As they grow, the big trees of the world’s tropical forests store carbon from the atmosphere in their leaves, bark, roots and the organic material contained in the soils beneath them. It is this role that makes big trees critical in the regulation of the Earth’s climate, and in the mitigation of climate change. Collectively, it is estimated that the trees of which the tropical belt that rings the Earth is formed, in forests that are home to 96% of the world’s tree species, store 25% of all the planet’s carbon.
Scientists from the International Panel on Climate Change have identified tropical trees as essential to solving many of the environmental and social challenges posed by climate change. Forests located anywhere on the planet contribute to carbon sequestration, but it is equatorial forests which contribute most to “cooling” the Earth. Across the world, tropical trees are responsible for more than 95% of all the carbon sequestered by all trees species on the planet.
Scientists have calculated that, on average, in tropical rainforests like those of Tambopata National Reserve, tree leaves store some 5 tons of carbon per hectare, branches 75 tons of carbon per hectare, tree trunks 120 tons, roots, 30 tons per hectare, dry wood and dead leaves 10 tons per hectare, and soils 100 tons per hectare, with small vegetation (undergrowth) accounting for an additional 10 tons per hectare. This means that tropical forests can store up to 350 tons of carbon in every hectare of primary growth.
Because they grow so much faster than their counterparts in the forests of the north, tropical tree species have a much denser biomass. In fact, over 50% of the woody biomass of a tropical tree is composed of sequestered carbon. While the big trees of northern forests might take anything from eighty to one hundred and twenty years to reach maturity, across the world most tropical hardwoods mature in around twenty years.
In addition to mitigating global warming through carbon storage, tropical forests work to cool the Earth by producing clouds. Tropical forests are constantly converting the solar energy they require into water vapor, increasing the reflectivity of cloud formations and producing a cooling effect. Anyone who has spent any time at all in tropical forests can attest to the cool temperatures experienced on cloudy or mist-shrouded days.
Because the trees of pristine forests store carbon in their wood, leaves, branches and the soils they are rooted in, when forests are cleared carbon is released into the atmosphere. Deforestation currently accounts for 20% of the world’s total carbon emissions, which is why the United Nations has focused efforts on convincing tropic nations of the need to find ways to reduce deforestation.