Carbon dioxide, nitrous oxide and methane are gases that accumulate in the atmosphere and prevent heat from radiating from the Earth`s surface into space, creating the so-called greenhouse effect. According to the Intergovernmental Panel on Climate Change (IPCC), the leading international scientific body working on the issue, the concentration of these heat storage gases has increased dramatically since pre-industrial times to levels not seen in at least 800,000 years. Carbon dioxide (the main cause of climate change) has increased by 40%, nitrous oxide by 20% and methane by 150% since 1750 – mainly from the combustion of dirty fossil fuels. The IPCC says it is “extremely likely” that these emissions are mainly responsible for the rise in global temperatures since the 1950s. At the same time, deforestation and forest degradation have also contributed to their fair share of global carbon emissions. Ultimately, all parties have acknowledged the need to “avoid, minimize and treat loss and damage,” but in particular, any mention of indemnification or liability is excluded.  The Convention also adopts the Warsaw International Mechanism for Loss and Damage, an institution that will seek to answer questions on how to classify, address and share responsibility for losses.  President Obama was able to formally include the United States in the international agreement through executive action, as he did not impose any new legal obligations on the country. The U.S. already has a number of tools on its books, under laws already passed by Congress to reduce carbon pollution. The country formally acceded to the agreement in September 2016 after submitting its proposal for participation. The Paris Agreement could not enter into force until at least 55 countries representing at least 55% of global emissions had officially acceded to it.
This happened on October 5, 2016 and the agreement entered into force 30 days later, on November 4, 2016. On August 4, 2017, the Trump administration sent an official notice to the United Nations stating that the U.S. agreement also reminds the parties of the importance of government subsidies, as adjustment measures receive less public sector investment.  John Kerry, as Secretary of State, announced that the United States would double its subsidy-based adjustment funding by 2020.  The Paris Agreement is the first universal and legally binding global climate agreement adopted at the Paris Climate Change Conference (COP21) in December 2015. Although the United States and Turkey are not party to the agreement because they have not declared their intention to withdraw from the 1992 UNFCCC, as Annex 1 countries of the UNFCCC, they will continue to be required to produce national communications and an annual greenhouse gas inventory.  The Montreal Protocol was adopted in 1987 to phase out a group of chemicals, including chlorofluorocarbons or CFCs, that cause dangerous holes in the ozone layer. The agreement set strict limits on the production and consumption of CFCs used in air conditioners, refrigerators and industry, which have decreased over time. It also banned trade in chemicals or products they used between countries that had signed the agreement and those that had not. As more and more countries joined the pact, the global refrigerant market shrunk for those who had not signed, creating a turning point that almost forced countries to join once critical mass was reached.
The aim of the agreement is to reduce global warming described in Article 2 and improve the implementation of the UNFCCC by: Unlike the Kyoto Protocol, which sets legally binding emission reduction targets (as well as sanctions for non-compliance) only for developed countries, the Paris Agreement requires that all countries – rich, poor, developed and developed – do their part and reduce greenhouse gas emissions. To this end, greater flexibility is built into the Paris Agreement: it does not include language in the commitments that countries should make, countries can voluntarily set their emission targets (NDCs) and countries are not penalized if they do not meet the proposed targets. What the Paris Agreement requires, however, is monitoring, reporting, and reassessing countries` individual and collective goals over time in order to bring the world closer to the broader goals of the agreement. And the agreement stipulates that countries must announce their next set of targets every five years – unlike the Kyoto Protocol, which aimed at that target but did not contain a specific requirement to achieve it. Yes, there is a broad consensus in the scientific community, although some deny that climate change is a problem, including politicians in the United States. When negotiating teams come together for international climate negotiations, there is “less skepticism about science and more disagreement about how to set priorities,” says David Victor, a professor of international relations at the University of California, San Diego. The basic science is this: in fact, research clearly shows that the costs of climate inaction far outweigh the costs of reducing carbon pollution. A recent study suggests that if the United States fails to meet its Paris climate goals, it could cost the economy up to $6 trillion in the coming decades. A global failure to meet the NDCs currently set out in the agreement could reduce global GDP by more than 25% by the end of the century.
At the same time, another study estimates that meeting – or even exceeding – the Paris targets through infrastructure investments in clean energy and energy efficiency could have huge global benefits – around $19 trillion. .