Els investigadors van descobrir que la Terra podia suportar 2.500 hectàrees de boscos addicionals.
I si deixem de tallar boscos per produir oli de palma i bestiar? Què passa si creem nous boscos a lots urbans buits, edificis industrials antics, fins i tot camps de golf?
Per primera vegada, els científics han volgut quantificar aquest experiment mental. Quants arbres es podrien plantar a cada parcel·la de terra disponible a la Terra , on podrien anar i quina repercussió podria tenir en la nostra supervivència ?
Van concloure que el planeta podria suportar prop de 2.500 milions d’altes hectàrees de bosc sense reduir les nostres ciutats i granges, i que aquests arbres addicionals, quan maduren, podrien emmagatzemar un munt de carboni addicional: 200 gigatons de carboni, per ser precisos: generat per l’activitat industrial durant els darrers 150 anys.
Part de l’estudi, dirigit per investigadors de l’ETH Zurich, una universitat especialitzada en ciència, tecnologia i enginyeria, es va criticar immediatament.
What if we stopped cutting down forests to produce palm oil and cattle? What if we grew new forests on vacant city lots, old industrial buildings — even golf courses?
For the first time, scientists have sought to quantify this thought experiment. How many trees could be planted on every available parcel of land on Earth, where they could go, and what impact could that have on our survival?
They concluded that the planet could support nearly 2.5 billion additional acres of forest without shrinking our cities and farms, and that those additional trees, when they mature, could store a whole lot of the extra carbon — 200 gigatons of carbon, to be precise — generated by industrial activity over the last 150 years.
Parts of the study — led by researchers at ETH Zurich, a university that specializes in science, technology and engineering — were immediately criticized.
The critics did not dispute that 200 gigatons of carbon could be absorbed by trees if you planted them on every space of land available. They disputed the implications.
The study’s authors asserted that, under their model, forest restoration could absorb two-thirds of historic emissions. Zeke Hausfather, an analyst for the climate science website Carbon Brief, said the true figure would be closer to one-third. That’s because part of the emissions absorbed by the additional trees would have been absorbed by the soil or the seas anyway.
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“That’s not to say that reforestation is not an important mitigation strategy, just to caution that like every other climate solution, it’s part of a larger portfolio of strategies rather than a silver bullet,” Mr. Hausfather said.
Pep Canadell, director of the Global Carbon Project, an Australia-based scientific group that produces global carbon budgets, said that reforestation “won’t fix the climate problem, albeit it should be part of the solution.”
The senior author of the study, Thomas Crowther, a professor of environmental systems science at ETH Zurich, did not immediately reply to an email seeking a comment.