How Close Are We to the Two Degree Limit?


    UNEP Governing Council Meeting & Global Ministerial Environment Forum
    24-26 February, 2010 Bali, Indonesia
    By Chief Scientists Office, UNEP, in conjunction with representatives
    from nine scientific groups.

    Copenhagen and the two degree limit
    An important outcome of the Copenhagen Accord, noted at the end of the UN climate convention meeting in December 2009, was the declaration that “deep cuts in global emissions are required … with a view to reduce global emissions so as to hold the increase in global temperature below 2 degrees Celsius.”1 Based on current understanding of climate change science, scientists believe that the two degree limit will provide a measure of assurance that we can avoid many climate impacts.2 Furthermore, this aim provides a scientific underpinning to the Accord and establishes a benchmark for comparing emission commitments and mitigation actions submitted to the UN Framework Convention on Climate Change (UNFCCC).
    Now that this limit is enshrined in the Accord, the key question is, will emission reduction commitments/mitigation actions for 2020 be consistent with the two degree limit? Or put another way, will the world be on an emissions pathway compatible with a limit of two degrees temperature increase?
    The aim of this paper is to sum up recent insights into these questions. To do so we divide the larger issue into three parts: