Earth Day is an annual event celebrated on April 22. Worldwide, various events are held to demonstrate support for environmental protection. First celebrated in 1970, Earth Day events in more than 193 countries are now coordinated globally by the Earth Day Network.

On Earth Day 2016, the landmark Paris Agreement was signed by the United States, China, and some 120 other countries.This signing satisfied a key requirement for the entry into force of the historic draft climate protection treaty adopted by consensus of the 195 nations present at the 2015 United Nations Climate Change Conference in Paris.

In 1969 at a UNESCO Conference in San Francisco, peace activist John McConnell proposed a day to honor the Earth and the concept of peace, to first be celebrated on March 21, 1970, the first day of spring in the northern hemisphere. This day of nature’s equipoise was later sanctioned in a proclamation written by McConnell and signed by Secretary General U Thant at the United Nations. A month later a separate Earth Day was founded by United States Senator Gaylord Nelson as an environmental teach-in first held on April 22, 1970. Nelson was later awarded the Presidential Medal of Freedom award in recognition of his work. While this April 22 Earth Day was focused on the United States, an organization launched by Denis Hayes, who was the original national coordinator in 1970, took it international in 1990 and organized events in 141 nations.

Numerous communities celebrate Earth Week, an entire week of activities focused on the environmental issues that the world faces. In 2017, the March for Science occurs on Earth day (April 22, 2017) and is followed by the People’s Climate Mobilization (April 29, 2017).

The first Earth Day celebrations took place in two thousand colleges and universities, roughly ten thousand primary and secondary schools, and hundreds of communities across the United States. More importantly, it “brought 20 million Americans out into the spring sunshine for peaceful demonstrations in favor of environmental reform.” It now is observed in 192 countries, and coordinated by the nonprofit Earth Day Network, chaired by the first Earth Day 1970 organizer Denis Hayes, according to whom Earth Day is now “the largest secular holiday in the world, celebrated by more than a billion people every year.”[10] Environmental groups have sought to make Earth Day into a day of action to change human behavior and provoke policy changes.