Canada to renege on its pledges over climate change

Critics have been asking if it is fair that Canada is allowed to withdraw from its promises over reducing emissions.
More here:
Canada withdraws from pledges over climate change

The UK has also come under attack for its support to Canada over the Tar Sands.

The tar sands of Northern Alberta, Canada – also called oil sands – are one of the largest remaining deposits of oil in the world. Developing the tar sands has created the biggest industrial development project, the biggest capital investment project, and the biggest energy project in the world. It has also created a literal hell on earth.
Tar Sands - Greenpeace opinion
Tar Sands - wikipedia

In a time when Oil reserves are getting limited and expensive to extract is the impact of extracting bitumen from the Tar Sands of Canada and Venezuela worth the environmental cost. Or does there need to be stricter controls over the exploitation of this resource?
How is the land being regenerated after extraction?