A preliminary inventory-impact study was published in Nature Communications in April 2020. Based on a public policy database and a multi-model scenario analysis, the authors showed that the implementation of current strategies by 2030 leaves an average emission gap of 22.4 to 28.2 GtCO2eq, with optimal means to achieve targets well below 2 degrees Celsius and 1.5 degrees Celsius. If national contributions were fully implemented, this gap would be reduced by one-third. The countries assessed did not achieve their promised contributions with implemented measures (implementation deficit) or experienced a gap in ambition with optimal paths to well below 2oC. The study showed that all countries should accelerate the implementation of renewable technology strategies, while improving efficiency in emerging and fossil fuel-dependent countries is particularly important.  Since November 2020, 194 states and the European Union have signed the agreement. 187 countries and the EU, which account for about 79% of global greenhouse gas emissions, have ratified the agreement or have joined the agreement, including China and India, the countries with the first and third largest CO2 emissions among UNFCCC members.    As of November 2020[update], the United States, Iran and Turkey are the only countries with more than 1% not to be contracting parties. Ensure that both parties sign the agreement and that the document is recognized by two witnesses or a notary for both parties who rely on the document to verify their credibility. 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.  Countries are also working to reach “the global peak in greenhouse gas emissions” as soon as possible. The agreement has been described as an incentive and engine for the sale of fossil fuels.   Since the Kyoto Protocol came into force, the Clean Development Mechanism has been criticized because, in most cases, it has not brought significant emission reductions or benefits for sustainable development.  It has also suffered from low prices from Certified Emission Reductions (REFs), which has reduced project demand.