Greenhouse gasses on the rise — Without additional action by governments, emissions of the six main greenhouse gases — carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, PFCs and HFCs — are set to rise dramatically. Between 1970 and 2004, emissions of these gases increased by 70 per cent.
Government intervention can help — By adopting stronger climate change policies, governments could slow and reverse these emission trends and ultimately stabilize the level of greenhouse gases in the atmosphere. For example, stabilizing greenhouse gas levels at 445-490 ppm — the most ambitious target that was assessed — would require global CO2 to peak by 2015 and to fall to 50-85 per cent of 2000 levels by 2050. This could limit global mean temperature increases to 2-2.4°C above pre-industrial levels.
Critical levels — Stabilizing greenhouse gases levels at 535-590 ppm would require global CO2 emissions to peak by 2010-2030 and return to -30 per cent to +5 per cent of 2000 levels by around 2050. This could limit the temperature increase to 2.8-3.2°C. If emissions peak later, more warming can be expected. By way of comparison, the 2005 level of greenhouse gases is about 379 ppm.
Avoiding the worst climate change impacts — Mitigation efforts over the next two to three decades will determine to a large extent the long-term global mean temperature increase and the corresponding climate change impacts that can be avoided. Properly designed climate change policies can be part and parcel of sustainable development and the IPCC’s findings confirm that sustainable development paths can reduce greenhouse gas emissions and reduce vulnerability to climate change.