Faced with the challenge of converting pledges to slash planet-warming emissions into policies, some of the world's biggest economies are turning to the same tool: a carbon price.
Globally, about 22% of global emissions are covered by the 46 national and 32 sub-national carbon pricing schemes operating today or in the planning stage, according to the World Bank.
Carbon pricing can come in the form of a tax or under a an emissions-trading, or cap-and-trade, scheme where companies or countries face a carbon limit
Below are some of the major carbon emissions trading systems (ETS) around the world.
A national ETS could be launched in 2021 following pilot schemes in provinces and cities including Beijing, Chongqing, Guangdong, Hunan, Shanghai, Shenzhen and Tianjin. They cover energy production and various energy-intensive industries.
The world's largest ETS, which started out 15 years ago, is mandatory for all 27 EU members, plus Iceland, Liechtenstein and Norway, covering power plants, aviation, energy intensive industries.
Its scheme, started in 2013. It was suspended 2016 and relaunched in 2018 after under going reforms. It covers the energy sector, mining and chemical industries.
A three-year pilot scheme was launched in 2020 covering the power, oil and gas, and industrial sectors.
Its ETS, which began in 2008, covers electricity generators, manufacturers liquid fossil fuels including petrol and diesel. Some forest owners are given free permits, others can voluntarily join the scheme.
Scheme was launched in 2012 and covers electricity, energy intensive industrials.
ETS started in 2015. It covers around 600 of the biggest emitters, collectively responsible for almost 70% of the country's annual emissions.
The United States does not have a national ETS, but many regions and states use carbon pricing, such as California and states covered by the Regional Greenhouse Gas Initiative (RGGI) - Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New York, Rhode Island, and Vermont.