The Carbon Footprint & Global Warming Explained (Part 1)
First came organic. Then came fair trade. Now makers of everything from milk to jackets to cars are starting to tally up the carbon footprints of their products. That’s the amount of carbon dioxide and other greenhouse gases that get coughed into the air when the goods are made, shipped and stored, and then used by consumers.
In the Gelsi household, reducing their carbon footprint is a family affair — they even wrote a musical about it. MarketWatch reporter Steve Gelsi offers tips for saving the environment and saving money while doing so.
So far, these efforts raise as many questions as they answer. Different companies are counting their products’ carbon footprints differently, making it all but impossible for shoppers to compare goods. And even if consumers come to understand the numbers, they might not like what they find out.
For instance, many products’ global-warming impact depends less on how they’re made than on how they’re used. That means the easiest way to cut carbon emissions may be to buy less of a product or use it in a way that’s less convenient.
So, what are the carbon footprints of some of the common products we use? How are they calculated? And what surprises do they hold? What follows is a look at six everyday items — cars, shoes, laundry detergent, clothing, milk and beer — and the numbers that go with them.
But first, here’s a number that will help you put all those carbon footprints in perspective. The U.S. emits the equivalent of about 118 pounds of carbon dioxide per resident every day, a figure that includes emissions from industry. Annually, that’s nearly 20 metric tons per American — about five times the number per citizen of the world at large, according to the International Energy Agency.
The simplest statistic in the carbon-footprinting game may be this: For every mile it travels, the average car in the U.S. emits about one pound of carbon dioxide. Given typical driving distances and fuel-economy numbers, that translates into about five tons of carbon dioxide per car per year.
A study by the University of Michigan’s Center for Sustainable Systems found that, over its expected 120,000-mile life, an American-made midsize sedan emits the equivalent of about 63 tons of carbon dioxide. That number includes all emissions, from the making of the car’s raw materials, such as steel and plastic, through the shredding of the car once it’s junked.
The vast majority of those emissions — 86% — came from the car’s fuel use, the study found. Just 4% of emissions came from making and assembling the car. That means consumers can lower their footprint by buying a car with better fuel economy.
Sometimes, the differences between models can be substantial. For one overview of how cars stack up, consider a new computer model paid for by Toyota Motor Corp. that computes the lifetime carbon footprints of about 400 auto models from multiple manufacturers.
To narrow things down, consider a handful of Toyota’s own models. The Prius, a hybrid gasoline-and-electric car that averages 42 miles per gallon, has a lifetime carbon footprint of 44 metric tons, according to the updated computer model done for Toyota by Kreider & Associates, a consultant based in Boulder, Colo. The Corolla, a small sedan with a conventional gasoline engine rated at 29 miles per gallon, has a footprint of 64 tons. The Camry, a larger car rated at 23 miles per gallon, has a footprint of 95 tons. And the 4Runner, an SUV rated at 16 miles per gallon, has a footprint of 118 tons.
Gregory Keoleian, co-director of the Michigan center, says he used to advise people that the best way to minimize the carbon footprint of their driving was to keep their car as long as possible, since junking a car and manufacturing a new one produces pollution. But that was before hybrids hit the market and offered markedly better fuel economy. Now, he says, scrapping an old car in favor of a new model makes lots of sense.
The introduction of the hybrid “changes the whole dynamic,” Mr. Keoleian says. “Then, you replace.”
You may think you’re at one with nature going for a walk in the woods in your sturdy hiking boots. But those boots pack a lot of carbon. The big reason: the leather.
Timberland Co., a Stratham, N.H., shoe company with an outdoorsy image, has assessed the carbon footprint of about 40 of the shoe models it currently sells. The results range from about 22 pounds to 220 pounds per pair. Each of the shoes that has been carbon-footprinted comes with a label assessing its greenhouse-gas score on a scale of zero, which is best, to 10, which is worst.
Flip-flops tend to have footprints of 22 pounds to 44 pounds, says Pete Girard, senior analyst for environmental stewardship at Timberland. Shoes typically range from 66 pounds to 132 pounds. Hiking boots typically pack between 154 and 198 pounds, Mr. Girard says.
Though Timberland produces many of its shoes in Asia and sells them in the U.S., it has found that transportation typically accounts for less than 5% of the carbon footprint. By far the biggest contributor is the shoe’s raw material. “For most Timberland shoes,” says Betsy Blaisdell, Timberland’s manager for environmental stewardship, “leather really drives the score.”
The average dairy cow produces, every year, an amount of greenhouse gas equivalent to four tons of carbon dioxide, according to U.S. government figures. Most of that comes not from carbon dioxide, in fact, but from a more-potent greenhouse gas: methane.
The cow’s impact on the atmosphere is due largely to a process known scientifically as “enteric fermentation” — and colloquially as burping. A cow’s multiple stomachs make it particularly efficient at transforming feed into bovine products: meat, milk and hide. But all that churning also produces lots of methane — a greenhouse gas that, pound for pound, is 25 times as damaging to the atmosphere as carbon dioxide, according to the United Nations. Converting those methane emissions into a carbon-dioxide-equivalent number is one step in calculating the cow’s carbon footprint.
Take Timberland’s Winter Park Slip On Boot. They’re casual boots — not as heavy as hiking boots — but their uppers are all leather. Their footprint sits in the middle of the Timberland range, at 121 pounds per pair. Of that total, 8.5 pounds comes from the electricity used to make the boots at Timberland’s factory in China’s Guangdong Province. The remaining 112.5 pounds comes from the raw materials used to make the shoe: rubber for the outsole; ethyl vinyl acetate, or EVA, for the midsole; and, most of all, leather for the upper.
To come up with these numbers, Timberland first gets data from the factory on the amount of electricity the factory uses in a given period. Dividing that by the number of shoes the factory produces in that period yields a per-shoe energy-consumption figure.
Timberland then checks those figures against tables that list average carbon-dioxide emissions per unit of energy produced. The tables are tailored to the specific power-plant fuel mix in the area where the factory sits. In China, which makes much of its power by burning coal, the carbon hit is greater than in, say, France, which makes most of its electricity with nuclear power.
The harder part for Timberland is figuring out the emissions that come from the part of the process it doesn’t control: the production of the raw materials before they get to the Timberland factory. Timberland gets that information from the databases of “life-cycle analysis” consultants, who put together tables showing the environmental impacts of producing given amounts of various materials, from rubber to polyester to leather.
Timberland’s carbon-footprint calculations have prompted spats with some of Timberland’s leather suppliers, Ms. Blaisdell says. They argue the carbon hit from a cow should fall not on their ledger, but on the ledger of beef producers. The leather producers reason that cows are grown mainly for meat, with leather as a byproduct, so that growing leather doesn’t yield any emissions beyond those that would have occurred anyway.
But Timberland has determined that 7% of the financial value of a cow lies in its leather. And life-cycle-analysis guidelines used by Timberland say the company should apply that percentage to compute the share of a cow’s total emissions attributable to the leather. “We’ve had a lot of battles with our leather suppliers over this,” Ms. Blaisdell says. Timberland officials, she says, “just follow the guidelines.”
Timberland officials concede shortcomings with their method. By using an average energy-consumption number for all pairs of shoes, the calculations fail to recognize that some shoes require more electricity to assemble in the factory than do others. And Timberland’s calculations omit the carbon impact of the leather and other materials that fall to the cutting-room floor. “No question, it’s crude in some ways,” Mr. Girard says. “But it’s a step more information than our designers were making a decision on before.”Article from http://www.Earthlab.com M. Germaine Parra
Realtor, Feng Shui Consultant
Licensed in DC, MD and VA
Long and Foster Realtors
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