A report by the Organisation for Economic Co-operation and Development (OECD) in collaboration with Climate Policy Initiative (CPI). Developed countries committed to jointly mobilize USD 100 billion a year in climate finance by 2020 for climate action in developing countries. With the aim of informing the international discussions and enhancing transparency on climate finance ahead of the UNFCCC 21st Conference of Parties (COP21) in Paris in December 2015, the current and incoming COP Presidencies, Peru and France, asked the Organisation for Economic Cooperation and Development (OECD) in collaboration with Climate Policy Initiative (CPI) to provide an up-to-date aggregate estimate of mobilized climate finance and an indication of the progress towards the UNFCCC climate finance goal. The preliminary estimates provided in this report are that climate finance reached USD 62 billion in 2014 and USD 52 billion in 2013, equivalent to an annual average over the two years of USD 57 billion and reflecting significant progress in meeting the goal. Bilateral public climate finance represents a significant proportion of this aggregate, provisionally estimated at USD 22.8 billion on average per year in 2013-14, representing an increase of over 50% relative to levels reported for 2011-12. Multilateral climate finance attributable to developed countries is estimated at USD 17.9 billion in 2013-14. The remaining finance reflects estimates of export credits and private finance mobilized by bilateral and multilateral finance attributable to developed countries (a partial estimate). The report aims to be transparent and rigorous in its assessment of the available data and the underlying assumptions and methodologies, within the constraints of an aggregate reporting exercise. Methodological approaches and data collection efforts to support estimates such as this one are improving. Nevertheless, there remains significant work to be done to arrive at more complete and accurate estimates in the future, as outlined in the report. The accounting framework and definitions that form the basis of these estimates are outlined in part one of the report.