Reduce your carbon footprint, just $940

Cruising through Twitter, I stumbled on a tweet from Mark Grossi, a former coworker at the Fresno Bee who has the environmental beat.

Grossi's tweet asked, "How big is your carbon footprint?" Intrigued, I clicked on the site. Nature Conservancy.

So far, so good. I took the bait, entered the information for a four-person household, three-bedroom home in California. The brief survey asked questions about heat and home efficiency, lighting, use of Energy Star appliances and measures taken to reduce hot water use.

Not the most illuminating. But, I guess, not bad.

The survey also asked for a list of our cars, how fuel efficient they were and how many miles driven in a year. Other questions included how often an air filter on the furnace/AC was replaced and how often tire pressure is monitored.

The final question boosted my family's footprint. We took the equivalent of six short flights in the past year. Peg and I went to Vegas, she and I to Bellingham, Wash. to visit our latest grandchild and she and Calvin, our oldest son, went to check out two colleges in Seattle.

And I plan to fly back after dumping him off at Seattle University this fall.

In total, and perhaps a little short, our footprint amounted to 47 tons of carbon dioxide a year. Not bad when compared with the U.S. average of 110 tons, but it's more than twice the world average of 22 tons for a family of four.

And we do pretty decently. I insulated my floor last winter. I've installed double-pane windows with coatings to reduce the sun's rays during hot summer days. I have all Energy Star appliances, and I just cleaned the dust from the fridge's cooling coils. They get nasty by the way.

My electric bill was $200 in June. Not great but I know people who would kill for one so low in our super-heated San Joaquin Valley.

And I'm always on the lookout for more things I can do. This encouraged me to click on the "Offset your carbon footprint" link.

I expected tips on insulating, driving less, riding bikes, maybe purchasing pieces of the Rain Forest.

What you get is a pitch: "Offset your footprint with The Nature Conservancy, you'll help protect land, plant trees and sequester carbon over the next 70 years. Your tax-deductible gift will make a difference for our lives, our environment and future generations."

Cost: $940.

Not that there's anything wrong with that. The Nature Conservancy is a worthy organization, deserving of donations.

But I envisioned a more mathematically precise calculation. I'll have to keep working on that.