In advance of last weeks G20 economic summit, the skies over the city of Hangzhou, China, turned APEC Blue a phrase that was coined by residents of Beijing when the Asian Pacific Economic Conference was held there eight years ago. Factories were closed, traffic was restricted, and air pollution temporarily vanished. President Obama and the leaders of 19 other major global economies got to see one of Chinas most beautiful cities at its sparkling best.

Now that the summit is over, the pollution will return. If its ever going to disappear for good, then the G20 leaders who met in Hangzhou will need to follow through on a commitment they made seven years ago: to stop providing subsidies for fossil fuel development.

Together, the nations that are part of the G20 are currently responsible for more than $440 billion in fossil fuel subsidies annually and account for 74 percent of global carbon pollution. To put that into perspective, the annual total of G20 subsidies to support fossil fuels is more than four times what the entire global economy is currently investing in clean energy. Given the urgency of transitioning the global economy awayfrom fossil fuels, thats counterproductive, to say the least.

Internationally, weve seen historic climate progress lately from the agreement between the U.S. and China to limit carbon pollution to the adoption of the Paris Agreement, which China and the U.S. both formally joined last week . But while the world moves forward toward a 100 percent clean energy economy, the G20 leaders have been all talk and no walk on ending fossil-fuel subsidies for seven years now.

Thats got to stop. For our part, the Sierra Club has launched a new international campaign called Fossil-Free Finance . Our goal is to get all of the G20 countries, the World Bank, and other key international financial institutions to eliminate all fossil fuel subsidies by 2020.

This years G20 has come and gone, but this issue isnt going anywhere. Send a message to President Obama and the other G20 leaders to let them know that the only way well see blue skies everywhere, all the time, is to stop investing in the dirty fuels of the past.