By Kate McNeil

Comprehending the carbon footprint of the entire human race is a bit like grasping how far away the sun really is. In fact, the number (in pounds of greenhouse gases emitted) has so many zeros, it might span the length of this column.

So what?

The doomsday talk of climate change is enough to make a person feel helpless, but the Riverdale Nature Preservancy is on a mission to help Riverdalians take a bite out of greenhouse gases. The group held its annual meeting on Nov. 1 at Riverdale Neighborhood House and invited environmental experts to discuss how to "live green" in Riverdale.

"Doing the best thing for the environment is seldom easy, seldom cheap and never clear," said Larsen Plano, a green building advocate who arrived late - by train - to reduce his carbon footprint.

While greenhouse gases are not inherently evil, ("Without them we'd be popsicles," Mr. Plano explained) it's the human-induced ones that are eating away at ozone. Since industrialization, Mr. Plano said, we've managed to increase carbon in the atmosphere by 31 percent and methane by 140 percent, all while deforesting the earth.

Whether by flying cross-country, using a leaf blower or not recycling this newspaper, every human contributes to climate change. The good news is there are simple ways to reduce one's "carbon footprint."

You can start by turning off your appliances when not in use. This "phantom power" accounts for 75 percent of your home energy use, Mr. Plano said. Invest in a governmentbacked Energy Star rated refrigerator, the biggest energy user in your home.

Mr. Plano also suggested being smarter about your transportation choices.

"Don't buy the SUV to tow your boat once or twice a year," he said. "Buy the Accord and with the money saved, rent a truck to tow your boat or take a cruise."

"The equation has changed," said Richard Cherry, president of the Community Environment Center, a non-profit energyconservation contractor. "If we're trying to save something it's not just money, it's the earth."