Tropical forests are often lauded for their ability to sequester and store carbon — and it’s no wonder, given they store about one-quarter of all land-based carbon.
But just as tropical forests are more than tall trees, so too are they far more than powerful carbon sinks.
In fact, tropical forests provide us with a swathe of ecosystem services, including ensuring water quality, cooling global temperatures, helping to prevent pandemics, slowing floods and advancing human healthcare.
Each of these services is life-sustaining and worthy of attention. So let’s take a closer look at each, and marvel a little, shall we?
Filtering our drinking water
When it rains (as it often does in the tropics), extensive root systems anchor soil and prevent erosion, and material on the forest floor absorbs nutrients and sediment, allowing cleaner water to flow into waterways.
When forests are damaged, soil pollutes our waterways, which requires the construction of costly man-made water filtration plants, which are far less economical than nature’s natural filtration system.
An often-cited example of forest superiority comes from New York. The city invested $1.5 billion to protect more than 1 million acres of mostly forested watershed area, avoiding $6-8 billion on the cost of building a water filtration plant, as well as $300 million in annual operating costs, with the added bonus of all the other ecosystem services (see above and below) provided by the forest too.
Keeping the planet cooler
Tropical forests work tirelessly to regulate the planet’s average temperature.
To understand how powerful this cooling power is, one need only look at the warming effect of deforestation. We all know the hottest days of the year are getting even more intense, but did you know deforestation is to blame for a third of this life-threatening trend?
Notably, while two-thirds of a tropical forest’s cooling power comes from sequestering and storing carbon dioxide, the other one-third is the result of a mixed bag of tricks, including humidifying the air, reflecting sunlight back into space, creating clouds and releasing cooling chemicals.
Preventing future pandemics
It’s estimated that 1.7 million currently ‘undiscovered’ viruses exist in mammals and birds, of which up to 827,000 could infect humans. And there is evidence that deforestation drives zoonotic disease outbreaks, by creating pathways for diseases to spill out of forest boundaries into human and livestock populations.
By protecting our forests, we are protecting ourselves from future pandemics too.
Slowing down floods
Without trees, rainwater would run off soil, directly into waterways, and with this rapid rise in water levels, cause uncontainable floods. But tropical forests combat this process at every turn.
The canopy intercepts, disrupts and slows rainfall, allowing some water to evaporate back into the atmosphere before it ever reaches the ground. Deep root systems help water quickly penetrate the soil, where it is stored, and shrubs and deadwood act as a drag on water, slowing its movement and decreasing flooding risk.
It is teamwork at its finest.
Medicine’s biggest inspiration
About 25% of all drugs used in modern medicine are derived from rainforest plants, and researchers believe that about 70% of rainforest plants have anti-cancer properties.
But while it is tropical forests that grow these plants, we must thank the world’s Indigenous Peoples for uncovering their life-saving properties. Quinine is isolated from the bark of the cinchona tree, found in tropical rainforests in the Andes, and was used as traditional medicine by the Quechua Indians. Today, it is used to treat malaria. Cortisone comes from wild yams found in tropical rainforests in South America, where it was used by Native Americans as traditional medicine. Today, it is an active ingredient in birth control pills. And vincristine and vinblastine are derived from the rosy periwinkle, a plant used by the traditional healers and found in the rainforests of Madagascar. Today, they are used to treat pediatric leukaemia and Hogkin’s disease.
A home for biodiversity
While it isn’t an ecosystem service in and of itself, high biodiversity maintains these services, and keeps them resilient to external pressures. This is because every species plays a unique and often irreplaceable role in the creation of ecosystem services: from the pollinators and the scavengers to the foragers and the secreters.
And when it comes to biodiversity, tropical forests take home the trophy.
Even though tropical forests cover about 6% of the Earth’s surface, they host more than 80% of the world's documented species.
In fact, one tree in the Peruvian Amazon can house more ant species than the entire British Isles, which have a total area of 315,159 km². In another mind-blowing example, there are more tree species in 1km² of tropical Malaysian rainforest than in all of the United States and Canada combined.
So next time you have a sip of water, visit the pharmacy, marvel at the world’s weird and wonderful animals, or enjoy a predictable day of weather, spare a thought for the tropical forests doing the hard work. And next time someone calls them a ‘powerful carbon sink’ and ends it at that, tell them what they are missing.
