In a notable first, some 215 of the world’s top climate scientists from over 25 countries have signed a declaration directed at the leaders attending the United Nations climate conference in Bali, Indonesia, urging strong action against climate change. In a relatively toned-down document, the scientists said in their own way that climate change really, truly is an amazingly huge problem, so policymakers of the world, it’s time to do something about it already! “The amount of carbon dioxide in our atmosphere now far exceeds the natural range of the past 650,000 years, and it is rising very quickly due to human activity,” the declaration says. “If this trend is not halted soon, many millions of people will be at risk from extreme events such as heat waves, drought, floods, and storms, our coasts and cities will be threatened by rising sea levels, and many ecosystems, plants, and animal species will be in serious danger of extinction.” The signers also say that world greenhouse-gas emissions “need to be reduced by at least 50 percent below their 1990 levels by the year 2050 … there is no time to lose.”