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. All remaining parties to the agreement must present their new 2030 targets before the next major UN climate meeting, to be held in Glasgow, UK, in November 2021 (this year`s climate summit has been postponed due to the pandemic). To date, only 14 revised objectives have been proposed or presented. Article 7.4 outlines the co-economic benefits of adaptation and mitigation and highlights the importance of adaptation to climate change, thereby consolidating the parity between adaptation and mitigation. The article states that « current adjustment needs are significant and a higher level of mitigation may reduce the need for additional adjustment. »  Article 7 also deals with the financial aspects of adaptation. In particular, « a greater need for adjustment may result in higher adjustment costs. »  The 2015 pioneering agreement aims to limit global warming to a level « significantly below » 2 degrees Celsius above pre-industrial temperatures.
But in June 2017, U.S. President Donald Trump announced that the United States – the world`s second-largest emitter of greenhouse gases – would pull out of the agreement. While mitigation and adjustment require more climate funding, adjustment has generally received less support and has mobilized fewer private sector actions.  A 2014 OECD report showed that in 2014, only 16% of the world`s financial resources were devoted to adaptation to climate change.  The Paris Agreement called for a balance between climate finance between adaptation and mitigation, highlighting in particular the need to strengthen support for adaptation from the parties most affected by climate change, including least developed countries and small island developing states. The agreement also reminds the parties of the importance of public subsidies, as adjustment measures receive less public sector investment.  John Kerry, as Secretary of State, announced that the United States would double its grant-based adjustment funding by 2020.  Although the agreement has been welcomed by many, including French President Francois Hollande and UN Secretary-General Ban Ki-moon, criticism has also emerged. James Hansen, a former NASA scientist and climate change expert, expressed anger that most of the agreement is made up of « promises » or goals, not firm commitments.  He called the Paris talks a fraud with « nothing, only promises » and believed that only a generalized tax on CO2 emissions, which is not part of the Paris agreement, would force CO2 emissions down fast enough to avoid the worst effects of global warming.
  Kathleen Mogelgaard – Heather McGray, When Adaptation Is Not Enough: Paris Agreement « Loss and Damage, » World Res. Inst. (December 24, 2015), www.wri.org/blog/2015/12/when-adaptation-not-enough-paris-agreement-recognizes « loss-and-damage. » To achieve the overall goal of the Paris Agreement, international and national cooperation is needed.