What is COP21 – and why does it matter?

One of the biggest headlines to come out of last week’s G20 summit in China was the announcement that both China and the US had ratified the Paris Agreement on Climate Change.

The announcement was significant, because the US and China are the world’s two biggest polluters. China is responsible for 20.09% of global emissions, while the US is responsible for 17.89%.

What is the Paris agreement?

Climate change is one of the biggest challenges facing the world today. It is responsible for the increase in extreme weather events, as well as an unbroken series of hottest years on record. Indeed, the World Economic Forum’s Global Risks Report 2016 named it as one of biggest risks we face.

In recognition of this, 179 countries and the EU spent two weeks in Paris last December hammering out the final wording of an agreement to keep global temperature increase well below 2C and if possible, below 1.5C. The reduction in temperature can only be achieved through a significant reduction in the emission of greenhouse gases. Known as COP21, (The 21st Conference of the Parties to the UN Framework Convention on Climate Change), it was one of the largest gatherings of world leaders ever seen.

Everyone who attended COP21 made emission-cutting pledges. These are known as “intended nationally determined contributions”, or INDCs for short. The US, for example, pledged to cut U.S. climate pollution by 26-28% from 2005 levels. China’s target is to reach peak CO2 emissions by 2030 at the latest, lower the carbon intensity of GDP by 60% to 65% below 2005 levels by 2030, and to increase the share of non-fossil energy carriers of the total primary energy supply to around 20%.

The EU plans to cut emissions by 40% by 2030 on 1990 levels.

What will make the agreement come into force?

For the agreement to come into effect, at least 55 countries have to join it, and those countries have to represent 55% of global emissions. Once this is achieved, everyone will be obliged to meet their emissions-cutting pledges.

There are three steps that a country or party has to take before officially joining the agreement.

1. Adopt the agreement

This is what the meeting in December 2015 was all about. All the parties who attended the meeting agreed to - “adopted” - the text of the Paris Agreement on Climate Change.

2. Sign the agreement

On April 22, 2016, the Paris Agreement was opened for signature at the United Nations Headquarters in New York. This step indicates a commitment by that country to refrain from acts that would defeat the object and purpose of the Agreement. The Agreement will remain open for signature until April 2017.

3. Join the agreement

Each party has to ratify the agreement, i.e. go back to their domestic governments in order to gain domestic approval or, in some cases, have it passed by domestic law. China, for instance, voted to adopt "the proposal to review and ratify the Paris Agreement," at the closing meeting of the National People's Congress Standing Committee. The US used a presidential executive agreement. Once the Agreement is ratified the parties submit an “instrument of ratification, acceptance or approval” to the UN to prove that they are ready to join.

Why is the news about the US and China so significant?

Before the announcement by the US and China, only 24 countries – responsible for about 1% of global emissions – had ratified the agreement, while 180 had signed it.

The global emissions target of 55% has been significantly boosted by China and the US, who between them represent 37.98% of global emissions. This brings the total parties who have joined the Agreement to 26, and the percentage of global emissions to 39.06%.

Their announcement puts pressure on other participants – such as the EU – to speed up their ratifying process. Some of the world’s other large polluters, such as Japan, Brazil and Canada have all publicly said that they intend to ratify the agreement by the end of the year.

What happens if a party changes its mind?

Donald Trump, the Republican candidate for the US Presidential election, has said he will abandon the Paris agreement if he is elected. However, once a party has joined the agreement, they cannot begin the process of withdrawal for three years.

The Paris Agreement signifies years of work in trying to combat climate change. In 1992, countries joined an international treaty, the United Nations Framework Convention on Climate Change. In 2005, the Kyoto Protocol became a legally binding treaty. It committed its parties to internationally binding emission reduction targets. It ends in 2020, and COP21 is designed to take its place.