PARIS - If you want to fight climate change, plant a tree. Or stop one being chopped down, particularly in tropical rainforests.
With carbon dioxide (CO2) emissions from burning fossil fuels, bushfires and deforestation accumulating in the atmosphere, tropical forests are a good way to soak the stuff out of the air. But we keep chopping them down, millions of hectares every year.
In a study published in the journal Nature Climate Change on Monday (Dec 7), scientists have estimated that reducing tropical deforestation, expanding the tropical forest area and restoring degraded tropical forests could cut net carbon emissions by more than 18 billion tonnes of CO2 per year, the equivalent of nearly half of current annual global CO2 emissions.
That's a big number and underscores the key role forests can play in curbing the pace at which the planet is warming. Forests have been a focus at UN-led climate talks in Paris, which aim to seal a global deal to fight climate change by the end of this week.
Tropical forests, such as those in the Amazon, South-east Asia and central Africa, help regulate the climate by taking up large amounts of CO2 and storing it away. These forests lock away hundreds of billions of tonnes of carbon in the trees and in the soil. But clearing them releases CO2 back into the air and limits their ability to act like a giant carbon sponge.
The goal of the Paris climate agreement is to ultimately limit average global warming to 2 deg C to try to avoid catastrophic impacts of more extreme weather and rising sea levels. One way to limit warming is to slam the brakes on fossil fuel emissions.
The study led by Dr Richard Houghton, a senior researcher at the Woods Hole Research Center (WHRC) in the United States, found that relying on cutting fossil fuel emissions to achieve a 75-per-cent likelihood of avoiding warming in excess of 2 deg C meant these emissions would have to be eliminated over the next 20 years or less. That seems unlikely.
The same could be achieved if, first, tropical forest management removed 18.35 billion tonnes of CO2 from the atmosphere, phased in linearly over the next 10 years.
And second, if fossil fuel emissions were held constant for the next 10 years and then reduced linearly to a level equal to 20 per cent of 2014 emissions by 2050 before further linear reduction to zero by 2100, WHRC said in a statement accompanying the study.
Dr Houghton and his colleagues estimated that nearly four billion tonnes of annual carbon emissions could be eliminated by stopping tropical deforestation and a further 3.7 billion tonnes could be removed from the atmosphere each year by expanding the tropical forest estate over several hundred million hectares.
So there is hope we can stop the world overheating. And nature has already provided us with the right tool - trees. We just need to better appreciate the true value of rainforests.
