There are planetary boundaries that should not be crossed otherwise the Earth's functions tip and go into overdrive, creating inhospitable conditions for humans. This is the conclusion of some of the world's most eminent scientists who gathered for two days at Tallberg in Sweden last week, at which I had the chance to join their deliberation. Indeed, there is evidence tipping has already occurred in the case of global warming arising from the burning of fossil fuels, as the Arctic sea ice is showing signs of melting much faster than expected. ...