Why is it Important to Reforest the Tropics?
In October 2019, the International Panel on Climate Change released a Special Report held by the world's top scientists. It was long-awaited by the signatory parties of the Paris Climate Agreement in 2015 to limit the temperature to below 2 degrees Celsius increase.
The scenario-based study revealed that keeping the Earth's temperature below a 1.5 degrees Celsius increase will make a huge difference, especially in decreasing extreme heat. But this will require fast and drastic cuts in greenhouse gas emissions, thus changing all aspects of our modern societies. It also emphasises the relevance of reforestation to neutralise emissions.
Reflecting on this, TreeSisters has embarked on a path that channels profound personal transformation into the healing of life on Earth. One of the actions we have chosen to move toward becoming a restorer species is to reforest the tropics.
Best natural carbon capture solution
Reforestation is considered the best natural carbon capture solution to mitigate some carbon emissions. It is a complex solution to implement large scale. Still, it is certainly less controversial than, for example, carbon capture storage technologies, which could grant governments and industry the right to continue emitting Greenhouse Gases and possibly deforestation, with business as usual.
Of all the Earth's forests, tropical forests have the highest potential to draw down carbon from the atmosphere. The largest vegetation and soil carbon pools (reservoirs of carbon that can both take in and release carbon) are in tropical forests (60 and 45% of the total, respectively) (1) - because of their large extent and high carbon density. (2)
And the highest carbon density is present in tropical wetlands, such as mangrove forests and peat swamps forests. (3) Of all terrestrial biomes on Earth, tropical forests are the most productive - varying with humidity and forest age. Tropical forests are 2-3 times more productive than terrestrial biome. This is caused by the combination of high average precipitation and temperature- for amazing productivity of new plant materials.
Pivotal for biodiversity conservation
Any tropical forests usually hold more species than any other terrestrial biome. Two-thirds of flowering plant species grow in the tropics. (4) A square kilometre of tropical forest may be home to more than 1,000 tree species (7). They also harbour many rare and specialized plant and animal species.
But tropical forests are shrinking fast. Of all forest biomes, tropical forests exhibit the most significant forest losses. And in the tropics, forest losses easily outstrip forest gains (forest natural regrowth and reforestation by mostly plantation forests) - turning tropical forests into net carbon emitters and reducing the coverage of tropical natural forests.
According to the World Resources Institute, today, the Earth's forest area is 70% of what it used to be before human presence. Of that, only 15% remains intact - and only 20% within tropical forests. (6) If we don't replant what's cut down, we will keep encroaching on and losing them.
Sadly, local population decline and species extinction are most extreme in the tropics (7), due to the loss of vibrant tracks of ecosystems which are home to half of the Earth's species. The fragmentation of tropical forests is responsible for the average extinction of 100-200 species a day. (8)
Climate Role of Trees in the Tropics
The relationship between trees, water, and climate is prime in the tropics. Indeed, forests, particularly rainforests, regulate local and regional weather through their capacity to absorb and retain water and the creation of rainfall. Cutting down tropical forests directly reduces rainfalls. Some of Mount Kenya's perennial streams have stopped flowing in Kenya, a highly deforested country.
For the Amazon water basin, which already suffers from modified rainfall patterns that affect the forming vegetation patterns, (9) it would result in the decline of the Amazon mean river flow by up to 25% (according to the IPCC Special Report).
So how does it work? Trees harvest water from rainfall, pump water from the soil, and release it into the atmosphere through evapotranspiration. When the air is saturated with water, it falls into precipitations which feed rivers and refill groundwater. Trees can also release volatile compounds to trigger rain.
Trees are especially crucial under tropical temperatures. The IPCC's Special Report projected (with medium confidence) that 2 degrees Celsius more would increase the number of highly unusual hot days in the tropics. Trees cool down the local temperature. Cutting down tropical trees increases the local surface temperature by 3 degrees Celsius.
This is possible because forests are like "parasols": they reflect the solar energy to the atmosphere. Trees are incredible air-conditioning systems. The clouds resulting from evapotranspiration screen off sunlight back into the atmosphere, cooling off the air locally. And the process of trees' evapotranspiration also pumps energy out from their surroundings.
We'll be exploring two core approaches to our restoration approach in the coming months. I'll also be shining a light on what your generous donations support.
1. IPCC, 2001
2. Although, on a per unit area basis, some coastal temperate forests, called 'Ocean forests' have higher carbon density than tropical forests.
3. Pan, 2011
8. WWF's Global 200 ecoregions
9. Malhi et al. 2008. http://www.yadvindermalhi.org/uploads/1/8/7/6/18767612/malhi-2008-climate_change_deforestation_and_the_fate_of_the_amazon.pdf