Only tropical rain forests are strongly beneficial in helping slow down global warming, according to researchers from Stanford University and Lawrence Livermore National Laboratory, San Jose Mercury News reports.

While the study suggests it is more important than previously recognized to preserve and restore tropical forests, trees in snowy regions may actually increase local warming, the researchers said.

According to the article, tree planting efforts to increase the forested areas in northern regions may be ineffective.

Tree planting projects to offset carbon emissions have been rejected by many environmentalists.