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Forests devouring CO₂

Planting trees can play a huge role in limiting the impact of climate change, thanks to their capacity to absorb CO₂.

by Eni Staff
03 February 2020
6 min read
by Eni Staff
03 February 2020
6 min read

Main aim: new tropical forests CO2

A new study by ETH Zurich, published in the magazine Science, states that about 900 million hectares of land around the world, about the size of the United States, could be reforested, absorbing about two thirds of the carbon produced by man since the industrial revolution. The study excluded cities and agricultural areas. Professor Thomas Crowther, co-author of the study and founder of the Crowther Lab at ETH, in Zurich, explains: “We all knew that restoring forests could play a huge role in fighting climate change, but we didn't know just how great its impact could be. Our study clearly demonstrates that restoring forests le is the best solution there is for tackling climate change. But we must act quickly because the new forests will take decades to grow and reach their full potential as storers of natural carbon.” Unsurprisingly, the countries most suited for reforestation are also the largest: Russia, the United States, Canada, China, Brazil and Australia. Nonetheless it is important that they are reforested, above all in tropical areas, because there trees can grow more quickly and consume more CO2, and because the tree cover in those regions' forests is 90–100%, compared to 30–40% in northern forests.


Drawbacks of reforesting

Besides absorbing CO2, forests have various other environmental strong points, like reducing the risk of drought, floods and soil degradation, and improving the quality of air and water. Writing for the World Economic Forum, Crowther explains that all the other solutions put forward for decreasing emissions, “from electricity generation, to transport, food, education and land use – have one thing in common: primarily, they only prevent future emissions. To stop climate change, we must draw down the carbon already emitted into the atmosphere. [...] Ecologically speaking, trees are the most effective means to capture and store carbon.” The study is encouraging, but many experts say that simply planting trees is not enough to fight climate change. In a comment added to the article in Science, Robin Chazdon, a member of the department of ecology and evolutionary biology at the University of Connecticut, writes that “the numbers certainly represent the maximum possible, but they will not be easy to reach.” An earlier study suggests that “the power from biomass plantations needed to significantly mitigate our carbon dioxide emissions is staggering and would demand unsustainable human and environmental costs.” Already overburdened ecosystems would be further threatened, transforming great strips of natural landscape into biomass plantations, while planting trees in arable land makes it even harder to feed a constantly rising world population. Furthermore, if fertilisers are used to help trees grow, they themselves release greenhouse gases into the atmosphere. Plantations could also put more pressure on already scarce water resources. Clearly, planting trees could be “the most important and cheapest tool” for fighting climate change, but it is not the only one. The simplest and most urgent measure is to arrest the deforestation going on in the Amazon, Africa and Asia. According to the Carbon Disclosure Project (CDP), around 5 million hectares of forest are destroyed every year. As Faye Flam, a Bloomberg columnist, writes, “The buildup of greenhouse gases is simply too big of a problem to be solved by one course of action alone, whether it’s increasing the use of solar energy or giving up beef or capturing carbon from the atmosphere. A recent estimate that planting lots of trees could soak up most of our excess carbon is, unfortunately, a little too good to be true.”

The long and winding road to zero emissions

Professor Myles Allen, who lectures on the science of geosystems at Oxford University, adds: “Restoration of trees may be 'among the most effective strategies', but it is very far indeed from 'the best climate change solution available', and a long way behind reducing fossil fuel emissions to net zero. Yes, heroic reforestation can help, but it is time to stop suggesting there is a 'nature-based solution' to ongoing fossil fuel use. There isn't. Sorry.” Other measures, like decarbonization of energy, transport and heating and air-conditioning systems, as well as reducing meat consumption, are equally important. It is crucial that major reforesting programmes are not used as the only measure to reduce carbon, but married with others to produce fruitful results.

The Indian beech: an extraordinary plant

One plant is not the same as another. Some plants, like clover or beans, are known for their ability to put nitrogen back into degraded soil. But none of them compare to the Indian beech (Millettia pinnata), a tree from Asia. A frequenter of degraded and marginal soils, it is the perfect candidate for reforesting where other plants cannot grow, as it needs little water and produces seeds rich in oil (up to 40%) and protein. In its ability to trap carbon it also beast other species; the Indian beech traps more CO2 than it emits, and given that its oil is a natural fungicide and insecticide, the plant needs minimal protection, if any, from parasites. As a plant grown for oil, requiring low maintenance and low water consumption, not grown for food, with a high yield and restorative properties, the Indian beech is also the perfect raw material for biofuel. India is already doing successful reforesting projects using the eponymous beech.

Apple plants mangroves in Colombia

Apple has announced it will be investing a project to recover mangrove forests along the Colombian coast. Carried out in collaboration with the NGO Conservation International (CI), the project mainly covers the mangroves along the river Sinú, an area on which about 12,000 depend for their living, thanks to its wood, food and raw materials. This region is currently in trouble and the local people need the economic certainty they can only get from fishing and tourism. Apple's initiative will help them carry out this project with the help of Conservation International. Besides planting new trees in degraded areas, the recovery project will conserve existing trees, restoring mangroves in an area of forest of 11,000 hectares, which will absorb up to 17,000 tonnes of CO2 from the atmosphere in two years. This is the equivalent of the carbon dioxide that will be produced by all the vehicles collecting information for Apple Maps over the next ten years! Throughout their lives, the restored mangroves will absorb more than 1 million tonnes of CO2 emissions.