Climate change targets: 350 ppm and the EU two-degree target

Topics: Climate change ,

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Published: Jun 23, 2008 Last modified: Apr 13, 2011

The 350 ppm CO2 target is the focus of an international campaign announced today in several media by the Tällberg Forum. This is the follow-up to the objective proposed by the NASA Chief Scientist James Hansen and his colleagues to limit the concentration of carbon dioxide in the atmosphere to 350 ppm (parts per million). The goal is to avoid global climate change with potentially very large and irreversible effects on human society and the natural environment.

How does this compare to the EU target to limit the increase in global temperature to a maximum of 2 degrees centigrade over pre-industrial levels?

The Intergovernmental Panel on Climate Change (IPCC), in its 4th Assessment report, has indicated that achieving the 2 ºC target will mean stabilising greenhouse gas (GHG) concentrations in the atmosphere at about 445 to 490 ppm CO₂-equivalents. This includes a number of greenhouse gases (not only carbon dioxide), and corresponds to about 400 ppm CO₂ alone. A stabilisation at 400 ppm CO₂-equivalents corresponds to about 350 ppm CO₂.

To get to the 350 ppm CO₂ target put forward by Dr Hansen, the total greenhouse gas concentration will need to fall to about 400 ppm CO₂-equivalents. This is at the low end of a range of stabilisation concentration possibilities and is fully compatible with the EU 2-degrees-centigrade target.

The Tällberg Forum is holding an international conference in Sweden from 26 to 29 June 2008 to discuss how to achieve this lower level through 'The Perfect Agreement and its Perfect Implementation' as an idealised design of a global deal that will serve as a benchmark for the UN Framework Convention on Climate Change (UNFCCC). The Convention is aiming to reach an international climate change agreement in Copenhagen in December 2009.

James Hansen (who is addressing the US Congress to raise awareness on the 350 ppm target) and Kofi Annan, former UN Secretary-General are among King Carl XVI Gustaf of Sweden's guests at the Tällberg Forum.