The global community has to act collectively to halt climate change. But such collective action must take into account the development needs of the least developed countries (LDCs), which are likely to be hit earliest and hardest by climate change. The priority of such countries remains poverty alleviation and the achievement of the Millennium Development Goals, but the three challenges of limiting climate change, adapting to its consequences and reducing poverty have to be faced together. This requires LDCs eventually to follow a development path that differs from those trodden by today’s industrial countries and emerging market economies. There is no room in the long term for high-emission economies, and high-carbon growth is unsustainable given the possible consequences for fossil-fuel supplies and climate-change impacts.