Long-term goals and post-2012 commitments: where do we go from here with climate policy?

With entry into force of the Kyoto Protocol in 2005, climate change negotiators are turning their attention to the question, 'Where do we go from here?'. A key component of answering this question is in understanding the implications for society of alternative long-term goals for greenhouse gas concentrations. One challenge in ongoing negotiations is whether and how to deal with meanings of 'dangerous interference' as outlined in Article 2 of the UN Framework Convention on Climate Change. This study addresses Article 2 by suggesting the use of long-term goals to guide decisions about the stringency and timing of future climate change commitments. Focusing on mitigation policy benefits and, in particular, on avoiding long-term climate impacts, a number of management approaches and their implications are highlighted. After discussing some challenges of using scientific knowledge to monitor and manage progress, we look at what we can learn from current climate change global impact literature. Solid benchmark indicators appear to be available from global mean temperature change, ecosystems and coastal zone impacts information. We conclude by arguing for global goal-setting based on climate change effects and the use of indicators in these areas as part of post-2012 climate change negotiations. Aggregate global impacts suggest that 3-4°C of global mean temperature increase by 2100 (compared to a reference period of 1990) may be a threshold beyond which all known sector impacts are negative and rising with increasing levels of warming. However, marginal benefits may accrue at lower levels of mean change. Thus, a prudent policy might aim for significantly lower levels and slower rates of global warming.