Nationally Determined Contributions (NDCs) are a core concept and national climate action plan under the Paris Agreement of 2015. They embody the efforts by each country to reduce national greenhouse gas (GHG) emissions and adapt to the impacts of climate change. The concept was institutionalized to solve the problem of achieving a universal, collective climate goal after the Kyoto Protocol (1997) only set binding targets for developed countries. The precursor to NDCs were the Intended Nationally Determined Contributions (INDCs), which were non-binding pledges requested at the 2013 United Nations Climate Change Conference in Warsaw, Poland.
The mechanism is outlined in the Paris Agreement, which is a treaty under the United Nations Framework Convention on Climate Change (UNFCCC). Article 4, paragraph 2 of the Agreement requires each Party to prepare, communicate, and maintain successive NDCs. This structure reflects the principle of Common but Differentiated Responsibilities and Respective Capabilities (CBDR-RC) by allowing countries to self-determine their targets based on national circumstances. A key provision is the 'ratchet mechanism,' which mandates that NDCs must be updated every five years and must represent a "progression" and reflect the Party's "highest possible ambition."
The process has recently been updated, with the third round of NDCs, sometimes called NDC 3.0, due in 2025 to cover actions through 2035. These new NDCs must be informed by the outcomes of the first Global Stocktake (GST), which assessed collective progress in 2023. The core requirement of a five-year update cycle and the principle of progression remain unchanged.