• Choose an efficient vehicle. The difference between a car that gets 20 MPG and one that gets 30 MPG not only amounts to savings at the gas pump. Each gallon of gasoline burned creates 20 pounds of carbon dioxide, so with a car that gets 10 more mpg, you could reduce your greenhouse gas emissions by about 2,500 pounds per year. You could also consider purchasing a gas-electric hybrid car.
• Remove extra weight in the trunk to increase your car’s fuel efficiency. The heavier the car, the harder the engine has to work and the more fuel it consumes. The EPA estimates that for every extra 100 pounds your car carries, it loses 2% in fuel economy.
• Make sure that your tires are properly inflated. To find out how much air should be in your tires, check your owners' manual. The EPA estimates that properly inflating your tires can increase fuel efficiency by 3% — and reduce carbon dioxide emissions by about 275 pounds per year.

• Set your refrigerator temperature at 3 to 5 degrees Celsius (38 to 42 degrees Fahrenheit)
• Set your freezer between -18 and -15 degrees Celsius (0 and 5 degrees Fahrenheit).
• Wash only full loads in your dish and clothes washers, and air dry when possible. Unplug the appliances when you’re not using them.

Not all seafood is created equal — but you can help keep the Earth’s oceans and rivers healthy and balanced by choosing to eat fish that has been sustainably sourced. Your choices can help shift demand away from unsustainably harvested stocks and put pressure on suppliers to improve practices so that all fisheries are better managed.

How can you tell which products are sustainably sourced? Here are several ways to find out:

• Check out the Marine Stewardship Council, which provides an online sustainable seafood product finder.
• Visit the Monterey Bay Aquarium’s Seafood Watch website, where you can download and print a pocket-sized guide, browse sustainable seafood recipes or sign up for a bimonthly e-newsletter for the latest news about sustainable seafood recommendations.
• To eat sushi guilt-free, consider “Sustainable Sushi,” a pocket-sized book chronicling sustainable sushi sources and a website with a sustainable sushi restaurant map.

Eating meat-free just one day a week can reduce your impact on the planet. It’s easy to not think about the environment when you’re biting into a juicy hamburger, but consider these costs:

• The production of one burger requires about 1,850 gallons of water — the bulk of which is used to grow grain for cattle feed.
• Because cattle ranching requires large tracts of land, producers frequently clear-cut tropical forests to provide pastures for their herds. Extensive cattle ranching accounts for 80% of the Amazon's deforestation. By one estimate, for every head of cattle, two football fields of rainforest have been destroyed.

If everyone in the United States ate just one more vegetarian meal a week for one year, more than 36,000 trillion gallons of water would be saved. Other protein-rich foods like black beans, chickpeas and tempeh make tasty substitute burgers.

We’re all guilty of throwing away food at some point — in fact, roughly one-third of the food produced in the world for human consumption every year gets lost or wasted. And once that half-sandwich or week-old lasagna is in the trash can, it’s easy to forget about the environmental impacts.

But wasted food contributes billions of tons of greenhouse gases. By the time you step into a grocery store, nearly 3.3 billion tons of emissions are already on their way to the atmosphere due to the production, processing and transportation of food that is eventually wasted. Then, in the landfill, decomposing organic waste generates methane, a potent greenhouse gas that traps 23 times more heat in the atmosphere than carbon dioxide. More than 20% of all methane emissions come from landfills.

Wasted food also means wasted water — about 25% of all fresh water consumed annually in the United States is associated with discarded food. Water losses through food waste occur at home, but they also happen through inefficient food harvesting, transport, distribution, processing and storage methods. In the U.S. alone, we throw away or waste about 30% of our food — or about 11 trillion gallons of irrigation water. Scientists estimate that we could reduce global water consumption by more than one-third if we could eliminate food loss and waste. According to the World Resources Institute, inside the roughly 1.3 billion tons of food lost or wasted every year worldwide is 45 trillion gallons of water.

The good news is that reducing food waste is very easy — it just takes a little extra planning. A number of organizations have produced lists of tips, including the UN Environment Programme and the Food and Agriculture Organization, who paired up and started a global campaign, Think Eat Save. A few simple suggestions:

• Before you go shopping, plan your meals; inventory your fridge and pantry; and make (and stick to) a list.
• Prepare reasonable serving sizes.
• Freeze or repurpose leftovers.
• Preserve extra produce through canning, freezing, pickling or drying.

Composting is nature’s way of recycling. Food scraps are full of energy to harvest and — even if you live in a yardless urban apartment — you can keep them out of the trash bin and out of landfills, where they would otherwise release methane, a potent greenhouse gas.

Even a fire escape or balcony can provide enough space for a small bin, pail or bucket to toss food scraps into. You can purchase these online or make your own indoor bin. Worm composting can also be done indoors. This method uses red worms to transform food scraps into vermicompost.

Or you can simply freeze your food scraps and find a compost collection site. Many farmer’s markets and community gardens will also do the dirty work for you. A growing number of curbside composting programs are making urban composting easier, such as in San Francisco, Portland and Washington, D.C.

If you have the yard space, here’s a helpful DIY composting guide. No garden to use the compost in? Consider using the compost in your houseplants, offering it to neighbors with gardens, or donating it to a school, community garden or farm.

Your responsible consumption will reduce the demand for endangered species. For instance, when traveling, avoid purchasing wild animal products including ivory, meat, skins and traditional medicines. Buy local handicrafts instead. Ask questions before you buy souvenirs to make sure your purchases are legally sourced. When in doubt, do not buy anything that contains wildlife parts.  

Learn about CI’s partner, the Coalition Against Wildlife Trafficking, that is trying to reduce consumer demand for illegally-traded wildlife and goods by raising awareness of the impacts the trade has on natural resources and human well-being. Visit their website to find resources and follow the latest reports about the illegal wildlife trafficking trade. 

With advances in transportation and information technology, even the most remote places on Earth are within reach. In fact, tourism is now the world's largest industry, with ecotourism the fastest growing segment in many parts of the world, including sub-Saharan Africa, Indonesia and the Greater Mekong region. 

Of course, traveling and the things that go with it — flights, hotel rooms, cab rides and rental cars — can mean significant damage to the environment and the biodiversity it holds. So the next time you go on vacation or take a business trip, consider ways you can cut down on carbon emissions:

• Choose accredited ecotourism companies and destinations. The International Ecotourism Society (TIES) provides an online directory for easy searching of sustainably-certified hotels, B&Bs and lodges.
• Fly direct when possible (takeoff is the most fuel-intensive segment of any flight) or take a train.
• If you do fly, take advantage of airlines that offer programs to reduce your impact. United Airlines, which has been a CI partner since 1998, allows passengers to offset the carbon footprint associated with their air travel and support CI’s Alto Mayo Forest Carbon Project in Northern Peru. 
• Use local and public transport whenever possible. If you have to rent a car, ask for a hybrid or electric vehicle. 
• Stay in hotels that offer environmentally-friendly properties and programs. CI worked with Starwood Hotels & Resorts on setting and achieving environmental performance goals, and the company has committed to reducing energy consumption by 30% and water consumption by 20% by the year 2020. CI also worked with Marriott International on a sustainability strategy to minimize the company’s carbon footprint. No matter where you stay, at check-in, request that your sheets and towels are not changed unless left on the floor and ask whether your recyclables are properly recycled. Make sure that heating/cooling is turned off when you’re not in the room. At check-out, leave a comment card to let the management know whether your requests were satisfied and praise successful efforts to be green.

Share your expertise to help implement sustainable development projects around the world. Here are a few accredited international volunteering organizations that combine travel with conservation:

• Cross-Cultural Solutions
• International Volunteer HQ
• GoEco

Or stay closer to home and help make your community greener. The Arbor Day Foundation offers an easy-to-use database for locating tree planting and conservation-oriented volunteer opportunities. Every small and large step, from picking up trash to starting a community garden, will make a difference. And don’t just save your good deeds for Earth Day. The planet needs volunteers all year.