Evidence suggests that the Earth’s atmosphere is warming owing to increases in human-made emissions
of greenhouse gases (GHG), primarily carbon dioxide (CO2). Atmospheric CO2 concentrations have increased
by almost 100 ppm (parts per million) since their pre industrial level, reaching 379 ppm in 2005.1 (IPCC, 2007).
Global mean temperatures have risen by 0.74ºC over the past century, with 0.4ºC of this increase occurring since the 1970s.