Blue and Green: Global carbon dioxide concentrations have surpassed 400 parts per million (ppm) for the first month since measurements began, the latest results from the National Oceanic and Atmospheric Administration (NOAA) show. Scientists have said the record is a significant climate milestone.
According to the UN Intergovernmental Panel on Climate Change, the concentration of all greenhouse gases, including methane and other gasses that are not included in NOAAs measurement, must not exceed 450ppm this century...