When, on May 10th 2013 scientists at Mauna Loa Observatory on the big island of Hawaii announced that global CO2 emissions had crossed a threshold at 400 parts per million (ppm) for the first time in millions of years, a sense of dread spread around the world and not only among climate scientists. CO2 emissions have been relentlessly climbing since Charles David Keeling first set up his tracking station near the summit of Mauna Loa Observatory in 1958 to monitor average daily global CO2 levels. At that time, CO2 concentrations registered 315ppm. CO2 emissions and atmospheric concentrations have been relentlessly climbing ever since and, as the records show, temperatures rises will follow.