IPCC: 30 years to climate calamity if we carry on blowing the cTheir other key findings in the report – the first such assessment since 2007 and only the fifth since 1988 – included: • Atmospheric concentrations of carbon dioxide, methane and nitrous oxide are now at levels “unprecedented in at least the last 800,000 years”. • Global temperatures are likely to rise by 0.3C to 4.8C by the end of the century depending on how much governments control carbon emissions. • Sea levels are expected to rise a further 26-82cm (10-32in) by 2100. The wide variation in part reflects the difficulty scientists still have in predicting sea level rises. • The oceans have acidified, having absorbed about a third of the carbon dioxide emitted.arbon budget | Environment | The Guardian