The United States can't keep burning natural gas indefinitely if we want to make truly deep cuts in emissions. At some point, the nation will have to transition to cleaner energy if we want to avoid significant climate change...Say the world instead decides to risk more global warming and aims for a carbon target of 550 parts per million. This would pose a very strong chance of breaching the 2?C threshold. Still, natural gas would be useful as an intermediate bridge in this scenario, with global gas use peaking somewhere between 2020 and 2060."Brad Plumer in The Washington Post.