It's time for another Slate Green Challenge

The United Nations says that the average American is responsible for about 22 tons of carbon-dioxide emissions every year, compared with an average of six tons per person throughout the rest of the world. Scientists are sure those emissions matter: Even a small rise in global temperature could significantly change the climate, potentially resulting in major storms and droughts, disruption of the food supply, and the spread of disease.

When we ran the Green Challenge last fall, some readers noted that individual carbon diets can go only so far in addressing climate change and that it's even more important to change the menu of options that individuals—and businesses—have when they're making choices about energy use. Along those lines, here are three ideas from the nonprofit Environmental Leadership Program.

Create a market:  A tax on carbon, or a cap-and-trade proposal like the ones before Congress, would lead to price-setting for carbon dioxide emissions. That would cause a ripple effect throughout the economy, giving us an incentive to factor in CO2 emissions and energy efficiency as we make choices.

Raise standards:  Replacing incandescent light bulbs with compact fluorescents in one's own house is great, but what about retiring all the incandescent bulbs in the country? Australia recently set a phaseout date of 2010, and the European Union appears ready to follow suit. Similar proposals have been introduced in several states, including California. There is precedent for this kind of eco-mandate: When California set efficiency standards for refrigerators, gas furnaces, and other appliances in 1977, the state reduced the growth of electricity demand for the next generation. Fuel-economy standards and emissions limits for cars and trucks are more critical versions of policies that force technology changes.

Cut commutes:  Transportation is a major source of emissions. What if we cut the travel out of work? Senators Ted Stevens, R-Alaska, and Mary Landrieu, D-La., recently introduced a bill to make nearly all federal employees eligible to telecommute. Alternatively, could we bring jobs and people closer to each other? "Smart growth" policies spur mixed-use development around transit hubs and revitalize urban centers.

Week 1:  Transportation

Transportation is one of the biggest culprits in human production of carbon dioxide—the source of about one-fifth of global-warming emissions worldwide. In the United States, two-thirds of the oil consumed goes toward powering vehicles, according to the U.S. Department of Energy. Passenger cars alone are responsible for 25 percent of the greenhouse gases we produce.

Some suggestions for reducing the miles you log in the car and on the plane:

• Keep your tires properly inflated by checking them regularly when you fill up at the gas station. Environmental Defense notes that 32 million U.S. vehicles ride on at least two under-inflated tires, wasting 500 million gallons of gas each year.

• Drive 65 miles per hour instead of 75. This increases fuel efficiency by 15 percent, thereby reducing emissions. And speeding tickets.

• It seems almost too obvious to point out, but idling cars get zero miles per gallon. According to the Department of Energy, no more than 30 seconds of idling is needed to warm up a car, even on cold winter days.

• OK, so it's a long way and you have to fly. Consider buying carbon offset credits from a company such as TerraPass or Native Energy. You calculate your annual carbon emissions for flying and then buy a credit to help offset the pollution. The money funds renewable energy projects like wind farms. (Read this Slate piece for more details and analysis.) You can buy offsets for your car's emissions, too. Though some critics contend that you can't buy your way green, we say buying carbon offsets is better than doing nothing.



I took the Transportation quiz, and here's what it said:

Your baseline score is 10,549.

The average American score is probably about 20,000 pounds of CO2.


Hooray! I agreed to attempt to check my tires regularly, since driving on underinflated tires wastes up to 500 million gallons of gas annually, nationwide. That would save me 250 points, or 2%.

Since I'll be flying to San Franciso in a few weeks, I decided to check out the TerraPass program, just to see what it was like. I figured it would be vastly out of my budget, but it turns out I can balance the 1,473 lbs of carbon dioxide that my share of the flight will generate by purchasing a $10 TerraPass package. Huh. I think I'm going to go for it.

Your emissions report

Personal emissions:  1,473 lbs CO2
Miles flown:  3,778 miles
Personal fuel use:  75 gallons
3,778 miles:  1,473 lbs CO2

How does a Flight TerraPass work?

Your purchase of a Flight TerraPass results in reductions in carbon dioxide emissions elsewhere, by funding industrial efficiency and renewable energy projects such as wind farms.

Renewable energy from wind reduces carbon dioxide emissions by displacing power generated from fossil fuels. And industrial efficiency projects reduce carbon dioxide emissions through conservation.

In this way, your Flight TerraPass results in a guaranteed reduction in carbon dioxide emissions, balancing out the global warming impact of your flying.


Cool. The challenge is already in its fourth week, so I'll be playing catch-up for a little while. Are you up for the challenge?