What’s low-tech, sustainable and possibly the most effective thing that we can do to fight global warming and climate change? Planting trees and saving forests.
Tom Crowther is a climate change ecologist at Swiss university ETH Zurich. Four years ago he found there are about 3 trillion trees already on earth — much higher than NASA’s previous estimate of 400 billion. Now, his team of researchers has calculated there is enough room on the planet for an additional 1.2 trillion trees. Planting them would help absorb atmospheric carbon dioxide, the main driver of global warming.
According to one analysis by The Nature Conservancy, reforestation is the single largest “pathway” to increase carbon capture in U.S. lands, with the potential to ramp up to more than 300 million tons of carbon dioxide capture per year by 2025. That powerful potential is why the U.S. Mid-Century Strategy for Deep Decarbonization, compiled in the final year of the Obama administration, called for 40–50 million acres of new reforestation by 2050 to achieve America’s long-term climate goals.
Because his research is currently under review for publication in the journal Science, he says he can’t share exact figures of how much extra CO2 could be stored by those trees. But he points to numbers from Project Drawdown — a non-profit that ranks climate solutions by the amount of CO2 they could remove from the atmosphere. Its number one ranked solution — managing the release of HFC greenhouse gases from fridges and air conditioners — could reduce atmospheric CO2 by 90 billion tons. Crowther says planting 1.2 trillion trees would give a reduction “way above” that figure. To put that in context, global CO2 emissions are around 37 billion tons per year.
But while there may be space for a trillion new trees, is it actually practical to plant that number? One organization that thinks so is youth-led Plant for the Planet (PFTP), which is running the “Trillion Tree” campaign to do just that. Set up as the Billion Tree campaign by the UN in 2006, it was later handed over to PFTP, which has upped its planting ambitions in response to Crowther’s work.
Felix Finkbeiner founded Plant for the Planet in 2007, when he was just nine years old. He is now a PhD student at Tom Crowther’s lab at ETH Zurich. He’s pictured at an award ceremony in 2015.
It has already planted nearly 15 billion trees, with the help of various governments, including India’s, which has planted more than 2 billion trees as part of the initiative.
“I think a trillion trees is achievable,” says PFTP chairman Sagar Aryal. “It’s not that we don’t have enough money in the world — maybe governments alone can’t do enough but if we work together with the private sector we can do it.”
Crowther is a scientific adviser to Plant for the Planet, providing them with information on the best places to restore trees. He says all the locations identified by his team are on degraded land, rather than agricultural or urban areas.
“These are places where farms have been abandoned, or where there’s been deforestation and it’s been left,” he explains.
To successfully fight climate change, it’s vital that the right land is restored. For example, in parts of northern Europe, planting more trees could reduce the heat and light reflected from snowy ground, and actually increase global warming.
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