The perspective of pipeline apologists is contrary to the laws of physics and basic economics, neither of which gives a damn about politics. Here are a few points the State Department ought to reconsider:

Nothing to see here. The draft review suggests the climate impacts of the pipeline are limited because the project will not substantially “induce growth in the rate of extraction in the oil sands.” This narrow analysis misses the mark. Researchers now say that the Alberta tar sands contain 360 to 510 billion tons of carbon — more than double that of all oil burned in human history. While only a fraction is considered economically recoverable right now, we humans are genius at finding new and better ways to dig junk out of the ground. Digging begets more digging. Once the big spigot is open, TransCanada will have every incentive to milk the massive tar sands basin for all it is worth.

It’s out of our hands. The idea that the tar sands would get developed at the same rate without the pipeline is undercut by mainstream financial analysis and industry documents that show Keystone XL is the linchpin for tar sands expansion in the next decade. Tar sands may get to market without it, but at a slower rate and a much greater cost. For example, Canadian research and investment advisory firm Peters & Co. says moving tar sands by rail would spike costs twofold, from $7 to $11 a barrel to $15 to $20 a barrel.