Geography Reference
In-Depth Information
I may be of a tree or two, but I counted 362 of them on my two acres. Each
of them is busy converting its annual one hundred pounds of carbon dioxide
into a tenth of an inch of wood. And all that photosynthesis adds up. In total,
my trees hold about 570,000 pounds of carbon and annually store an addi-
tional 10,000 pounds. And that's just the aboveground carbon; 20 percent to
30 percent more is stored belowground, in the soil and roots of my forest.
All that carbon storage sounds impressive, but how does it compare to the
carbon my wife and I emit as we power our house, drive our cars, and live
average American lives? I expected our carbon emissions to dwarf our trees'
carbon consumption. But I was wrong! Using an online carbon calculator, I
learned that our lifestyle produces just under thirty thousand pounds of car-
bon dioxide per year—equivalent to seventy-nine hundred pounds of carbon.
Most of this comes from the natural gas we use for heat, though a substantial
part also comes from our use of household electricity, gasoline for our cars,
and airplane travel. The good news is that it is less than the amount of carbon
that our trees annually sequester. Our yard is a carbon sink! In truth, our car-
bon emissions are greater still; our two daughters also travel extensively, but
at least on a local level our trees are doing their part to alleviate our conversion
of fossil fuels to climate-changing pollution.
Now, think about the ef ect that we could collectively have on carbon if
only half of America's turl ands—twenty million acres—could do what my
trees do. Turf consumes carbon just as does any plant, but unlike trees, grass
doesn't put on an annual layer of wood. Its use of carbon dioxide increases the
soil's carbon stores. Estimates from 2003 suggest that an acre of U.S. grass
annually adds about eighteen hundred pounds of carbon to the soil, and it
continues to do so for about thirty years after it is planted. An acre of my trees
did about three times that amount, in aboveground carbon storage, and they
have been doing so for seventy years. Their annual storage capacity will slow
as they age, probably in a century or so, but their overall capacity to buf er our
climate is magnitudes beyond what grass could ever hope to do. Still, if we
