WASHINGTON - The Keystone XL pipeline issue has created a tiff between a former U.S. president and the Canadian government.

The Prime Minister's Office reacted swiftly Wednesday to a letter signed by Nobel laureates, including Jimmy Carter, urging President Barack Obama to reject the pipeline.

Carter is the first former president to come out against Keystone XL.

Prime Minister Stephen Harper's office responded with a warning: Remember 1979.

It was a reference to the dip in oil supply which followed the Iranian revolution and touched off a global panic. Prices spiked and long lines formed at gas stations, helping destabilize Carter's one-term presidency.

"Mr. Carter knows from his time as president during the 1979 energy crisis there are benefits to having access to oil from stable, secure partners like Canada," the PMO said.

The statement also cited multiple reviews by the U.S. State Department, which said the project would create thousands of construction jobs without an impact on the environment.

It was during the 1979 crisis that Carter delivered a memorable televised speech — the so-called "Malaise" address.

He asked Americans to avoid unnecessary trips, use carpools and public transit whenever necessary, follow the speed limit, and lower their thermostats. He called energy conservation "an act of patriotism," one that would help the poorest Americans cope with the price shock.

Ronald Reagan was elected president less than 16 months later.

One environmental economist isn't sold, however, on the comparisons to 1979.

"I think it's a little bit of a stretch to say that KXL would buffer the U.S. against a repeat of the oil crises," said Andrew Leach, a professor at the University of Alberta.

"I don't think our government would want to commit to selling oil to the U.S. at below market prices. We don't have a nationalized oil industry, so suggesting we could co-ordinate, at a national level, selling oil at a discount might raise concerns about energy policies of the 1980s era."

In his famous speech, Carter also stressed the need to become more energy self-reliant — by building pipelines when possible and tapping the nation's abundant shale resources.

The 39th president is now lending his voice to a new crisis: climate change.

The letter from the Nobel winners released Wednesday warned Obama that the pipeline issue is key to his legacy.

"You stand on the brink of making a choice that will define your legacy on one of the greatest challenges humanity has ever faced — climate change," says the letter, also signed by nine other Nobel laureates, including South African archbishop Desmond Tutu.

"As you deliberate the Keystone XL tarsands pipeline, you are poised to make a decision that will signal either a dangerous commitment to the status quo, or bold leadership that will inspire millions counting on you to do the right thing for our shared climate."

Obama has signalled that a decision on the Alberta-to-Texas pipeline will come before summer.

He's being squeezed on the issue by factions in his own party. The president is caught between wealthy anti-Keystone donors and pro-Keystone lawmakers at risk of losing their seats in more conservative areas in this fall's midterm elections.

The stakes in that congressional election could be huge. Nearly half the Supreme Court — four out of nine justices — is older than 75 and the party that controls the Senate might gain the upper hand in reshaping the American judiciary for years to come. High-court nominees must be approved by that chamber.

Until now, other former presidents had expressed support for Keystone XL. George W. Bush told an energy conference in Pittsburgh last year: "Build the damned thing." Bill Clinton has urged people to "embrace" the project, albeit under strict precautions.

In Canada, domestic opponents of the Harper government said the little dig at Carter was typical of an approach to politics. The NDP said it's that tendency to poke environmentalists in the eye, rather than work constructively on climate change, that inflamed opposition to pipelines.

"It doesn't surprise me that they would try to take a run at Jimmy Carter who has, I think, enormous credibility in Canada," said the NDP's Peter Julian.

"Mr. Carter is voicing an opinion that's other than what the Conservatives want him to voice — so their instinct is to try to attack. And this is what they've done about opponents to Keystone, that are growing in the United States. It does not help the cause.

"If the Conservatives feel strongly about Keystone, what they need to do is put in emissions regulations. They need to put in place clear environmental initiatives around oilsands development."

Also on HuffPost:

Loading Slideshow...
  • Photo courtesy <a href="http://www.flickr.com/photos/awksed/11589311265/in/photostream/" target="_blank">Mark O'Henly/Flickr</a>

  • NEXT ----> Some of the most unbelievable pictures from the oilsands

  • Syncrude's Mildred Lake Upgrader, part of The Syncrude Project complex for oil sands processing, is pictured Monday, March 8, 2006 in Fort McMurray, Alberta, Canada.

  • The Syncrude oil sands extraction facility is reflected in a lake reclaimed from an old mine near the town of Fort McMurray in Alberta, Canada on October 22, 2009.

  • A disused mining machine on display in front of the Syncrude oil sands extraction facility near the town of Fort McMurray in Alberta on October 22, 2009.

  • Tailings pond in winter.

  • Syncrude upgrader.

  • Dry tailings.

  • The Suncor oilsands operation uses trucks that are 3 stories tall, weigh one million pounds, and cost 7 million dollars each.

  • Oilsands at night.

  • A tailings pond.

  • Black Cliff in the Alberta oilsands.

  • Oilsands upgrader in winter.

  • Oilsands extraction.

  • Oil sits on the surface at a Suncor Energy Inc. oilsands mining operation near Fort McMurray, Alberta, Canada, on Tuesday, Aug. 13, 2013. Photographer:

  • A large oil refinery along the Athabasca River in Alberta's Oilsands. Fort McMurray, Alberta.

  • Oil mixes with water at a tailings pond at a Suncor Energy Inc. oilsands mining operation near Fort McMurray, Alberta, Canada, on Tuesday, Aug. 13, 2013.

  • Fort McMurray is in the heart of the world's biggest single oil deposit - the Athabasca Oil Sands, and the oil is extracted by surface mining and refined in the region. The oil production is at the heart of the economy.

  • In this Aug. 5, 2005 file photo, the Syncrude upgrader spreads out towards the horizon at the company's oil sands project in Ft. McMurray, Alberta, Canada.

  • This Tuesday, July 10, 2012 aerial photo shows a Nexen oil sands facility near Fort McMurray, Alberta, Canada.

  • This Sept. 19, 2011 aerial photo shows an oilsands facility near Fort McMurray, in Alberta, Canada.

  • This Sept. 19, 2011 aerial photo shows an oilsands tailings pond at a mine facility near Fort McMurray, in Alberta, Canada.

  • This Sept. 19, 2011 aerial photo shows an oilsands tailings pond at a mine facility near Fort McMurray, in Alberta, Canada.

  • The Syncrude extraction facility in the northern Alberta oil sand fields is reflected in the pool of water being recycled for re-use.

  • A night view of the Syncrude oil sands extraction facility near the town of Fort McMurray in Alberta Province, Canada on October 22, 2009.

  • Aerial view of a lake and forests in the vicinity of oil sands extraction facilities near the town of Fort McMurray in Alberta, Canada on October 23, 2009.

  • Workers use heavy machinery in the tailings pond at the Syncrude oil sands extraction facility near the town of Fort McMurray in Alberta , Canada on October 25, 2009.

  • Fort McMurray is in the heart of the world's biggest single oil deposit - the Athabasca Oil Sands, and the oil is extracted by surface mining and refined in the region. The oil production is at the heart of the economy.

  • A large oil refinery in Alberta's Oilsands project. Fort McMurray, Alberta.

  • Next: Alberta Oil Spills

  • CFB Cold Lake, CNRL

    A bitumen leak was reported at a Canadian Natural Resources oilsands operation in the weapons range part of the RCAF base in June 2013.

  • CFB Cold Lake, CNRL

    Company officials said the leak - at what it calls its Primrose operation - was caused by faulty machinery at one of the wells, affected an area of approximately 13.5 hectares and released as much as 3,200 litres of bitumen each day.

  • CFB Cold Lake, CNRL

    Preliminary tallies put the death toll from the leak at 16 birds, seven small mammals and 38 amphibians. Dozen were rescued and taken to an Edmonton centre for rehabilitation.

  • CFB Cold Lake

    As of early August 2013, more than 1.1 million litres of bitumen had been pulled from marshlands, bushes and waterways.

  • CFB Cold Lake, CNRL

    Although CNRL could not say when the leak may finally be stopped, it estimates it will likely cost more than $40 million to clean up.

  • <em>Click through for other recent spill in Alberta</em>

  • Plains Midstream

    Little Buffalo band member Melina Laboucan-Massimo scoops up July 13, 2012 what appears to oil from the pond shoreline near the site of a 4.5 million-litre Plains Midstream pipeline leak detected April 29, 2011. Photos taken at the site and released by Greenpeace of Alberta's second-worst pipeline spill suggest at least part of the site remains heavily contaminated despite company suggestions that the cleanup is complete.

  • Plains Midstream Canada

    A boat passes by a boom stretching out to contain a pipeline leak on the Gleniffer reservoir near Innisfail, Alta., Tuesday, June 12, 2012. Plains Midstream Canada says one of their non-functioning pipelines leaked between 1,000-3,000 barrels of sour crude near Sundre, Alberta, on June 7 and flowed downstream in the Red Deer river to the reservoir.

  • Plains Midstream Canada

    Debris pushes up against a boom as it stretches out to contain a pipeline leak on the Gleniffer reservoir near Innisfail, Alta., Tuesday, June 12, 2012.

  • Plains Midstream Canada

    A boom stretches out to contain a pipeline leak on the Gleniffer reservoir near Innisfail, Alta., Tuesday, June 12, 2012. Plains Midstream Canada says one of their non-functioning pipelines leaked between 1,000-3,000 barrels of sour crude near Sundre, Alberta, on June 7 and flowed downstream in the Red Deer river to the reservoir.

  • Plains Midstream

    A boom stretches out to contain a pipeline leak on the Gleniffer reservoir near Innisfail, Alta., Tuesday, June 12, 2012. Plains Midstream Canada says one of their non-functioning pipelines leaked between 1,000-3,000 barrels of sour crude near Sundre, Alberta, on June 7 and flowed downstream in the Red Deer river to the reservoir.

  • Plains Midstream Canada

    A photographer snaps a boom stretching out to contain a pipeline leak on the Gleniffer reservoir near Innisfail, Alta., Tuesday, June 12, 2012. Plains Midstream Canada says one of their non-functioning pipelines leaked between 1,000-3,000 barrels of sour crude near Sundre, Alberta, on June 7 and flowed downstream in the Red Deer river to the reservoir.

  • Plains Midstream Canada

    A boom stretches out to contain a pipeline leak on the Gleniffer reservoir near Innisfail, Alta., Tuesday, June 12, 2012. Plains Midstream Canada says one of their non-functioning pipelines leaked between 1,000-3,000 barrels of sour crude near Sundre, Alberta, on June 7 and flowed downstream in the Red Deer river to the reservoir.