The Paris Agreement is a historic treaty aimed at mitigating climate change by reducing greenhouse gas emissions. It was adopted by 195 countries in Paris, France, in December 2015 and went into effect on November 4, 2016. The agreement has since been signed by nearly all of the world`s nations, making it one of the most widely supported international treaties in history.

As of 2021, there are 197 parties to the Paris Agreement, including 196 countries and the European Union. The only country that has not signed the agreement is Syria, which is currently in the midst of a civil war. However, Syria has expressed its intention to join the Paris Agreement, and it is expected to do so in the near future.

The United States, which is the world`s second-largest emitter of greenhouse gases, initially signed the Paris Agreement under President Barack Obama in 2015. However, in 2017, President Donald Trump announced that the US would withdraw from the agreement, citing concerns about economic competitiveness and the role of the US in global affairs. The withdrawal was completed in November 2020, but President Joe Biden immediately announced the US`s intention to rejoin the agreement, which was accomplished on February 19, 2021.

Other major emitters of greenhouse gases, such as China, India, Russia, the European Union, and Japan, are all parties to the Paris Agreement. These countries have pledged to reduce their emissions through a combination of mitigation and adaptation measures, with the goal of limiting global warming to well below 2 degrees Celsius above pre-industrial levels.

The Paris Agreement represents a major step forward in the fight against climate change, as it provides a framework for global cooperation and action on this critical issue. While there is still much work to be done to achieve the goals of the agreement, the fact that nearly all of the world`s nations have signed on is a testament to the urgency and importance of addressing this pressing issue.