The Sustainable Development Goals (SDGs) will define the priorities of the UN’s development agenda beyond 2015. But the reality of climate change impacts will render these aspirational goals almost impossibly challenging for the Least Developed Countries (LDCs) unless the current level of ambition in development and climate action is urgently increased. This briefing summarises our analysis of the projected impacts of climate change on the ability of the LDCs to achieve each SDG, based on evidence primarily from the Fifth Assessment Report (AR5) of the UN’s Intergovernmental Panel on Climate Change. We go on to recommend policy pointers for the LDCs and their partners for the upcoming negotiations on the post-2015 agenda, financing for development, and a new climate change agreement.