Climate change is increasingly affecting the process and content of foreign policy and, largely as a result of stronger scientific evidence as to its causes and possible consequences, has reached an increasingly formative stage in international policy negotiations. It is now beyond any reasonable doubt that climate change is happening, that its predominant cause is the growing concentration of greenhouse gases in the atmosphere, and that these greenhouse gases stem primarily from human activities. The first effects of climate change are already being observed, and further impacts are inevitable. Adaptation to these impacts will therefore be an unavoidable part of national and international policy responses to climate change, along with mitigation (i.e., reducing greenhouse gas emissions and enhancing sinks). The Stern Review on the Economics of Climate Change estimates that if

no action is taken to mitigate climate change, overall damage costs will be equivalent to losing at least 5 per cent of global gross domestic product (GDP) each year, with higher losses in most developing countries (Stern 2007). The World Bank (2006) concludes that the incremental costs to adapt to projected impacts of climate change in developing countries are likely to be in the order of US$ 10-40 billion per year, while Oxfam International (2007) estimates this number to be more than US$ 50 billion per year. The UNFCCC (2007) reckons that by 2030 the annual costs of adaptation in developing countries will amount to US$ 28-67 billion. The UNDP (2007) has the most pessimistic estimate to date: it suggests that aid financing requirements for adaptation could amount to US$ 86 billion per year by 2015. These numbers show that climate change is not only or even primarily an

environmental challenge: for the largest part of the world it is, above anything else, a development challenge. The seminal report Poverty and Climate Change: Reducing the Vulnerability of the Poor through Adaptation, prepared by ten bilateral and multilateral donor organizations, concludes that climate change presents a challenge to meeting important development objectives, including the Millennium Development Goals (Sperling 2003). It recommends that adaptation be designed so as to be consistent with development priorities and concludes that to consider climate change in development activities could add a long-term sustainability component to official

in of change to the ODA activity and its deliverables (e.g., water supply, food security); (2) the vulnerability to climate change of the community or ecosystem that is the beneficiary of the ODA activity; and (3) the possible effects of the ODA activity and its deliverables on the vulnerability of communities or ecosystems to climate change. Given these linkages and the broad and multifaceted nature of adaptation

activities (which will be further described below), it is clear that adaptation is relevant to consider in several fields of foreign policy towards vulnerable countries in the developing world. Donor agencies are increasingly expressing the need to integrate adaptation to climate change into mainstream development assistance activities. In April 2006, the OECD Development Assistance Committee and Environment Policy Committee agreed on a Declaration on Integrating Climate Change Adaptation into Development Co-operation. This integration process, often referred to as mainstreaming, is still lacking a sound theoretical foundation on the basis of which it would be possible, for example, to evaluate or predict the success of mainstreaming efforts and to identify challenges that need to be overcome when moving from planning to implementation. This chapter outlines the contours of what should become a theoretical foundation for mainstreaming adaptation into development, by unpacking the concepts of mainstreaming and adaptation respectively, proposing key dimensions of mainstreaming, and identifying key factors for ensuring successful mainstreaming. It draws on theory and lessons from the wider field of integration of environmental objectives and concerns in sector policies (e.g., energy policy, agricultural policy), a field usually referred to as environmental policy integration (EPI). EPI has been identified as a cornerstone of sustainable development (WCED 1987) and a body of EPI literature has emerged in recent years, in particular in Europe (e.g., Lenschow 2002; Nilsson and Persson 2003; EEA 2005; Nilsson and Eckerberg 2007). A weakness of the existing EPI literature, however, is that it has been mainly concerned with integration in a domestic policy-making context. This chapter aims to contribute with a perspective on integration challenges in foreign policy-making context, namely that of ODA (see also Palerm et al. 2007, for a discussion of EPI in the context of European ODA).