"[3] The UN Framework Convention on Climate Change (UNFCCC), adopted at the 1992 Earth Summit is one of the first international treaties on the topic.

[22] According to one commentator two ways in which the French increased the likelihood of success were: firstly to ensure that Intended Nationally Determined Contributions (INDCs) were completed before the start of the negotiations, and secondly to invite leaders just for the beginning of the conference.

[24] At the conclusion of COP21 (the 21st meeting of the Conference of the Parties), on 12 December 2015, the final wording of the Paris Agreement was adopted by consensus by the 195 UNFCCC participating member states and the European Union.

[31] On 1 April 2016, the United States and China, which represent almost 40% of global emissions confirmed they would sign the Paris Climate Agreement.

A strong preference was reported that the EU and its 28 member states ratify at the same time to ensure that they do not engage themselves to fulfilling obligations that strictly belong to the other,[40] and there were fears by observers that disagreement over each member state's share of the EU-wide reduction target, as well as Britain's vote to leave the EU might delay the Paris pact.

[49][50] President Joe Biden signed an executive order on his first day in office, 20 January 2021, to re-admit the United States into the Paris Agreement.

[53][5] United States Climate Envoy John Kerry took part in virtual events, saying that the US would "earn its way back" into legitimacy in the Paris process.

The Intended Nationally Determined Contributions pledged during the 2015 Climate Change Conference are converted to NDCs when a country ratifies the Paris Agreement, unless they submit an update.

[68] Some of the pledges in the NDCs are unconditional, but others are conditional on outside factors such as getting finance and technical support, the ambition from other parties or the details of rules of the Paris Agreement that are yet to be set.

These procedures include the obligation to prepare, communicate and maintain successive NDCs, set a new one every five years, and provide information about the implementation.

[81] Broadly, it outlines the cooperative approaches that parties can take in achieving their nationally determined carbon emissions reductions.

The agreement recognizes the rights of parties to use emissions reductions outside of their own borders toward their NDC, in a system of carbon accounting and trading.

[85] Because the NDCs, and domestic carbon trading schemes, are heterogeneous, the ITMOs will provide a format for global linkage under the auspices of the UNFCCC.

Implementation also requires fossil fuel burning to be cut back and the share of sustainable energy to grow rapidly.

[101] In December 2020, the former chair of the COP 21, Laurent Fabius, argued that the implementation of the Paris Agreement could be bolstered by the adoption of a Global Pact for the Environment.

[105] According to the 2020 United Nations Environment Programme (UNEP), with the current climate commitments of the Paris Agreement, global mean temperatures will likely rise by more than 3 °C by the end of the 21st century.

[105] According to the stocktake report, the agreement has a significant effect: while in 2010 the expected temperature rise by 2100 was 3.7–4.8 °C, at COP 27 it was 2.4–2.6 °C and if all countries will fulfill their long-term pledges even 1.7–2.1 °C.

[116] In September 2021, the Climate Action Tracker estimated that, with current policies, global emissions will double above the 2030 target level.

Countries such as Iran, Russia, Saudi Arabia, Singapore, and Thailand have been criticised of not doing enough to meet the requirements of the agreement, and are on track to achieve a 4 °C warming of the planet if current policies are implemented more widely.

[117] The Production Gap 2021 report states that world governments still plan to produce 110% more fossil fuels in 2030 (including 240% more coal, 57% more oil and 71% more gas) than the 1.5 degree limit.

[126] The push to address loss and damage as a distinct issue in the Paris Agreement came from the Alliance of Small Island States and the Least Developed Countries, whose economies and livelihoods are most vulnerable to the negative effects of climate change.

[60] The Warsaw Mechanism, established two years earlier during COP19 and set to expire in 2016, categorizes loss and damage as a subset of adaptation, which was unpopular with many countries.

[127] The United States argued against this, possibly worried that classifying the issue as separate from adaptation would create yet another climate finance provision.

[126] The parties are legally bound to have their progress tracked by technical expert review to assess achievement toward the NDC and to determine ways to strengthen ambition.

[128] Article 13 of the Paris Agreement articulates an "enhanced transparency framework for action and support" that establishes harmonized monitoring, reporting, and verification (MRV) requirements.

[129] Parties to the agreement send their first Biennial Transparency Report (BTR), and greenhouse gas inventory figures to the UNFCCC by 2024 and every two years after that.

[129] Flexibility can be incorporated into the enhanced transparency framework via the scope, level of detail, or frequency of reporting, tiered based on a country's capacity.

After an initial ruling against the government in 2015 that required it to maintain its planned reduction, the decision was upheld on appeals through the Supreme Court of the Netherlands in 2019, ruling that the Dutch government failed to uphold human rights under Dutch law and the European Convention on Human Rights by lowering its emission targets.

[135] The Office of the United Nations High Commissioner for Human Rights officially recognized that "Climate change threatens the effective enjoyment of a range of human rights including those to life, water and sanitation, food, health, housing, self-determination, culture and development.

[138][139] When the agreement achieved the required signatures in October 2016, US President Barack Obama said that "Even if we meet every target, we will only get to part of where we need to go.