On a per capita basis, Britain is responsible for more of the carbon dioxide now in the atmosphere than any other nation on Earth because it has been burning it from the dawn of the Industrial Revolution.
What makes tar sands particularly odious is that the energy you get out in the end, per unit carbon dioxide, is poor. It's equivalent to burning coal in your automobile.
It's as certain that as long as fossil fuels are the cheapest energy, we will just keep burning them.
What has become clear from the science is that we cannot burn all of the fossil fuels without creating a very different planet.
Burning all the fossil fuels will destroy the planet we know, Creation, the planet of stable climate in which civilization developed.