Montreal Protocol, 1987. Although the Montreal Protocol [PDF] was not designed to combat climate change, it is a historic environmental agreement that has become a model for future climate change diplomacy. Every country in the world has finally ratified the treaty that required them to stop the production of substances that harm the ozone layer, such as chlorofluorocarbons (CFCs). The Protocol has succeeded in eliminating nearly 99% of these ozone-depleting substances. In 2016, the parties agreed to modify Kigali to also reduce their production of partially fluorinated hydrocarbons (HFCs), powerful greenhouse gases that contribute to climate change. A study published in 2018 reports a threshold where temperatures could rise to 4 or 5 degrees above the pre-industrial level (ambiguous expression, continuity would be “4-5 °C”), thanks to self-concretizing feedbacks in the climate system, indicating that this threshold is below the 2 degree target set in the Paris Climate Agreement. Study author Katherine Richardson points out, “We find that, in its history, the Earth has never had a near-stable state about 2°C warmer than pre-industrial and we suggest that there is a considerable risk that the system itself, because of all these other processes, will want,” even if we stop emissions. This doesn`t just mean reducing emissions, but much more.  In the context of this debate, important climate agreements have evolved in terms of how they seek to reduce emissions. The Kyoto Protocol only required industrialized countries to reduce emissions, while the Paris Agreement recognized that climate change was a common problem and required all countries to set emission targets. Negotiators for the agreement said the INDCs presented at the time of the Paris conference were insufficient and noted “with concern that estimates of aggregate greenhouse gas emissions in 2025 and 2030, resulting from projected national contributions, did not fall under the least expensive 2°C scenarios, but would end at a projected level of 55 gigatonnes in 2030.” and recognizing that “much greater efforts will be needed to reduce emissions in order to keep the global average temperature rise to less than 2°C by reducing emissions to 40 gigatons or 1.5°C”.  [Clarification needed] (c) reconciling financial flows with a path towards low greenhouse gas emissions and climate-resilient developments. Paris Agreement, comprehensive Paris Agreement Within the framework of the United Nations Framework Convention on Climate Change, also known as the Paris Climate Convention or COP21, an international treaty, named after the city of Paris, France, which adopted it in December 2015, which aimed to reduce gas emissions contributing to global warming.
The Paris Agreement aimed to improve and replace the Kyoto Protocol, a previous international agreement to reduce greenhouse gas emissions. It entered into force on 4 November 2016 and was signed by 194 countries and ratified by 188 in November 2020. Before Trump took power, the U.S. had pledged to reduce emissions by 26 to 28 percent below 2005 levels by 2025 — a goal it cannot meet. Biden has promised to invest nearly $2 trillion in clean energy and low-carbon infrastructure, but he hasn`t said what emissions reduction target he could set for himself if he becomes president. . . .