The Zero-Emissions Challenge, Part 6: Other Sources of Carbon Emissions
Hobbies, too, produce CO2. One of mine is building N-scale models in wood.
The carbon calculators consider one other source of carbon emissions: aircraft travel. A single round-trip, cross-country flight produces half the Kyoto protocol's 11,000 pound per person annual allowance of CO2. But aircraft trips are straightforward: you either make them or you don't. And whether we fly is not always under our control. A friend of mine who jets all over the country for his job was shocked at the impact his employment had on the environment. He said he'd approach his boss to suggest that more of his work be done by video conference. There are solutions, but we may not have the authority to implement them.
Personally, I average one flight a year. I plan to try to cut that back to one flight every three years, for an average annual CO2 footprint of 1,980.
But what about sources of carbon emissions not considered by the various carbon calculators? Food, for example, generates emissions during production, packaging, and transportation. In 1994, in energy consumption alone, the food industry produced 24.4 million metric tons of carbon emissions, or 671 pounds of CO2 per person annually.* That doesn't include emissions from fertilizer (estmated at 30% of the energy required for crop and feed production), rumination (of cattle), waste, refrigeration and freezing, and plastic packaging.
Statistics for emissions per pound of food from various aspects of production are very difficult to find and sometmes contradictory. Some estmates claim that meat produces 10 or 12 times as much greenhouse gas as veggies, but the base statistics on which these estimates are based appear to be disputed. Decisionmaking is also complicated by the fact that properly-managed agriculture can actually reduce carbon in the atmosphere. A DOE report suggests that potential reductions in emissions from agriculture could actually exceed its total energy emissions— but details are scarce.
Treehugger estimates that between production, transportation, and cooking, a fast-food burger causes about 6.5 pounds of CO2 per burger! The average American eats 3 burgers a week, adding 1,014 pounds of CO2— 1/10 of the annual allowance. But the article doesn't say how it arrived at that number. Many of the common assumptions about meat production are out of date, incorrect, and based on factory beef farming. (Because cows are ruminants, they produce far more greenhouse gas than pork or chicken, and therefore even accurate emissions projections for beef are not valid for other meat sources.)
We can make some generalizations, however. At 28,000 BTU/ton-mile, air freight is the worst offender, producing about 2 pounds of CO2 per pound of food carried a thousand miles. So fresh fruit from New Zealand adds about 20 pounds of CO2 for every pound of fruit— if they're eaten in Los Angeles at the airport.
Transportation by truck adds to the CO2 footprint. At 3,400 BTU/ton-mile, food trucked an average of 1,500 miles to your table adds 4/10 of a pound of CO2 per pound of food. Given that the average American eats well over a ton of food each year, eating supermarket food could produce 800 pounds of CO2 annually just in transportation.
Clearly local food more responsible than food shipped in from far away, and responsible farming practices (like organic farming) are better than factory farms. All things being equal, a vegetarian diet is better for the environment than a meat diet. But how does meat produced locally using environmentally-friendly practices stack up against soy grown on factory farms in another state? If the necessary information exists, I can't find it.
Most of us have hobbies that require supplies trucked in from far away, either to local stores or by mail order. This transportation adds a footprint based on the weight of what we use. (My wife's crocheting supplies weigh less than what I buy for reloading ammunition.) Golfing has a footprint, as does any production of plastics (surfboards, polyester clothing, styrene for building models, etc.).
In other words, each of us has a base carbon footprint that's hard to calculate— and that isn't taken into consideration by any carbon calculator I have yet seen. My guess is, it averages 1,200 to 2,000 pounds of CO2 per person per year. We can reduce it or offset it, but it's tough to eliminate completely.
* The chart says carbon emissions, and is presumed to say what it means. Carbon emissions are divided by 3/11 to calculate CO2 equivalence.
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