Global Environmental Change 13 (2003) 277–293 Climate change: long-term targets and short-term commitments $ Jan Corfee-Morlot a , Niklas H . ohne b, * a OECD Environment Directorate, 2, rue Andr ! e Pascal, 75775 Paris Cedex 16, France b ECOFYS Energy and Environment, Eupener Strasse 59, Cologne 50933, Germany Abstract International negotiations under the UN Framework Convention on Climate Change could take several different approaches to advance future mitigation commitments. Options range from trying to reach consensus on specific long-term atmospheric concentration targets (e.g. 550 ppmv) to simply ignoring this contentious issue and focusing instead on what can be done in the nearer term. This paper argues for a strategy that lies between these two extremes. Internationally agreed threshold levels for certain categories of impacts or of risks posed by climate change could be translated into acceptable levels of atmospheric concentrations. This could help to establish a range of upper limits for global emissions in the medium term that could set the ambition level for negotiations on expanded GHG mitigation commitments. The paper thus considers how physical and socio-economic indicators of climate change impacts might be used to guide the setting of such targets. In an effort to explore the feasibility and implications of low levels of stabilisation, it also quantifies an intermediate global emission target for 2020 that keeps open the option to stabilise at 450 ppmv CO 2 If new efforts to reduce emissions are not forthcoming (e.g. the Kyoto Protocol or similar mitigation efforts fail), there is a significant chance that the option of 450 ppmv CO 2 is out of reach as of 2020. Regardless of the preferred approach to shaping new international commitments on climate change, progress will require improved information on the avoided impacts climate change at different levels of mitigation and careful assessment of mitigation costs. r 2003 Elsevier Ltd. All rights reserved. Keywords: Climate change; Climate change impacts; Greenhouse gas targets; Kyoto Protocol; United Nations Framework Convention on Climate Change; UNFCCC 1. Introduction Questions about the timing, level and form of the next round of mitigation commitments are moving to centre stage of the international negotiating agenda on climate change. A key will be to intensify and broaden participation in emission reduction so as to bring absolute global emissions trends down and allow stabilisation of concentrations of GHG to occur in a timely manner. The Kyoto Protocol calls for starting new negotiations on next steps by 2005. 1 The guiding objective for these future negotiations is found in the UN Framework Convention on Climate Change (UNFCCC, 1992): ‘‘to achievey stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change; to ensure that food production is not threatened and to enable economic development to proceed in a sustain- able manner’’ (Article 2). In addition, the Convention calls for ‘‘precautionary, cost-effective and equitable measures to address climate change’’ (Article 3.3). The Convention objective implies that questions pertaining to the level and timing of mitigation commitments derive from a common concern in the international community about the potential damages of climate change and the need to make timely progress in abating potentially ‘‘dangerous’’ climate change (Fig. 1). The IPCC Third Assessment Report laid out a way to begin to structure thinking about the risks of climate change, referring to five ‘‘areas of concern’’ (see Section 3 below): (i) risk of large scale singularities; (ii) aggregate impacts; (iii) distribution of impacts; ARTICLE IN PRESS $ This paper represents the views of the authors; it does not represent the views of the OECD nor its Member countries. *Corresponding author. E-mail addresses: jan.corfee-morlot@oecd.org (J. Corfee-Morlot), n.hoehne@ecofys.de (N. H . ohne). 1 Review of the Kyoto Protocol at the second Meeting of the Parties, which may take place in November 2005 (Article 9.2) and initiation of consideration of commitments for Annex I Parties in 2005 (Article 3.9). 0959-3780/$ - see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.gloenvcha.2003.09.001