China and whoever are going to poach there if we don't.
I just want to jump in here on this point. As someone who lives in Alberta, we've been talking about Keystone XL vs. Northern Gateway for weeks straight now. The things you should know are:
1) Keystone XL will almost certainly be approved eventually.
Once it detours around certain areas of Nebraska (where the concerns are both environmental, and because Trans-Canada had been treating the landowners incredibly poorly), Obama will almost have to approve it.
He really isn't allowed not to; even this rejection was done because the timeline restriction imposed by Republicans prevents an environmental impact study due to time shortage, rather than the actual merits of the proposal.
I can't say I support it, but it'll happen eventually.
2) Northern Gateway is not going to happen.
They've been trying to build it since the mid-2000s, and it keeps getting delayed.
The first reason is that the line would have to pass through a huge area of native lands in northern BC, and those claims are by no means settled. This means that under Canadian law, just about every BC band can lodge a complaint against the pipeline. Nearly every group is resolutely opposed to the pipeline. Good luck settling that mess.
The second reason is that nobody in western Canada (outside of the oil companies) wants to see large oil tankers sailing around off the Haida Gwaii (aka. the Queen Charlotte Islands). The waters are incredibly treacherous, and there's been an unofficial moratorium on tanker traffic there since the 70's. The memory of the Exxon Valdez is very strong there.
The third reason is that Enbridge is perceived as being bad at building pipelines. I can't speak about that in a professional sense, but they've had a number of major pipeline failures in the last two years.
And if anyone wants to see how likely pipeline failures are, check out
this handy list.