Some 20 million people across the US took part in the first Earth Day—50 years ago. Here’s a look back on the 50 years of action since that day in 1970: https://natwild.life/EarthDay50 

1970s: Environmental Protection Agency is established, followed by landmark laws such as the Clean Water Act and Endangered Species Act.

1980s: Discovery of a giant hole in the ozone leads to action phasing out chemicals that cause ozone depletion.

1990s: Earth Day goes global with a focus on global production of toxic waste and reducing fossil fuels.

2000s: International cooperation resulted in such treaties as the Stockholm Convention and the Kyoto Protocol, with the aim of reducing chemicals and greenhouse gas emissions.

2010s: 174 nations and the EU sign on to the Paris Agreement—committing to slow global warming.

2020s: Earth Day celebrates 50 years, but the work is just beginning.“Problems have snowballed so our efforts must, too,” says @EarthDayNetwork president Kathleen Rogers.