Ottawa and the first week of October in Washington.

"In asking you to make this decision," the Nobel Laureates wrote to Obama, "we recognize the thousands of Americans who risked arrest to protest in front of the White House between August 20th and September 3rd.  These brave individuals have spoken movingly about experiencing the power of nonviolence in that time. They represent millions of people whose lives and livelihoods will be affected by construction and operation of the pipeline in Alberta, Montana, South Dakota, Nebraska, Kansas, Oklahoma and Texas."

The Laureates noted the risk of a pipeline spill contaminating the Ogallala Aquifer, the main source of fresh water for the Great Plains. Concern for the fragile Nebraska Sandhills, which lie above the aquifer, has led Nebraska Gov. Dave Heineman to call for rejection of the pipeline in its current route. TransCanada's existing Keystone I pipeline, which would connect to the XL, has leaked 14 times in its first year of operation.
 
The letter also called attention to tar sands oil as one of the dirtiest energy sources on Earth. If fully developed, the Alberta tar sands would be the second largest source of global warming gases in the world, which the Laureates said "will not only hurt people in the US--but will also endanger the entire planet."

The letter was released today by the Nobel Women's Initiative, an Ottawa-based nonprofit founded in 2003 by six of the only 12 women ever to win the Nobel Peace Prize.

Read the full text of the letter here (.pdf)