How Many Trees Can We Plant?

In casual conversations with CARE Members, supporters and energy consumers we find a universal confusion about carbon offsets and carbon credits. We previously featured a great piece on carbon credits. (If you have not read it, please check it out.) Today, this posting came in from one of our energy counsel members: Dennis Avery. If you have ever wondered how many trees you can plant, you find this article fascinating. It answers a lot of questions you may have. Read on and tell us what you think!

Planting Trees To Keep The Lights On
It’s the Christmas season, the UN’s Bali conference has just ended, and we should all have trees in our thoughts. The most popular way for people concerned about global warming to offset their “carbon footprints” is to buy carbon credits earned by planting trees. The additional trees absorb additional CO2 in their leaves, boles, and roots, and keep it from aggravating global warming in the sky. Unfortunately, the realities of tree-growing don’t give much confidence that U.S. forestry will much ease the global warming problem.

In the first place, existing forests don’t count as carbon offsets, because they’re already storing their normal ratios of carbon. The Kyoto treaty counts only trees planted after 1990 for carbon offset—and only on lands that have been treeless for at least 50 years.

America’s western forests are near their natural limits, and our eastern forests are limited by the large amount of farmland needed to grow food—and biofuels. Farmland is scarce. Forest land is scarce too, when you need hundreds of millions of hectares to make a climate impact.

Some optimists have concluded that large-scale forestry projects in the U.S. could offset about one-third of America’s annual CO2 emissions—about 500 million metric tons of carbon per year. However, a more cautious examination of tree growth rates indicates that the United States doesn’t have much additional land available for new forests.

Brandon Scarborough, writing for the Mountain States think-tank PERC, says carbon accumulates in existing forests at up to 0.36 metric tons of carbon per acre per year in the central Rockies and the Southwest, and at 0.64 to 0.91 metric tons per acre in the Pacific Northwest and the Southeast—with lots of regional variation. Plantation forests in the Southeast and the Pacific Northwest sequester the most carbon, but they’re already planted, and already managed for high yields on 40-year rotations.

Scarborough says no more than 25 million acres of currently un-forested U.S. land are able and likely to grow trees in the future, even with the promise of carbon credit payoffs. That’s about one-fourth of Maine’s land area. If those new forests sequester an optomistic one ton of carbon per acre per year, that would offset only about 2 percent of America’s annual CO2 emissions.

That’s assuming no forest fires, of course—which would quickly put most of a forest’s carbon back into the atmosphere.

Corn ethanol produces a net gain of only 50 gallons worth of gasoline per acre per year, against a demand of more than 134 billion gallons annually. That’s essentially no help at all. Hybrid cars are popular, and the Prius gets more than 40 mpg—compared with about 26 for the average car and maybe 18 mpg for the average SUV. But the Kyoto strategy will demand that Americans give up at least 80 percent of their current energy supplies. An 80 percent energy reduction doesn’t say “Prius,” it says “bicycle.”

Solar panels are expensive, and in much of the country there isn’t that much sunshine. Ditto for windmills, unless you live on San Francisco Bay or in North Dakota.

No wonder the world is re-examining nuclear power plants. France gets 80 percent of its electricity from reactors. Finland is building a new nuclear plant, and Eastern Europe is planning dozens. Germany’s prime minister says she will stop her country’s planned nuclear phase-out. China and India are each aiming for 30 nuclear plants in the next 15 years.

If that’s the only way to keep the lights on and the computers running. . . .


DENNIS T. AVERY was a senior policy analyst for the U.S. State Department, where he won the National Intelligence Medal of Achievement. He is the co-author, with atmospheric physicist Fred Singer, of the book, Unstoppable Global Warming—Every 1500 Years, available from Rowman & Littlefield. Readers may write him at the Center for Global Food Issues (http://www.cgfi.org/) Post Office Box 202, Churchville, VA 24421.