Daily Score Blog

When my wife and I bought our house, the yard was typical for our neighborhood: a mostly barren plain of lawn so sunbaked that you could bounce a tennis ball off it. So being eco-groovy types, we've tried to improve the place: we put in a rain barrel, built a natural drainage system, and added topsoil planting berms. But I'm most proud of the trees we've planted: a pair of akebono cherries in the parking strip and a white-star magnolia in the front yard; and in the backyard, a shore pine, a Chinese dogwood, a couple of vine maples, a Japanese maple, and a limelight cypress.

I recently began wondering how much carbon our new trees are soaking up. Since tree planting is the sine qua non of carbon offset programs, how much of my emissions are offset by my yard? Enough, perhaps, to justify moving from a dense highly walkable neighborhood to a still-urban but less foot-friendly place? (My Walkscore dropped from 92 to 80.)

The answer, I'm afraid, is "no."

I estimate that in an average year my nine trees will soak up right around 100 pounds of carbon-dioxide combined. (Brief methodology note at the end of this post.) That's the emissions equivalent of burning 5 gallons of gasoline -- or actually just 4 gallons, if you consider the "lifecycle" emissions of gas. In other words, my tree planting allows me to burn about one-third of a tank of gas guilt-free each year.

That's certainly better than nothing. But then again, the average American is responsible for about 45,000 pounds of yearly CO-2 emissions from energy use alone. Nine trees like mine offset about 0.2 percent of those emissions -- and much less when non-energy sources are considered.

Even giving myself a big benefit of the doubt -- my electricity is carbon-free hydro and I take other steps to reduce my climate footprint -- it's highly unlikely that my trees are offsetting more than half a percent of my annual emissions. Plus, half of those tree offsets belong to my wife. So that means at the very, very most I'm offsetting about one-quarter of one percent of my own emissions.

I could do more for the climate by simply avoiding a couple of trips in my car.

I know that the home mortgage industry has taken a beating recently. But this actually sems like good news to me.

Lenders are [offering] homebuyers bigger loans or discounts if they are making energy-efficient improvements -- or if their new home meets certain efficiency standards....

[E]nergy-efficient improvements could save a homeowner $50 a month. The $600 extra a year could allow a person to borrow about $10,000 more on a 30-year mortgage.

OK, I suppose that some people will say that this is just a way for mortgage brokers to sucker home buyers into going even deeper in debt. Just buy a better furnace, and you're on your way to a bigger mortgage!

But I think that's too cynical. Energy efficient homes really are cheaper to operate, which gives homebuyers a little extra cash to buy a home that they'd really like to own.

And even though rolling energy efficiency into a mortgage payment may seem like a subtle change, I think it has the potential to be a really big deal, since it helps overcome what may be one of the biggest obstacles to efficiency investments: shortsightedness.