How much CO2 is....?

According to Department of Energy data, burning a gallon of unleaded gasoline releases 19.56 lbs of CO2.

More: 10 Eco Driving Tips to Save You Fuel and Money

Based on average fuel economy stats for the entire US car fleet (about 22mpg...), switching to a car with truly high fuel-economy like the Toyota Prius will reduce the carbon footprint of your driving by 5,000 lbs a year.

More: How to Go Green: Hybrid Cars

OK, so there's a bit of abstraction in this one: The average one-way commute in the US is about 16 miles and the average fuel economy 22mpg. If you ditched your car one day a week (and worked 50 weeks in the year) you'd knock about three-quarters of a ton off your carbon emissions -- not to mention getting in better shape.

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Again, the average round trip commute in the US is 32 miles. If you've got an average US passenger car and make that trip every workday with four people in the car instead of driving alone, you've reduced you've each reduced your carbon footprint by nearly 2.75 tons.

More: 6 Carpool Tips You Need to Know

Though the exact amount of CO2 per kilowatt-hour of electricity varies widely from state to state, averaged over the whole nation, 1 kWh emits 1.297 lbs of CO2. The average amount of electricity used per month in the US is 920 kWh.

More: How to Go Green: Electricity

While it is good to unplug your electronic chargers when not in use, due to the minute amount of electricity they draw, compared to other aspects of your life, this is pretty much chump change: Over an entire year only 11 lbs of your total carbon footprint.

More: Save Energy by Avoiding Phantom Power

According to data from Carbon Fund, each short haul flight creates .528 lbs of CO2 per passenger mile.

More: Greener Flying: Not All Flights Are Created Equal

Again using Carbon Fund data, long-distance train travel emits 0.42 lbs of CO2 per passenger mile -- 210 lbs for a 500 mile trip, and a saving of 54 lbs of CO2. If you had taken the bus, you would have saved 174 lbs compared to flying.

More: Planes, Trains, Automobiles (and Buses): Which is the Greenest Way to Travel Long Distance in the US?

Reducing the amount of meat in your diet is one of the greatest things you can do to lower your personal carbon footprint. In fact, eating a lacto-ovo vegetarian diet for one year results in a carbon footprint nearly 1 ton lower than you meat-eating neighbors.

More: Try a Weekday Vegetarian Diet : Eat Green Food Without Taking the Plunge

The clothes dryer is one of the most energy-sucking appliances in your house. Air-drying all your clothes for a year can reduce your personal carbon footprint by a bit over 1400 pounds.

More: Hang Your Laundry Out to Dry