Evidence for man-made global warming has reached a “gold standard” level of certainty, adding pressure for cuts in greenhouse gases to limit rising temperatures, scientists said on Monday. “Humanity cannot afford to ignore such clear signals,” the U.S.-led team wrote in the journal Nature Climate Change of satellite measurements of rising temperatures over the past 40 years. They said confidence that human activities were raising the heat at the Earth’s surface had reached a “five-sigma” level, a statistical gauge meaning there is only a one-in-a-million chance that the signal would appear if there was no warming. Such a “gold standard” was applied in 2012, for instance, to confirm the discovery […]