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.
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 Chicago did so, it would eliminate 601 million bags and save 4,508 tons of waste from going to a landfill. Chicago-based 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 accepted in Chicago's curbside recycling programs, some retailers such as Jewel-Osco 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