Does Tree Planting Count?

Planting trees deliberately would seem to be an example of taking action in the face of climate change, right?

For at least 30 years I've accepted the premise that planting trees was good for the environment in general, and helpful at stemming global warming in particular. Not only do trees anchor the soil and hold moisture there, they provide homes and "services" to other critters, shade for cooling the earth and overheated picnickers, and - most relevant to global warming - they absorb CO2 while producing oxygen.

Lately, though, this accepted advantage of carbon sequestration by trees has come under attack from scientists who see a dark side to trees - at least in temperate and subarctic latitudes.

The U.S. Forest Service has begun a program where citizens can contribute 6 dollars to offset one ton of carbon dioxide through treeplanting programs in various U.S. locations. The program and its basic assumptions are under attack by some climatologists.

Not every scientist agrees that planting more trees in the United States will cut greenhouse emissions. Ken Caldeira, a climate expert at the Carnegie Institution at Stanford University, says restoring forests outside the tropics will do little or nothing to stop climate change.

Trees absorb more sunlight than the ground so they can add to warming, according to Caldeira. The effect rises when the ground is covered in snow, which reflects the sun's heat back into the atmosphere.

One thing we don't want is for people to be sold on taking actions that do little to change the trend toward climate change while offering them a feeling of complacency that, "Now I've done something to help. I can relax now."