The proposed Keystone XL pipeline would carry tar sands oil from Alberta to refineries on the Gulf Coast. Creative Commons: Contando Estrelas, 2009.

The proposed Keystone XL pipeline would carry tar sands oil from Alberta to refineries on the US Gulf Coast. Creative Commons: Contando Estrelas, 2009.

The proposed Keystone XL pipeline could produce four times the global warming pollution than previously estimated by the State Department, according to a new study on the issue.
The report, published in the scientific journal Nature Climate Change and authored by scientists from the Stockholm Environmental Institute, examined the pipeline’s impact on the global energy market and then connected that impact to the planet’s changing climate.
According to the study, the State Department failed to consider whether demand for Canadian tar sands oil would increase if the pipeline is approved and built. The new analysis found that “for every barrel of increased production, global oil consumption would increase 0.6 barrels owing to the incremental decrease in global oil prices.” Lower prices would be a boon to consumers in the short turn, but in the long term could spell serious trouble for the planet
In an email to the Associated Press, Wesleyan University environmental economist Gary Yohe said:

Lower fuel prices are bad if they don’t include all of the social costs. Consumers are happy, but the planet is not necessarily.

The new study found that Keystone could pour as much as 110 million tons of carbon dioxide equivalent into the atmosphere each year—as much as the tailpipe emissions of 23.1 million cars.
This number is roughly four times greater than the upper limit estimate provided by the State Department, which found that building the pipeline would result in anywhere from 1 million to 27 million tons of carbon dioxide being released into the atmosphere each year.
In addition to the risk Keystone XL poses to groundwater supplies—including the critical Ogallala Aquifer—opponents of the pipeline have repeatedly pointed to the pipeline’s climate impact as a reason to reject it.
Alberta’s tar sands is both the largest and dirtiest industrial project in the world, producing three to five times as much CO2 per barrel as conventional oil. Former NASA scientist James Hansen has called any development of the tar sands to be “game over for the planet,” while one of the authors of this latest report explains that building the KXL would negate climate progress in other areas.
Tar sands are considered to be responsible for a higher proportion of carbon emissions than other sources of oil, given the need for intense industrial processing during extraction and production. One study found that the oil sands produce 23% more greenhouse gases than conventional crude oil.
In spite of the industry’s threats to the climate, it is rapidly expanding. Production of oil in Alberta alone is expected to triple from 1.5 to 4.5 million barrels a day by 2035, potentially adding 706 million tons of CO2 to global emissions annually.
Fossil fuel interests, such as the American Petroleum Institute, argue that halting Keystone XL will not stop tar sands oil extraction, because the oil will just be transported by rail. On the other hand, environmentalists claim that rejecting the massive pipeline would slow production growth, a claim that has been backed up by the International Energy Agency.