Guardian: In a nondescript conference centre five years ago, as temperatures fell to freezing outside in the streets of Copenhagen and protesters gathered, world leaders did something remarkable: they put a limit on how high temperatures should be allowed to rise as man-made global warming takes hold.
It was the first time the nearly 200 countries in the UN climate talks process had put a number on what constituted the limit for dangerous climate change (Germany had done it years before, followed by the...