climat.be: Nationally Determined Contributions and evaluation cycles
Another key point to note is that the agreement is now legally binding: each party is required to prepare, communicate and comply with nationally determined contributions (NDCs) and undertake domestic preparations towards achieving the set objectives.
The binding or non-binding nature of contributions was initially viewed as a potential stumbling block for the USA, since President Obama expressed fears at the time that the agreement would not gain US approval. The priority for the EU and many other countries was precisely to make the implementation of national objectives and plans of action as binding as possible. In order to avoid a deadlock, it was decided that the agreement - which does not include the mitigation targets proper- should establish an international obligation to set such targets and compel countries to implement policies specifically aimed at achieving these objectives.
Individual climate objectives and plans submitted by 188 countries before and during the COP21 are not yet on track to reach the 2°C goal, thus the agreement provides a five-year assessment cycle during which each country is required to communicate new national and increasingly robust contributions. The aim is equally for all the countries’ contributions to evolve over time into absolute national emissions ceilings similar to the ones that already obtain in industrialized countries.