The UN Climate Change Report 2007 at a Glance

Average Global Temperatures
According to the UN’s Intergovernmental Panel on Climate Change (IPCC) global average air temperatures rose 0.74 +/- 0.18 degrees Celsius during the past century. Several climate scenarios illustrate how temperatures might increase during the 21st century (Graphic: IPCC). Which of these scenarios becomes reality depends on how much carbon dioxide (CO2) and other greenhouse gases will be emitted. Pre-industrial levels were around 280 CO2 parts per million (ppmv) molecules of dry air; they have since risen to the current level of some 380 ppmv. If global warming is to be limited to 2 degrees Celsius, carbon dioxide concentration has to be stabilized at 400-450 ppmv or less (Graphic: IPCC).