April 22 marks the anniversary of what many consider the birth of the modern environmental movement in 1970. Founder Gaylord Nelson, then a U.S. senator from Wisconsin, was inspired by the student antiwar movement and the groundswell of protest generated by Rachel Carson’s book The Silent Spring. He wanted to put environmental protection on the national political agenda. On April 22, 1970, 20 million Americans demonstrated for a healthy, sustainable environment in massive coast-to-coast rallies.

Today, the Earth Day Network works with over 22,000 partners in 192 countries to broaden, diversify and mobilize the environmental movement. More than 1 billion people now participate in Earth Day activities; here’s how you can join them:

A Billion Acts of Green: the Largest Environmental Project on the Planet. Greenrock is encouraging the community to plan their own green event for Earth Day by registering on its website www.greenrock.org. Greenrock will link your event to the Earth Day Network Billion Acts of Green project. The worldwide goal is to register one billion acts of green before the Rio+20 Summit in June 2012. Companies, school groups, churches, youth groups, families and individuals could plant trees, invite a speaker, carpool, visit a farm, pledge to use less water—the possibilities are up to you.

To register your Earth Day event, visit www.greenrock.org.

Need ideas for your Billion Acts of Green pledge? Try one of these:

Never buy bottled water again: Trade your bottled-water habit for an at-home filtering pitcher and you can help make a dent in the 1.5 million barrels of oil used to make plastic water bottles each year; pair it with a reusable bottle (like one made of glass, aluminum or recycled plastic), and you’ll always be prepared to tackle your thirst.

Brew your own Fair-Trade coffee: Carrying your own coffee in an insulated travel mug helps you reduce waste from cardboard cups and carrying sleeves—which are thrown away at a staggering rate of 58 billion each year. For greener at-home brewing, choose a fair trade blend that supports farmers; add organic milk instead of artificial creamers; and try a French press (instead of a traditional brewer) to save electricity.

Remember your reusable bags: With more than 1 million plastic bags ending up in the trash every minute, taking reusable bags to the store is one of the easiest and most effective ways to reduce your carbon footprint—but the hardest part about using them is simply remembering to take them with you.

Cut back on paper towels: Invest in a few cotton cloths and some fabric napkins; then drop them in the wash when you run a load of laundry. Using cloth alternatives is just as easy as using paper versions, and you only need to buy them once—plus you can help eliminate the 3,000 tons of paper towels that end up in landfills every day.

Buy your fruit and vegetables directly from a farmer: Head to the farmer’s market on Saturday mornings or just visit one of the many roadside stands for the best fresh, local fruits and vegetables.

Become a weekend vegetarian: Cutting meat out of your diet just two days a week can decrease your carbon footprint by about 1/3 of a ton, and coming up with meat-free meals for Saturday and Sunday isn’t as hard as it sounds. Try pancakes and fruit for breakfast; fresh salads or roasted vegetable sandwiches for lunch; and veggie pizza, bean soups and creamy risottos for dinner.

Eliminate phantom power: Use power strips to turn off all your appliances at once. Put your television, DVD player, game system and stereo on a timer so they automatically shut off overnight, and invest in chargers that stop drawing current when the device’s battery is full. You could cut your energy bill by as much as 10 percent annually—without lifting a finger.

Replace your lightbulbs: Despite the jokes, it takes only one person to change a lightbulb, and since compact fluorescent lights last longer than traditional bulbs, you’ll be saving time for years down the road while cutting your energy use by as much as 80 percent.