Myth: Plant more trees in the city because they absorb carbon.
Reality: The maintenance of urban trees makes it unlikely they are net storers of carbon.
New York City Mayor Michael Bloomberg is planting a million trees. That offers lots of benefits. But urban trees often require pruning by chainsaw-wielding utility workers in trucks to clear buildings and other obstacles.
"Fossil-fuel emissions from servicing add up," says Jeff Fiedler with the Nature Conservancy, meaning that over time tree care is likely to offset the gains in CO2 stored.
Don't despair. It turns out that trees can boost energy savings. For instance, shading an air conditioner can boost its efficiency by as much as 10%, according to the Energy Department. -- E.F.
NEXT: Energy: Global warming