Which of our habits is the worst enemy to the environment? Here's a look at some of our most common environmental transgressions, starting with the biggies. HOME ENERGY
Consumption: Nationally, about 39 percent of the energy consumed in the U.S. is used to generate electricity, making electricity the country's No. 1 source of greenhouse gas emissions.
Environmental impact: Electricity accounts for 2.5 billion tons of carbon dioxide emissions in the U.S. -- about 40 percent of the country's total CO2 emissions. Most of the energy goes to heating and cooling the home.
Saving grace: Wind energy is becoming more prevalent in the Midwest.
Alternatives: Insulate your home and buy energy-efficient appliances (look for the EnergyStar label, which indicates the product meets efficiency guidelines set by the EPA and Department of Energy). Adjusting your air conditioner or thermostat a degree makes a big difference. And if every Chicagoan replaced four light bulbs with energy-efficient compact fluorescent bulbs, it would prevent 2.6 million tons of carbon dioxide emissions, the equivalent of removing 81,164 cars from the road.
Also, electronics on standby still use electricity, so turn off computers and power strips to avoid such "phantom loads."
Sources: Environmental Protection Agency, Chicago Department of the Environment, Center for Neighborhood Technology Energy
Consumption: Americans have bought 6.9 million cars and 7.8 million light trucks (including SUVs) so far this year, and they drive about 2.6 trillion miles annually. The more than 200 million cars on American roads account for 30 percent of all cars worldwide -- though the U.S. represents less than 5 percent of the world's population.
Environmental impact: Transportation contributes a quarter of the world's carbon dioxide emissions, emitting 1.5 billion tons of CO2 annually, mostly from automobiles. The average American passenger car, driven about 12,500 miles a year, spews 11,450 pounds of carbon dioxide in a year, while the average light truck emits some 16,000 pounds annually. Cars impact the environment even when they're not moving, as paved parking lots create rainwater runoff that pollute lakes and rivers and absorb solar heat, warming the area.
Saving grace: Sales of cars that run on alternative fuels are increasing, and there are now 11.5 million such cars on American roads. There are 60 models of alternative- fuel autos on sale today, up from 12 in 2000.
Alternatives: Walk, bike or take public transit when possible. If every Chicagoan replaced one car trip a month with another mode of transportation, it would decrease carbon dioxide emissions by 1.9 million tons per year. More drastically, you can use car-sharing services or buy a hybrid or a more fuel-efficient car.
Sources: Wall Street Journal, Environmental Defense, Fueleconomy.gov, Chicago Department of Environment, Alliance of Automobile Manufacturers
Consumption: U.S. airlines transported 744.6 million passengers in 2006, pulling in $163.8 billion in revenue. Added together, passengers flew 797.4 billion miles.
Environmental impact: Air travel accounts for 2 percent of global greenhouse gas emissions, but with demand for flying rising, it is one of the fastest-growing contributors to global warming. Also, the fuel burned at high altitudes has a bigger global warming impact than fuel burned at ground level, and airplanes emit much more carbon than cars do on a per-passenger, per-mile basis.
Saving grace: Airlines have doubled fuel efficiency between 1978 and 2006 and have pledged to improve fuel economy an additional 30 percent over the next 18 years. Efforts to modernize air traffic control operations would also cut down on trip lengths.
Alternatives: Fly coach to save room and take direct flights to save fuel. Drive or take the train to your destination when possible. Forgo business trips and hold meetings through teleconferencing.
Sources: Air Transport Association, Clean Air-Cool Planet, Carbonfund.org, Tufts Climate Initiative
Consumption: Although soft drinks continue to dominate the beverage market and are responsible for most plastic beverage bottling, the staggering rise of bottled water sparked the backlash against plastic bottles. Sales of single-serving plastic water bottles more than doubled between 2002 and 2005 to almost 28 billion bottles.
Environmental impact: The 1.5 million barrels of crude oil used each year to manufacture plastic water bottles in the U.S. could fuel 100,000 cars for a year. Thousands of tons of greenhouse gases are emitted transporting bottled water around the world. Just 23 percent of all plastic bottles are recycled, meaning some 52 billion end up in landfills or littered.
Saving grace: The industry has reduced the amount of plastic in its beverage packaging by 40 percent during the past five years, and some companies such as Nestle are pushing initiatives to further lighten the plastic while others such as Coke are opening plastic-bottle recycling plants.
Alternatives: Fill a reusable bottle with filtered tap water. Recycle the plastic bottles you do accumulate. Had the 2 million tons of plastic bottles thrown in the trash in 2005 been recycled instead, 18 million barrels of oil would've been saved.
Sources: Container Recycling Institute, Earth Policy Institute
Consumption: There were more than 105 billion pieces of direct mail sent to U.S. households in 2006, accounting for half of all mail delivered by the U.S. Postal Service. That's up from 66 billion pieces of junk mail delivered in 1990.
Environmental impact: The production of junk mail in the U.S. uses 100 million trees annually, and the manufacture and disposal of it consumes more energy than 3 million cars. Some 44 percent of bulk mail gets thrown away unopened, and less than 36 percent of it is recycled.
Saving grace: Direct marketing is expected to generate $2 trillion in increased sales this year, account for 10.2 percent of total U.S. gross domestic product and employ 1.6 million people. One-third of the U.S. Postal Service's annual revenue depends on advertising mail.
Alternatives: Visit the Direct Marketing Association's Web site at the-dma.org for information on how to remove your name from mailing lists. You can pay $1 to be put on the DMA's do-not-mail list, but also contact companies directly to remove your name from their lists because not all companies go through DMA. Also, visit optoutprescreen.com to cut back on credit card and insurance offers.
Sources: Direct Marketing Association, Center for a New American Dream
Consumption: Almost 1,500 daily newspapers are published in the U.S., with a combined daily circulation of more than 53.3 million.
Environmental impact: U.S. newspapers use about 9.2 million tons of paper, consuming more than six million tons of virgin fiber every year -- more than the book, magazine and catalog sectors combined.
Making a year's worth of newspapers in the U.S. requires 105 million trees and enough energy to power 3 million homes for a year. The greenhouse gases produced by newspapers are equal to the amount produced by 4.9 million cars in a year.
Saving grace: Newspapers are the most recycled paper product, boasting a 73.4 percent recycling rate, and newsprint contains an average of 32 percent recycled fiber. Also, newsprint consumption has declined over the past 20 years, as newspapers scale back.
Alternatives: Cancel subscriptions you don't use. Recycle newspapers, magazines and catalogs. Opt out of catalogs at https://www.catalogchoice.org/signup.
Sources: Newspaper Association of America, Green Press Initiative, Environmental Defense's Papercalculator.org
Consumption: U.S. meat production is projected to exceed 90 billion pounds in 2007, helping to feed Americans who eat 220 pounds of meat per person every year.
Environmental impact: Livestock account for 18 percent of greenhouse gas emissions, including 37 percent of the world's methane (mostly from flatulent cows) and 65 percent of its nitrous oxide (mostly from cattle manure). Though carbon dioxide is a more prevalent greenhouse gas, the other two are more potent. Methane has 23 times the global warming potential of CO2 and nitrous oxide has 296 times. Livestock also are a major cause of deforestation globally as land is cleared for grazing and feed crops, which contributes to carbon dioxide emissions. Livestock consume more food than they yield.
Saving grace: Methane emissions in the U.S. have decreased 11 percent over the past 15 years, and improvements in the cattle industry, such as better-quality feed, contributed to 3 percent of that decrease.
Alternatives: Cut back on meat consumption, or pull an Alicia Silverstone and give it up completely. Get PETA's free vegetarian starter kit.
Switching from a meat to a vegan diet could save 1.5 tons of greenhouse gases annually, according to one University of Chicago study.
Sources: U.S. Department of Agriculture, Food and Agriculture Organization of the United Nations, National Cattlemen's Beef Association
Consumption: U.S. consumers used 91 billion plastic bags in 2006. In Chicago, every resident uses 208 plastic shopping bags per year. Ninety percent of all grocery bags are plastic.
Environmental impact: Twelve million barrels of oil are used each year to manufacture plastic bags for U.S. consumption, according to some estimates, yet only 7 percent of plastic bags are recycled. Worldwide, about 4 billion plastic bags end up as litter, ending up stuck in trees, oceans and in the throats of wildlife. The rest go to landfills.
Saving grace: Lightweight, low-cost and water-resistant, plastic bags are in some ways more efficient than paper bags. The manufacture of plastic bags consumes 20 to 40 percent less energy and releases 70 percent less air pollution than the making of paper bags. Also, more than 80 percent of consumers reuse plastic bags for use as trash can liners, lunch bags, picking up pet waste and more.
Alternatives: Replace plastic grocery bags with reusable bags. If everyone in the city of Chicago did, it would eliminate 601 million bags and save 4,508 tons of waste from going to a landfill. Reusablebags.com has a wide selection. Also, plastic bags are recyclable, used primarily to make composite lumber but also new bags, crates and pipes. While plastic bags are not always accepted in curbside recycling programs, some retailers have bins for plastic bag recycling. Visit plasticbagrecycling.org for more locations.
Sources: The Society of the Plastics Industry, Chicago Department of the Environment, Center for a New American Dream, International Trade Commission