Joeri Rogelj et al., Nature Climate Change, Emission pathways consistent with a 2 °C global temperature limit

Nature Climate Change, doi:10.1038/nclimate1258

Emission pathways consistent with a 2 °C global temperature limit 

Joeri Rogelj, William Hare, Jason Lowe, Detlef P. van Vuuren, Keywan Riahi, Ben Matthews, Tatsuya Hanaoka, Kejun Jiang and Malte Meinshausen

Received 16 June 2011, accepted 22 September 2011, published online 23 October 2011.

 

Abstract 

 

In recent years, international climate policy has increasingly focused on limiting temperature rise, as opposed to achieving greenhouse-gas-concentration-related objectives. The agreements reached at the United Nations Framework Convention on Climate Change conference in Cancun in 2010 recognize that countries should take urgent action to limit the increase in global average temperature to less than 2 °C relative to pre-industrial levels¹. 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. Here we consider both of these aspects by reanalysing a large set of published emission scenarios from integrated assessment models in a risk-based climate modelling framework. 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.

 

 http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1258.html