If readers of this column two weeks ago found the results of the 2001 "Environmental Doomsday Clock" questionnaire depressing, that's not surprising. For the seventh year in a row, respondents worldwide have set the clock at "extremely concerned."

Adding pessimism (realism?) to fear, 68 percent of those who responded to the "clock" survey (conducted by the Asahi Glass Foundation) also predicted that, in 30 years, the state of our environment would be worse. Many cited global warming as a primary concern.

Then, last week, The Japan Times (Oct. 3) reported a recent Cabinet Office poll that found 82 percent of Japanese people were concerned about the environment. Still, there was a glimmer of hope: 80 percent also said they were "willing to change their lifestyles to curb global warming."

So, in the spirit of proactive, upbeat journalism, this column will briefly point an accusing finger at one guilty party, then offer some suggestions for reducing carbon dioxide emissions.

According to the World Resources Institute, a U.S.-based environmental think tank, the United States is the world's top emitter of carbon dioxide. Between 1900 and 1999, the institute reports, the United States spewed out more carbon from fossil fuels than any other nation: 30 percent of the global total. China contributed 7 percent and India 2 percent.

Ten years from now, the WRI says, the U.S. will still be generating the most carbon emissions, despite increasing emissions from developing countries. The combined emissions from India and China will still be only four-fifths those of the United States.

A WRI report issued in June says that a per-capita analysis reveals the same pattern. "In 1999, U.S. emissions averaged about 5.6 tons of carbon per person. This is about 20 times the amount of carbon emission per person in India and more than 10 times that of the average Chinese."

"To get the ball rolling," says Nancy Kete, director of WRI's Climate, Energy and Pollution Program, "climate protection requires the leadership of a few countries that bear historical responsibility for the problem and that have considerable capability to act -- that means first and foremost, the United States."

So here's my ball: some tips on how to reduce carbon dioxide emission in daily life. Clip it, stick it to your fridge, and send copies to all your friends, particularly Americans.

These suggestions are adapted from a list found on the Web site of Environmental Defense, a nonprofit Washington, D.C.-based environmental advocacy group. Keep in mind, the list was written for Americans, who wash more clothes and drive more cars than anyone else on the planet.

Helpful hints for saving our planet Earth:

* Do not use hot water to wash clothes. If you wash two loads a week, without hot water, you can reduce carbon dioxide emissions by up to 227 kg a year.

* Turn down your water-heater thermostat; 48 C is hot enough. The emission reduction (for each 4 C adjustment) is 227 kg a year.

* Lower your thermostat in winter, raise it in summer. For each 1 C adjustment, you can reduce emissions by about 225 kg a year.

* Clean or replace air-conditioner filters as recommended. A clean filter can cut energy use by 5 percent.

* Use energy-efficient florescent bulbs. Replacing one bulb in frequent use cuts carbon dioxide emissions by about 225 kg a year.

* Wrap your water heater in insulation (if the heater is more than 5 years old and has no internal insulation). This can cut emissions by up to 450 kg a year.

* Install a low-flow shower head to use less hot water. This will cut emissions by up to 135 kg a year.

* Seal the gaps around doors and windows to plug air leaks, and reduce emissions by up to 450 kg a year.

* Walk, bike, carpool or use mass transit. Every liter of gasoline you save reduces emissions by 2.6 kg a year.

* If you buy a new car, choose one that gets better mileage. If your new car gets 4 km per liter more than your old one, you reduce emissions by about 1,135 kg per year.

* Insulate your walls and ceilings. Save about 25 percent of home heating bills and reduce emissions by up to 900 kg per year.

* Plant trees next to your home, and paint your home a light color if you live in a warm climate, or a dark color in a cold climate. This can reduce carbon dioxide emissions by up to 2,270 kg a year.

* When you replace home appliances, buy the most energy-efficient models. Replacing an old fridge with an efficient one can reduce emissions by as much as 1,360 kg per year.

* Finally, don't forget to set your clocks back to "concerned, but actively optimistic."