The Fourth Assessment Report of the Intergovernmental Panel on Climate Change confirmed that anthropogenic greenhouse gas emissions are having significant and negative impacts on the climate, emphasized the dangers of rising global mean temperatures and associated changes in precipitation patterns and extreme weather events, and provided an assessment of the means and costs of combating climate change. The message is clear: Accelerated action is urgently needed on mitigation, in order to address the causes of climate change and avoid future catastrophic consequences. At the same time, efforts for adaptation to current and future impacts must be stepped up.

The economic, social and environmental consequences of climate change, combined with its potentially irreversible nature, confront the international community with one of its most complex and serious challenges. The high-level event on climate change, convened by the United Nations Secretary-General on 24 September 2007 to galvanize political consensus, saw the unequivocal commitment of world leaders to concerted action. They agreed that the United Nations provides the appropriate multilateral framework for action and that the United Nations Framework Convention on Climate Change is the only forum in which international action can be agreed.

The present document prepared by the United Nations System Chief Executives Board for Coordination (CEB), gives an overview of ongoing UN system actions in key climate change-related areas, in support of national endeavours and in furtherance of the implementation of mandates received through the UNFCCC and other intergovernmental bodies.

Rationale for action

Observable trends of ongoing climate change and current projections indicate increasingly severe negative impacts on all countries, with the most severe impacts disproportionately affecting the poorest countries with the weakest capacity for climate resilience. Equally, within countries, climate change is disproportionately affecting the poor and vulnerable in society.