This Tuesday marks the 40th observance of World Environment Day, a global day for environmental awareness organized by the United Nations in 1972.

The theme of this year's World Environment Day is "Green Economy: Does it include you?" According to the United Nations Environment Programme, a green economy, put simply, is "one which is low carbon, resource efficient and socially inclusive."

This year, the UNEP is challenging individuals to take up an activity that will make them a part of the green economy, and share their efforts with the world. Activities will be judged in one of five categories, with winners receiving a new vehicle from Kia.

The U.N. produced a green economy report in 2011 which "challenges the myth that there is a trade-off between the economy and the environment," explained a press release. The report, according to the U.N., "confirms that an investment of two percent of global GDP across 10 key sectors is what is required to kickstart a shift from the current brown, polluting and inefficient economy to a green one."

2011 was also a record year for global carbon dioxide emissions, with China leading the world in a 3.2 percent rise over the previous year's emissions levels. Fatih Birol, the International Energy Agency's chief economist, told Reuters, "When I look at this data, the trend is perfectly in line with a temperature increase of 6 degrees Celsius (by 2050), which would have devastating consequences for the planet."

Click here for a list of WED activities across the U.S. and find tips below for green activities you can enjoy with children on World Environment Day, Earth Day and every other day of the year. Scroll down for videos.

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  • 1. Take A Hike

    Even in the most urban parts of America, natural beauty can be found just a few miles from home. Take your child on a nature walk, or a hike on a nearby trail. Keep an eye out for exotic birds and insects (just remember not to touch!) and make sure to point out exceptionally beautiful plants. Find the nearest nature reserve or trail near you by checking out <a href="" target="_hplink"></a>, <a href="" target="_hplink"></a>, or <a href="" target="_hplink">the Sierra Club website</a>. Before you go, make sure to read <a href="" target="_hplink">REI's advice for hiking with kids</a>. Don't forget sunscreen, a hat, and reusable water bottles!

  • 2. Make Earth-Friendly Treats And Picnic

    What better way to celebrate World Environment Day with your kid than to spend it in the kitchen?  The night before, make <a href="" target="_hplink">granola</a> with your child so they have a crunchy, earthy, homemade breakfast to look forward to in the morning. For lunch, put together some colorful salads made with local, organic vegetables and fruits. Talk about the different tastes, textures, and colors that come naturally from these foods, and why it is so important to eat things that come straight from the ground instead of a factory. <a href="" target="_hplink">This list from</a> is a good place to get some ideas. For a protein side, <a href="" target="_hplink">have fun with cage free hard boiled eggs</a>. Extra points for organic and all-natural ingredients! Now comes the best part: dessert. Baking cakes, cookies, and cupcakes gives you the chance to show your child how sweet World Environment Day can really be. Check out <a href="" target="_hplink">Earth Day Globe Cookies</a> from Family Corner,<a href="" target="_hplink"> Bug Mountain Cake</a> from Family Fun, and this creative concept from<a href="" target="_hplink"> Dollhouse Bake Shoppe for Fruit Tree Cupcakes</a>. For extra fun, pack up your meal and make it a picnic. Check out the <a href="" target="_hplink">Nature Conservancy's plan to Picnic for the Planet</a> and participate in an event. <em><a href="" target="_hplink">Flickr image courtesy of zestycarl</a></em>

  • 3. Read A Book

    Sometimes, the best way to teach your child is just to read a book with them. Children's books often carry beautiful messages about planet Earth in a very understandable way. Pick up some<a href="" target="_hplink"> green kids' books at Barnes & Noble</a>, or order them online through <a href="" target="_hplink">Amazon</a>. <br> Here are some of our favorite children's reads: <br> <em><a href="" target="_hplink">Olivia's Birds: Saving the Gulf</a></em> by Olivia Bouler: This collection of drawings an 11-year old girl did in the aftermath of the 2011 Gulf Oil Spill is inspirational, and awe-inspiring -- with this collection, Olivia raised $175,000 for the recovery effort. <br> <em><a href="" target="_hplink">The Lorax</a></em> by Dr. Seuss: This environmentally aware classic was published in 1971, just one year after the Earth Day movement began! <br> <em><a href="" target="_hplink">The Magic School Bus and the Climate Challenge</a></em> by Joanna Cole: Miss Frizzle is the queen of science fun, and this Earth-friendly adventure is no exception. <br> <em><a href="" target="_hplink">Earth Day-- Hooray!</a></em> by Stuart J. Murphy: Not only does this teach kids about the benefits of recycling, but helps them with math along the way. <br> <em><a href="" target="_hplink">The Earth and I</a></em> by Frank Asch: If "The Giving Tree" has a warm place in your heart, you and your child will want to read this book about the special relationship humans have with nature. <br> <em><a href="" target="_hplink">The Earth Book</a></em> by Todd Parr: Made with recycled materials and nontoxic soy ink, this book truly practices what it preaches. <br> <em><a href="ttp://" target="_hplink">Every Minute on Earth</a></em> by Steve Murrie: For the children of Trivia Night royalty, this book is full of great Earth factoids.

  • 4. Plant Something

    Although it may take longer than one day to see results, planting fruits, vegetables, flowers, or herbs can thrill children, and teach them how we can all contribute to the natural beauty of the world. If you are already a gardener, <a href="" target="_hplink">take your kids outside</a> and have them help you with your plants. Let them weed, water, or actually plant bulbs and they will feel super important and proud. Here are the <a href="" target="_hplink">National Wildlife Federation's tips for gardening with kids</a>, just to make things a little easier. Not enough backyard space for serious planting? Potted plants brighten up a room and give your child a chance to see his or her project bloom on a daily basis. <a href="" target="_hplink">Web Ecoist's list of hard-to-kill houseplants</a> could be a good place to start for the easily distracted. If your child is one to nurture and love a plant, <a href="" target="_hplink">potted herbs are always fun</a>.

  • 5. Build A Bird Feeder

    Building a bird feeder is a classic childhood activity that connects kids to the world around them. Check out <a href="" target="_hplink">HGTV's different types of bird feeders</a> you can make with your kid out of recycled materials. Or, of course, you can always just go the <a href="" target="_hplink">peanut butter and pine cone route</a>! <em><a href="" target="_hplink">Flickr image courtesy of USFS Region 5</a></em>

  • 6. Go See The Animals

    One of the best parts about World Environment Day is experiencing the natural wonder in our communities. For a fun day trip, take your kids to the local zoo, aquarium, or botanical gardens to see what the world has to offer. Find a zoo or aquarium near you through the <a href="" target="_hplink">Association of Zoos and Aquariums website</a>. You may even live near one of Parents Magazine's <a href="" target="_hplink">Top 10 Zoos</a> or <a href="" target="_hplink">Top 10 Aquariums</a> for kids! Check out your local zoo/aquarium website to find out more. Are your kids too young for a zoo, or would just prefer to see some flora? You can also find a nearby arboretum or botanical gardens through <a href="" target="_hplink">the Better Homes and Gardens locator</a>. Or just pack up a picnic and head to your local park!

  • 7. Play The Recycling Game

    Here at HuffPost Green, we believe that anything that can be turned into a game, should be. By making recycling fun, your kids will better understand the concept from a young age, and will be excited to participate when it comes time to separate your glass and paper. If your kids enjoy playing on the computer, have them check out these <a href="" target="_hplink">recycling games on the BBC website</a> and <a href="" target="_hplink"></a>. <a href="" target="_hplink">This packet from the California Energy Commission</a> has loads of crafts, facts, and games focused on recycling that you and your child can look through together. Have a large group (or at least 2+ kids) and want to involve them all? Play this recycling game, and actually sort your waste in the process: 1. Split the kids into two teams, or have each child play on their own. 2. Give them a pile of mixed recycled goods: plastics, paper, aluminum cans, or anything else that is safe for a child to toss. 3. Set up 3 bins near each team labeled "paper" "plastic" and "aluminum" 4. On the count of three, see which team can sort the pile into the appropriate bins first. Whoever wins gets a World Environment Day cookie!

  • 8. Reuse Old Clothes

    Since kids cycle through clothes fast, teaching them new uses for old items is a great World Environment Day activity. Have them transform <a href="" target="_hplink">an old t-shirt into a fun pillow</a>, or <a href="" target="_hplink">make sock puppets</a> that can be used to perform a play. As long as you use non-toxic, all natural materials, <a href="" target="_hplink">tye-dyeing is fun</a> any day of the year! For an added splash, use different hues of greens. <em><a href="" target="_hplink">Flickr image courtesy of Vancour</a></em>

  • 9. Play In The Dark

    Kids love a good mystery, and playing in a dark room can help explain the concept of power saving. Have them play hide and seek or marco polo in a room with the lights off, or gather in the closet and tell a (not too) scary story. Show them how much fun can be had without using any extra power. Just make sure to put any sharp or dangerous objects away before you shut off the lights!

  • 10. Make A Solar Oven

    Explaining the concept of renewable energy to kids can be tricky, which is why making a solar oven is such a great World Environment Day activity. PBS kids has a great <a href="" target="_hplink">step-by-step solar oven guide</a>, or check out this easy <a href="" target="_hplink">Home Training Tools method</a>. They even have <a href="" target="_hplink">some tasty recipes</a> for you to make in your new cooker! <em><a href="" target="_hplink">Flickr image courtesy of frankenstoen</a></em>

Be sure to check out these World Environment Day messages from Giselle Bündchen and Ian Somerhalder below. Find more celebrity WED videos here.

WATCH a World Environment Day message from Giselle Bündchen:

WATCH Ian Somerhalder on World Environment Day and working with Giselle and Don Cheadle: