What would an environmental economist do?
Environmental economists have long argued a carbon price is the best way to factor in the social cost of climate change. Did Obama effectively use a carbon price to nix the Keystone XL pipeline?
Getting out the message: environmental activists seized on the Keystone XL pipeline as a symbol.
Activists can rightfully claim some credit for the Obama's decision to reject the Keystone XL pipeline. How did they do it?
Obama announcing that he has rejected the Keystone XL pipeline – what message does it send on infrastructure?
Climate advocates are cheering rejection of the Keystone XL pipeline, but both our fossil fuel and renewable energy infrastructure badly needs upgrading to tackle climate change.
Road to nowhere?
Obama will decide on the Keystone pipeline before he leaves office, but despite marginal voter interest, it's an issue politicians on all sides will not let die.
Hearing it from supporters: attendee at Clinton rally in New Hampshire expresses opposition to Keystone pipeline.
Hillary Clinton's opposition to construction of the Keystone pipeline has little effect in the short term but reflects building "supply side" strategy of environmentalists to limit fossil fuel development.
Stuck in transit: The Keystone Pipeline proposal has become a symbol for politicians and environmentalists.
Public opinion poll on Keystone pipeline shows more people are concerned with local issues – including the impact of spills on environment and aquifers – than with global warming.