Stephen Colbert riffed on the latest environmental analysis of the proposed Keystone XL pipeline that came out last week, and President Obama's ongoing pressure to make a decision.

Colbert questions the notion that Alberta's tar sands oil will make it to market whether the 830,000-barrel-a-day pipeline is built or not. Environmentalists are urging the president to stand by his promises to only approve the pipeline if there's no significant environmental impact in doing so.

"The president's own study said the environmental impact is negligible because '...most of Alberta's oil will likely find a way to get to the market anyway -- if not by pipeline, then by rail.' It's inevitable, and if something is inevitable, than America should be the one to do it.

"Case in point, isn't it inevitable that climate change is going to melt the ice caps, so I say we drown the polar bears in the San Diego Zoo."

Take a look at the clip above.