Economic Times: Levels of three key greenhouse gases - carbon dioxide (CO2), methane and nitrous oxide - are the highest in at least 800,000 years, the UN Intergovernmental Panel on Climate Change ( IPCC) said Sunday in the final chapter of a landmark report. From 1880-2012, the global average surface temperature rose by 0.85 degrees Celsius (1.5 degrees Fahrenheit), while the global mean sea level rose by 19 centimetres (7.6 inches) from 1901-2010, it said.