In 2007, the Nobel Prize winning Intergovernmental Panel on Climate Change (IPCC) report on the scientific basics of climate change synthesized various climate models. The IPCC concluded that dramatic emissions reductions were needed to stabilize atmospheric greenhouse gases (GHG) at 450 ppm CO2e by 2050. We’re currently at 387 ppm and climbing at a rate of about 2 ppm each year.
Stabilizing at 450 ppm may provide a 50 percent chance that the global average temperature increase can be contained to roughly 2˚C above pre-industrial levels and will, hopefully, limit the catastrophic and irreversible outcomes of climate change.
Since that IPCC report, more scientific findings have revealed that “the worst-case IPCC scenario trajectories are being realized.” It seems that 450 ppm may not be enough. The world may need to make even more drastic emissions reductions than those recommended only two years ago.
There is a growing belief among scientists and policy makers that the 450 ppm target is too high to avert climatic catastrophe. What would such a climate catastrophe entail? The loss of island nations, some 200 million climate refugees by 2050, 40 percent of plant and animals extinct, nearly a third of the world’s land surface at risk of extreme drought and the potential loss of the Amazon rainforest. In light of the frightening evidence of the true impacts of a 450 ppm world, there is a push to take on an even greater challenge — aiming to stabilize at 350 ppm or below.
In the company of a wide range of scientists (most prominently, NASA’s Dr. James Hansen), President Mohammed Nasheed of the Maldives advocates this 350 ppm goal. He explains it as an issue of life or death: if this goal is exceeded, his island nation — most of which exists at seven feet above sea level — will be submerged. For the Maldives, 450 ppm won’t cut it. To make this life or death point, the President and his cabinet took to the seas and held an October cabinet meeting underwater.
It can be challenging for individuals to feel empowered to act to address climate change. Still, advocates of the 350 ppm target have been lobbying nations to officially endorse that goal — and strategies to achieve it — in the agreement they are working toward under the United Nations Framework Convention on Climate Change.
More information on the search to find a “safe” target level for avoiding catastrophic climate change can be found in an article that recently appeared in The New York Times.
 Intergovernmental Panel on Climate Change 4th Assessment Report, Working Group III report. Climate Change 2007: Mitigation of Climate Change (Cambridge University Press, Cambridge, 2007), chapter 13, Box 13.7 (776).
 Intergovernmental Panel on Climate Change 4th Assessment Report, Working Group I report: Climate Change 2007: The Physical Science Basis (Cambridge University Press, Cambridge, 2007), chapter 10, Table 10.8 (page 826).
Intergovernmental Panel on Climate Change 4th Assessment Report, Working Group I report: Climate Change 2007: The Physical Science Basis (Cambridge University Press, Cambridge, 2007), chapter 10, Supplementary Figure S10.4. (page Sm.10-8).
Meinshausen, M. (2006): ‘What does a 2°C target mean for greenhouse gas concentrations? A brief analysis based on multi-gas emission pathways and several climate sensitivity uncertainty estimates’, pp.253 – 280 in Avoiding dangerous climate change, H.J. Schellnhuber et al. (eds.), Cambridge: Cambridge University Press.
 Associated Press, March 12,2009, http://climatecongress.ku.dk