The Paris Agreement is a landmark international climate accord that was signed in 2016 by 196 countries around the world. The agreement aims to limit global warming to well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 degrees Celsius.

The Paris Agreement officially entered into force on November 4, 2016, 30 days after at least 55 countries, representing at least 55 percent of global greenhouse gas emissions, had deposited their instruments of ratification, acceptance, approval or accession with the UN Secretary-General.

As of today, 191 countries have ratified the Paris Agreement, with only a few countries such as Iran, Iraq, Eritrea, and Turkey still remaining to ratify. The United States, which is one of the biggest emitters of greenhouse gases, withdrew from the agreement in 2017 under the Trump administration but has since rejoined under the Biden administration.

The Paris Agreement is a legally binding treaty that sets out a framework for countries to work together to tackle climate change. It includes commitments from countries to report regularly on their emissions and to enhance their efforts over time. This means that each country has its own timeline for meeting its commitments under the Paris Agreement, depending on its national circumstances and capabilities.

The Paris Agreement provides a roadmap for a transition to a low-carbon economy, which will require significant investment in renewable energy and other low-carbon technologies. It also calls for greater international cooperation on climate change, including support for developing countries to adapt to the impacts of climate change and to pursue low-carbon development pathways.

In conclusion, the Paris Agreement officially started on November 4, 2016, after at least 55 countries, representing at least 55 percent of global greenhouse gas emissions, had deposited their instruments of ratification, acceptance, approval or accession with the UN Secretary-General. The agreement is a legally binding treaty that sets out a framework for countries to work together to tackle climate change and each country has its own timeline for meeting its commitments under the Paris Agreement.