The agreement stated that it would only enter into force (and therefore fully effective) if 55 countries that produce at least 55% of global greenhouse gas emissions (according to a list drawn up in 2015)  ratify, accept, approve or adhere to the agreement.   On April 1, 2016, the United States and China, which together account for nearly 40% of global emissions, issued a joint statement confirming that the two countries would sign the Paris climate agreement.  175 contracting parties (174 states and the European Union) signed the agreement on the first day of its signing.   On the same day, more than 20 countries announced plans to join the accession as soon as possible in 2016. The ratification by the European Union has achieved a sufficient number of contracting parties to enter into force on 4 November 2016. While the enhanced transparency framework is universal and the global inventory is carried out every five years, the framework must provide „integrated flexibility“ to distinguish the capabilities of developed and developing countries. In this context, the Paris Agreement contains provisions to improve the capacity-building framework.  The agreement recognizes the different circumstances of some countries and notes, in particular, that the technical review of experts for each country takes into account the specific capacity of that country to report.  The agreement also develops a capacity-building initiative for transparency to help developing countries put in place the necessary institutions and procedures to comply with the transparency framework.  COP24 in Poland ended with mixed results. Countries agree on an agreement to implement the Paris Agreement, but are not resolved the key issues concerning a global carbon trading system and how to respond to warnings against a temperature increase above 1.5 degrees Celsius. President Obama was able to formally enshrine the United States in the agreement through executive measures because he did not impose new legal obligations on the country. The United States already has a number of instruments on the books, under laws already passed by Congress to reduce carbon pollution.
The country officially joined the agreement in September 2016, after submitting its request for participation. The Paris Agreement was only able to enter into force after the formal accession of at least 55 nations representing at least 55% of global emissions. This happened on October 5, 2016 and the agreement came into force 30 days later, on November 4, 2016. InDCs become CNDs – nationally determined contributions – as soon as a country formally adheres to the agreement. There are no specific requirements as to how or how many countries should reduce emissions, but there were political expectations about the nature and rigour of the targets set by different countries. As a result, the scale and ambition of national plans vary widely, largely reflecting each country`s capacity, level of development and contribution to emissions over time. China, for example, has committed to cleaning up its CO2 emissions by 2030 at the latest and reducing CO2 emissions per unit of gross domestic product (GDP) by 60-65% by 2030 from 2005 levels. India has set a target of reducing emissions intensity by 33-35% from 2005 levels by 2030 and producing 40% of its electricity from non-fossil fuels. The Durban conference in South Africa nearly collapsed after the world`s three biggest polluters – China, India and the United States – rejected a deal proposed by the European Union.
But they finally agreed to work on a new legally binding agreement by 2015. The new agreement will be different from the Kyoto Protocol in that it will apply to both developed and developing countries. Since the Kyoto Protocol is expected to expire in a few months, the parties agree to extend it until 2017.