President Obama has finally rejected the Keystone XL pipeline. This comes after the U.S. State Department on Wednesday rejected a request by TransCanada to delay the permit review.

According to Amy Harder of the Wall Street Journal, the president cited “the urgency of climate change, and the need for American leadership on that problem, as key reasons for his decision.” This reasoning begs the question: what effect would Keystone XL have had on climate change?

Much of the criticism levied at Keystone XL comes not from the pipeline itself but the supposed “dirty” oilsands from whence Keystone XL would have transported up to 830,000 barrels a day to refineries in the Gulf Coast. So it’s worth mentioning that in 2012, Canada’s oilsands accounted for only 0.1 per cent of global greenhouse gas emissions.

The small scale of the oilsands greenhouse gas emission impact was best captured by comments from Fatih Birol, now the executive director of the International Energy Agency’s (IEA). In a 2014 interview, he stated that “to be frank, the additional CO2 emissions coming from the oilsands is extremely low.”

Birol would go on to add, in reaction to the IEA’s forecast that oilsands production would increase by more than three million barrels a day over the next 25 years, that “the emissions of this additional production is equal to only 23 hours of emissions of China—not even one day.”

These figures, and the contribution of Canada’s oilsands to global emissions, are likely even smaller, as the New York Times reported this week that China has been burning up to 17 per cent more coal a year than was initially thought. Early estimates indicate that this means China has released about 900 million metric tons more CO2 from 2011 to 2013.

Given how small the oilsands is in the grander scheme of greenhouse gas emissions, we return to the question: what sort of impact would Keystone XL have had on climate change?

In his congressional testimony on Keystone XL, climate scientist Paul “Chip” Knappenberger used the U.S. Environmental Protection Agency (EPA) estimates of the additional emissions that may result if the pipeline gets build to calculate what the impact of the additional emissions would be on the warming of the planet using a climate model that was developed with the support of the EPA.

Using EPA emissions assumptions, Knappenberger calculated that “the average temperature rise works out to less than 0.00001 degree C per year. That is 1/100,000 of a degree.”

In fact, building the pipeline could actually lead to fewer greenhouse gas emissions being released. According to the State Department’s review of the project, depending on the scenario (only rail, rail/pipeline, rail/tanker), transportation alternatives to Keystone XL could increase annual CO2 emissions by 27.8 per cent and 41.8 per cent.

With all due respect to President Obama, using climate change as a reason to reject the pipeline is weak tea, especially if you also consider that the U.S. has built the equivalent of 10 Keystone XL pipelines since 2010.