This paper explores the challenges of increasing climate finance to emerging markets and developing countries. It discusses the prospects for raising more public international finance in absolute terms, and proposes ideas for using the public money that is already available – or realistically likely to become available – more effectively. Key findings include: the need for regular comparative assessment of different channels for deploying public finance in climate action; the need to enable multilateral development banks genuinely to leverage risk-bearing private finance, and for public finance generally to be exposed to more risk; and the need to address moral hazard and other perverse incentives that still skew a large amount of private investment towards fossil fuels.