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. The Kyoto Protocol, a pioneering environmental treaty adopted at COP3 in Japan in 1997, is the first time nations have agreed on country-by-country emission reduction targets. The protocol, which only came into force in 2005, set binding emission reduction targets only for industrialized countries, based on the fact that they are responsible for most of the world`s high greenhouse gas emissions. The United States first signed the agreement, but never ratified it; President George W. Bush argued that the agreement would hurt the U.S. economy because developing countries such as China and India would not be included. In the absence of the participation of these three countries, the effectiveness of the treaty was limited, as its objectives covered only a small fraction of total global emissions.
Each country in the United Nations Framework Convention on Climate Change (UNFCCC) (195 countries in total) and the EU institution (the 196th member) have accepted the terms of the Paris Agreement – the UNFCCC can only adopt agreements without objection, there is no room for a majority agreement. The Paris Agreement was unanimously adopted. Risks are increasing because, historically, these agreements only become ambitious over time. In other words, the Paris framework is a starting point, no matter how bad, it is not an end point. And the exit from the agreement protects the United States from future violations of U.S. sovereignty and from any future massive legal liability. Believe me, we have a massive legal responsibility if we continue to do so. The other Holdout, Uzbekistan, finally signed the agreement last month. The delay is due to the complex rules introduced in the Paris agreement to deal with the possibility that a future US president will decide to withdraw the country from the agreement.
«What Obama did at the end of his second term was fundamentally undemocratic to sign a Paris agreement without going to the Senate and Congress and doing it instead through an executive,» said former U.N. climate chief Yvo De Boer. There are also serious legal and constitutional issues.