U.N. World Environment Day 2016 is Sunday. The green holiday, which is celebrated every June 5, is the U.N.’s “most important day for encouraging worldwide awareness and action for the protection of our environment,” according to the group’s website

Listed below are a few quick facts and ways to celebrate the day and to contribute toward improving the environment as climate change becomes an increasingly dire problem.

1. The U.N. started the day decades ago and it calls for action — World Environment Day was founded in 1974 and has since expanded. “Since it began in 1974, it has grown to become a global platform for public outreach that is widely celebrated in over 100 countries,” the U.N. website reads.

It encourages action among folks worldwide, the World Environment Day (WED) site calls it “the ‘people’s day’ for doing something to take care of the Earth or become an agent of change. That ‘something’ can be focused locally, nationally or globally; it can be a solo action or involve a crowd — everyone is free to choose.”

2. There’s a theme — World Environment Day has a theme each year, and in 2016 it’s “Go Wild for Life,” which is directly related to the host country in fact No. 3.

3. This year’s host is Angola — One nation hosts World Environment Day every year, and in 2016 that country is Angola. Angola is hosting because it has particular interest in preserving its wildlife and rebuilding its elephant population threatened by poaching.

“Angola is delighted to host World Environment Day, which will focus on an issue close to our hearts,” said Angolan Environment Minister Maria de Fatima Jardim in December. “The illegal wildlife trade, particularly the trade in ivory and rhino horn, is a major problem across our continent. By hosting this day of celebration and awareness-raising, we aim to send a clear message that such practices will soon be eradicated.” 

4. The need for change could be urgent — The U.N. reported last year that by the year 2050, humankind would need three planets to sustain itself at its current rates for population growth and consumption.

5. You can register your event — World Environment Day is aimed at getting people involved, and to that end, the U.N. allows people worldwide to register what they’re doing Sunday. The U.N. then adds the event to a list shared with people worldwide. Last year there were some 2,861 registered activities with 1.26 million people participating worldwide, according to the U.N.

Check out how to register here and check out the slate of events here. In the U.S., for instance, there are events at the Forth Worth Museum of Science and History and the United Nations Environment Program’s Regional Office for North America.