Limiting global average temperature rise to 2 °C may be slipping from the world's grasp without urgent action this decade on emission reduction to combat climate change according to new review of climate modeling of emission pathways by a team lead by Dr Joeri Rogelj.
The two degree limit on global warming was adopted in 2009 at Copenhagen and reaffirmed a year later at the UN climate conference in Cancun.
"If this is to be achieved, policymakers need robust information about the amounts of future greenhouse-gas emissions that are consistent with such temperature limits. This, in turn, requires an understanding of both the technical and economic implications of reducing emissions and the processes that link emissions to temperature." says the study, published in Nature Climate Change on October 23, 2011.
"We find that in the set of scenarios with a ‘likely’ (greater than 66%) chance of staying below 2 °C, emissions peak between 2010 and 2020 and fall to a median level of 44 Gt of CO2 equivalent in 2020 (compared with estimated median emissions across the scenario set of 48 Gt of CO2 equivalent in 2010). Our analysis confirms that if the mechanisms needed to enable an early peak in global emissions followed by steep reductions are not put in place, there is a significant risk that the 2 °C target will not be achieved."
For each single degree Celsius (1.8 degree Fahrenheit) of additional warming, 5 to 10 percent less rain falls in the U.S. Southwest, the Mediterranean and southern Africa; 5 to 10 percent less streamflow occurs in some river basins, including the Arkansas and Rio Grande; and 5 to 15 percent crop-yield declines occur in corn in the United States and Africa, and wheat in India. Read more on the likely impacts from Warming World: Impacts by Degree (PDF 8.25mb) by the US National Academy of Sciences.
See the Global Emissions Gap scoreboard to see how poor we are doing in limiting temperature rise this century.
The next global climate talks are set for the Durban Conference of the Parties - COP17 - to be held in South Africa from 28 November - 9 December 2011.
- Nature Climate Change, October 23, 2011 - Emission pathways consistent with a 2 °C global temperature limit