According to the World Meteorological Organization (WMO), the volume of greenhouse gases in the atmosphere hit a new record in 2011. CO2, the primary anthropogenic greenhouse gas, reached 390.9 parts per million (ppm) in 2011, 40% higher than pre-industrial levels. This value has increased by an average of 2ppm globally over the past decade. The WMO stated that 375 billion tons of carbon has been released into the atmosphere since the industrial era began in 1750, which is likely to linger for centuries and cause further warming. Concentrations of other potent greenhouse gases including methane, nitrous oxide, HCFCs and HFCs are also on the rise.