Why forests are key to the climate - and not just to absorb carbon
The Alaska Highway is surrounded by boreal forest running north towards Whitehorse, Yukon in this file photo taken June 21, 2007. REUTERS/Andy Clark
What’s the context?
From reducing temperatures to stopping disease, forests play a bigger role than just cutting emissions to combat climate change
- Forests are world's biggest land-based carbon absorbers
- Rainfall stabilisation, cooling among other benefits
- Deforestation threatens global food and water security
LONDON - From the Amazon rainforest to the boreal forests of the northern hemisphere, forests play a crucial role in absorbing planet-warming carbon dioxide (CO2) as the world faces a race against time to avert the worst impacts of climate change.
Forests are the largest carbon sinks on land, removing approximately 7.6 billion metric tonnes of CO2 each year from the atmosphere, which is around one-and-a-half times the average annual emissions of the United States.
Governments are taking action to protect these natural stores of CO2, with more than 140 countries pledging at last year's U.N. COP26 talks to halt and reverse forest loss by 2030, although a recent analysis found they are not on track.
The Forest Declaration Assessment found that deforestation worldwide slowed by 6.3% in 2021 compared to the 10% annual reduction needed.
But protecting forests doesn't just protect their crucial carbon-absorbing abilities.
Forests also are vital for the climate and nature in myriad other ways, providing benefits that scientists are increasingly able to quantify.
So what else can forests do for the planet and its people?
Help to cool down the globe
The cooling impact of forests goes beyond their ability to absorb planet-heating CO2 emissions.
Keeping tropical forests standing provides a 50% greater impact on lowering global temperatures then can be accounted for simply through their carbon-absorbing abilities, according to a new report by the World Resources Institute (WRI), a think tank.
"Forests are even more important than we thought for stabilising the climate," said Frances Seymour, a WRI senior fellow who co-authored the report.
Stands of trees, for instance, provide "evapotranspiration" - the process by which water is released from the soil into the atmosphere to fall as rain.
Such additional cooling impacts must be integrated into governments' climate policies to fully reflect what forests do for the planet, the report said.
Support food and water security
Forests help to maintain stable rainfall patterns and local temperatures, which are vital for food and water security, according to the WRI report.
Michael Wolosin, a report co-author from the non-profit Conservation International, said the disruption to the world's food system caused by Russia's invasion of Ukraine underlines the need to protect global forests.
Deforestation risks disrupting rainfall patterns that support agriculture, a threat that "is very real, and is something that we need to address through global negotiations," he said.
The Brazilian Amazon, for example, the report said, helps to maintain vital rainfall in several other countries, affecting agricultural production as far as Argentina.
As deforestation turns parts of the world's largest tropical rainforest into dry savannah, scientists are concerned that the Amazon is edging towards a tipping point beyond which it might never recover.
Protect people against natural disasters
Another benefit that forests provide is their ability to act as a buffer against natural disasters, which have become increasingly common due to climate change.
Tree canopies can intercept rainfall and slow it down in a storm, allowing up to 30% of the water to evaporate into the atmosphere without reaching the ground, according to Britain's Woodland Trust charity.
Some cities are using urban forests to become more resilient to flooding, as trees provide more permeable land to absorb rainwater.
In Sierra Leone's capital of Freetown, for example, after devastating landslides in 2017, the mayor's recovery plan included training residents to plant 21,000 native trees.
Across the world's equatorial regions, mangrove forests not only store significant carbon but provide a defence against coastal erosion and storm surges.
Defend global biodiversity
Another vital contribution of forests is their impact on biodiversity, with such ecosystems home to more than half of the world's land-based animal and plant species.
As well as protecting nature, forests can provide a range of benefits to people, from forest foods to medicines.
Especially in tropical regions, deforestation has been linked to increased outbreaks of infectious diseases, in particularly as animals come into closer contact with people.
According to a recent analysis by the World Wildife Fund (WWF), the world's wildflife populations have declined by more than two-thirds since 1970, with deforestation a major driver.
In the Amazon, more than 10,000 species are at risk of extinction due to the clearing of rainforest for uses such as cattle ranching and soy farming.
Provide sustainable living for communities
Deforestation leads directly to increases in local temperatures, exposing people and crops to heat stress, WRI said.
These local temperature extremes are a particular threat in the tropics for small-scale farmers, agricultural workers, indigenous people and other local communities, said Seymour of WRI.
Indigenous communities in particular rely on forests for their way of life. Research shows that they are also the best people to conserve these areas, leading to calls to put more resources in the hands of frontline communities.
In the Amazon basin, a 2021 report by the U.N.'s Food and Agriculture Organization (FAO) showed that deforestation rates are up to 50% lower in indigenous peoples' forest lands than in other areas.
As world leaders look to tackle a growing climate, nature and biodiversity crisis, they should take the multiple roles of forests more seriously, the WRI report authors said.
"Forests really are part of the broader picture to keep communities healthy and safe in a changing climate," Wolosin said.
(Reporting by Jack Graham; Editing by Kieran Guilbert)
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