Global Warming: It's Not Just Carbon Dioxide
About 80 percent of the United States’ total global warming
pollution consists of carbon dioxide (CO2) generated largely by the
burning of fossil fuels. But other heat-trapping gases could be responsible for
40 percent of the warming observed since the mid-1800s. Fortunately, many of
the strategies we can adopt to reduce CO2 emissions will also reduce
non-CO2 emissions.
Methane emissions—the second-largest contributor to global warming—have more than doubled since the 1700s. The main sources of methane, which traps 23 times as much heat as CO2 but remains in the atmosphere for 12 years (compared with hundreds to thousands of years for CO2), are coal and natural gas production, landfill waste, and CAFOs, or confined animal feeding operations, which generate large, concentrated amounts of manure. To reduce methane:
- Compost food waste and recycle.
- Consume fewer meat and dairy products—or choose products from pasture-raised animals (which produce less concentrated manure).
- Purchase “green” power from your utility or renewable energy credits from a reputable third party (see the Related Resources).
Ground-level ozone, a major component of smog, which has increased three-fold in the Northern Hemisphere over the last century, is formed when nitrogen oxides, produced by the burning of fossil fuels, and volatile organic compounds (VOCs), produced from paints and solvents, chemically react in the presence of heat and sunlight. To reduce ozone:
- Choose a car with the highest fuel economy and lowest emissions you can afford.
- Purchase green power or renewable electricity credits.
- Choose low- or no-VOC products.
Nitrous oxide, generated during fertilizer production (fertilizer is made from natural gas) and from fossil fuel combustion in power plants and vehicles, traps almost 300 times as much heat as CO2 and stays in the atmosphere for around 120 years. To reduce nitrous oxide:
- Choose organic produce (grown without chemical fertilizers) and meat and dairy products from animals raised on pasture or organic feed.
- Buy a fuel-efficient vehicle.
- Purchase green power or renewable electricity credits.
Fluorinated gases (hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride), which are used as refrigerants and aerosol propellants and in foam production, comprise only 2 percent of global warming emissions but trap heat far more effectively than CO2, and some last much longer. To reduce these emissions:
- Minimize your use of air conditioning.
- Get rid of a second refrigerator or separate freezer that doesn’t get much use.
- Dispose of air conditioners and refrigerators properly to avoid refrigerant leaks.
- Avoid foam- or aerosol-based products when possible.
