The federal government has given the go-ahead to two major pipelines projects – Trans Mountain and Line 3 – while rejecting Northern Gateway.

In a series of videos, titled "Pipelines, Politics & Indigenous Peoples: Understanding the decisions on Gateway, Line 3 and Trans Mountain", MLI Munk Senior Fellow Ken Coates delves into the long-term implications of pipeline rulings for Canada.

What impact will these pipelines have on the environment?

Watch video number four in the series to find out.

"Pipelines are by far and away the most environmentally-sensitive and safe process", says Coates. He says much of the debate is really about shipping and the marine environment, but he points out that Canada has very safe and effective processes for shipping products such as bitumen.