To be fair, some microbes can help break down specific types of oil over time. But that can be a very slow process: Some oils are easily biodegradable, while others are not. That also doesn't mitigate the immediate devastating effects of an oil spill on the environment.

In other words, oil spilled by pipelines doesn't just "absorb" into the ground. In fact, studies have found that spilled oil can linger for decades.

The Conservatives have been strong supporters of pipeline projects in Canada, notably Keystone XL, which awaits American approval.