A Swiss research team reaches these remarkable conclusions after analyzing tens of thousands of satellite images of the earth’s surface. There are currently around 5.5 billion hectares of forest on Earth, an area twice the size of Europe. But in addition, about 1.7 to 1.8 billion hectares are ’empty’: an area roughly the size of the US that is not used for agriculture or cities, where there is hardly any human activity, and where forests could grow well.
You could grow a total of 0.9 billion hectares of green treetops, the research team led by Swiss ecologist Tom Crowther estimates in the prestigious science magazine Science. And that’s not all: in cities and in the countryside there is room for a good 0.7 billion hectares of tree tops, according to the Swiss: an area slightly smaller than India.
All in all, such a tree offensive is enough to store as much as 205 billion tons of carbon, according to the calculations – after all, trees convert CO2 into matter and oxygen. That is two-thirds of the approximately 300 billion tons of CO2 that humans have emitted since the industrial revolution. “It takes tens of years for forests to mature,” says Crowther in an explanation. “But if we take action now, it can reduce CO2 in the atmosphere by a quarter, to a level that we haven’t had for nearly a century.”
Last fall, the UN climate panel already calculated to the IPCC that, in addition to the radical reduction of CO2 emissions in 2050, at least 1 billion hectares of forest would be needed to keep global warming below 1.5 degrees, the goal of international politics has settled in Paris. The new analysis shows that such a goal is “undoubtedly achievable,” notes Crowther in Science. “Forests are one of our greatest allies in the fight against climate change,” René Castro, the second man of the UN’s agricultural organization FAO, said in a response.
But in Wageningen, professor of European forestry and IPCC author Gert-Jan Nabuurs also urges caution. “This is a very important and promising publication. But I also think that these authors are somewhat positive about the effect. You might ask yourself: how realistic is all this? “Nabuurs points out that Crowther also provides forests on the tundra of Russia and Canada, where it can get tens of degrees below zero in the winter.
New boreal forests
And there is maintenance. Forest that dies again releases its carbon when the dead trees die. “There must be a certain demand for wood if you want to maintain the forest,” Nabuurs warns. “Planting trees is simple in itself. But you must have the knowledge, the nurseries, and the population to plant forest. “
Yet enthusiasm also dominates him. “In the models, we see: if you want to limit global warming to 1.5 degrees, you need to reduce emissions, but you also need carbon capture in forests,” he says. In a response, the World Wildlife Fund also stressed that forest recovery was “crucial”, and also good for biodiversity. “The next challenge is to find out where and how we can speed up implementation while we feed the growing world population,” says WWF.
Crowther also has bad news. A partial analysis shows that climate models that predict that there will be more forests in a warmer world are quite wrong. Indeed, global warming is pushing the tree line ever further north, allowing new boreal forests to grow in Canada and Siberia. But the gains do not make up for the loss of tropical jungle, note the Swiss, because the tree density there is about 60 percentage points higher than in the cool forests of the north.
Detailed maps from Crowther show that trees can also be added in the Netherlands. The Swiss see room for reforestation mainly in the Achterhoek and in the Belgian-Dutch border region.
Podcast: Does Dutch climate policy make sense?
There is a climate agreement, but does that actually make sense? Science journalist Maarten Keulemans thinks we should invest money in other countries and in innovation. That delivers more. Political editor Yvonne Hofs believes that we should also invest in the Netherlands here. In this episode of Volkskrantgeluid they talk about the usefulness and necessity of Dutch climate policy.