seen as a critical step in minimising greenhouse gas emissions. However, comprehensive new data show that this dense growth of trees and underbrush deliver climate benefits well beyond just storing carbon.
The study, conducted by researchers from the US and Colombia, shows that forests play a more complex role in tackling climate change owing to their physical effects on global and local temperatures. It found that overall forests keep the plant cooler by at least half of a degree Celsius when biophysical effects are combined with carbon dioxide, although the band of tropical rainforests spanning Latin America, Central Africa and South-East Asia generate the most benefits. In the tropics, from Brazil and Guatemala to Indonesia, with Chad and Cameroon in between, the cooling effects are more than one degree, the study says. In other words, while forests provide multiple benefits, some of them play a more critical role than the others in tackling the climate crisis.
“Despite the mounting evidence that forests deliver myriad climate benefits, trees are still viewed just as sticks of carbon by many policymakers in the climate change arena,” Louis Verchot from the International Center for Tropical Agriculture (CIAT) and co-author of the study The Unseen Effects of Deforestation: Biophysical Effects on Climate, said. “Forests are key to mitigation, but also adaptation.”
Researchers say that a range of biophysical effects of forests, including the physical aspect of the tree’s leaves, wood and density enable them to cool the planet. They have found that chemicals called biogenic volatile organic compounds (BVOCs) are emitted by forests which create aerosols that have cooling effects by forming clouds and reflect incoming energy. While they also generate ozone and methane, two common greenhouse gases, on balance, the cooling outweighs the warming.
“The biophysical factors don’t cool the planet, but they do change the way we experience heat, and that matters,” said Deborah Lawrence, the lead author of the study from the University of Virginia, said. “The heart of the tropics is at the heart of the planet and these forests are critical for our survival.”
