NEW HAVEN — AS international leaders gather in New York next week for a United Nations climate summit, they will be preoccupied with how to tackle the rising rate of carbon emissions. To mitigate the crisis, one measure they are likely to promote is reducing deforestation and planting trees.

A landmark deal to support sustainable forestry was a heralded success story of the last international climate talks, in Warsaw last year. Western nations, including the United States, Britain and Norway, handed over millions of dollars to developing countries to kick-start programs to reduce tropical deforestation. More funds are promised.

Deforestation accounts for about 20 percent of global emissions of carbon dioxide. The assumption is that planting trees and avoiding further deforestation provides a convenient carbon capture and storage facility on the land.

That is the conventional wisdom. But the conventional wisdom is wrong.

In reality, the cycling of carbon, energy and water between the land and the atmosphere is much more complex. Considering all the interactions, large-scale increases in forest cover can actually make global warming worse.