UNEP Analysis of How to Avoid Exceeding the 2C Limit

UNEP recently released a new analysis (10 pages) this week of what additional steps States need to take to meet the Copenhagen Accord goal of avoiding a temperature increase of 2C above Pre-Industrial levels. It provides some interesting insights also as to temporal considerations in climate policy making.

Among the important take-aways of the report:

  1. The level of cumulative emissions “play a decisive role” in determining compatible emissions pathways with a 2C limit;
  2. According to recent studies, there is a medium likelihood (defined as a 50% chance) to stay within the 2C limit if global emissions peak between 2015-2021, global emissions in 2020 are 40-48.3 GtCO2-eq./yr, adn global emissions decrease by 48-72% by 2050 relative to 2000. However, there are many sources of uncertainty in estimating emission pathways;
  3. Based on the upper and lower ranges of the pledges made by UNFCCC Parties post-COP15, the gap between high pledges and what’s necessary is about 0.5-8.8 Gt Co2 eq./yr., with an intermediate value of 4.7; if low emission pledges are fulfilled, the gap is between 2.9-11.2 Gt CO2 eq./yr., with an intermediate value of 7.1;
  4. Even if the intermediate targets are met, further reductions after 2020 are necessary, with most studies indicating that reduction rate at peak should be at least 3% annually; thus, it would be salutary to set international emission targets also for 2050, as well as long-term targets to stimulating the requisite R&D for technologies e.g. carbon capture and sequestration and new resource-efficient technologies;
  5. There is low confidence that the two degree limit will be met under current emissions scenarios.

Of course this study makes several assumptions that lead us to believe that the actual gap may be evne wider. For example, the prospects for the United States to meet its pledge appear increasingly remote as climate change legislation founders in the Senate and the EPA may be backtracking on its intention to regulate emissions under the Clean Air Act. Moreover, a number of analyses have questioned the integrity of many components of the pledges, especially in the context of LULUCF and offsets.

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