WEBVTT - How Many Trees Would We Need to Plant to Slow Climate Change?

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<v Speaker 1>Welcome to brain Stuff. Production of I Heart Radio, Hey

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<v Speaker 1>brain Stuff Lauren vog obamb here. In recent years, climate

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<v Speaker 1>change has loomed like a dark specter over the globe,

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<v Speaker 1>contributing to everything from gentrification in Miami is high income

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<v Speaker 1>coastal dwellers seek new residents fur their inland away from flooding,

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<v Speaker 1>two refugees fleeing drought and crop shortages in Guatemala. But

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<v Speaker 1>the urgency around the issue reached new heights in the

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<v Speaker 1>United Nations. Intergovernmental Panel on Climate Change or IPCC stated

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<v Speaker 1>that rapid, quote, far reaching and unprecedented changes in all

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<v Speaker 1>aspects of society would be needed in order to drop

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<v Speaker 1>carbon dioxide levels by and prevent catastrophic global warming. Scientists

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<v Speaker 1>have indeed proposed drastic measures, just not the way that

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<v Speaker 1>you might think. In the same i p c C report,

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<v Speaker 1>the u N suggested that adding two point five billion

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<v Speaker 1>acres that's one billion hectares of forest to the world

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<v Speaker 1>could help limit global warming in future decades to just

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<v Speaker 1>two and seven degrees fahrenheit that's one point five degrees celsius,

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<v Speaker 1>which would stave off some of the worst effects of

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<v Speaker 1>climate change. And now the U N might just have

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<v Speaker 1>the data to back up their proposal. In another study

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<v Speaker 1>unveiled in July of twenty nineteen and the publication Science,

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<v Speaker 1>a group of researchers associated with the Crowther Lab in

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<v Speaker 1>Switzerland found that global tree restoration to the tune of

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<v Speaker 1>nine hundred million acres that's point nine billion hectares of

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<v Speaker 1>canopy cover, an area that's approximately the size of the

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<v Speaker 1>United States is quote our most effective climate change solution

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<v Speaker 1>to date. That would require upwards of half a trillion trees.

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<v Speaker 1>These trees would store two hundred and five billion tons

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<v Speaker 1>of carbon, or roughly two thirds of the carbon that's

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<v Speaker 1>been omitted by we humans since the Industrial Revolution. Some

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<v Speaker 1>news reports said that this much forest restoration is the

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<v Speaker 1>equivalent of roughly one trillion trees, but that statistick is

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<v Speaker 1>from an estimate in a report from but we spoke

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<v Speaker 1>with the current studies lead author Jean Frascois Bastin via email.

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<v Speaker 1>He said the idea was to estimate what tree cover

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<v Speaker 1>could be expected when you removed the human factor, i e.

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<v Speaker 1>What specific types of forest would naturally occur in the

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<v Speaker 1>absence of other development and where. The team used the

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<v Speaker 1>form of artificial intelligence known as machine learning to build

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<v Speaker 1>quote a model to link tree cover with climate, soil

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<v Speaker 1>and topography based on seventy eight thousand observations of tree

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<v Speaker 1>cover in protected areas. The researchers then projected the data

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<v Speaker 1>further to estimate the potential total tree cover of the

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<v Speaker 1>whole planet if human civilization didn't exist. But of course

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<v Speaker 1>humans do exist, so the team then excluded land currently

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<v Speaker 1>being used for urban settlements, crop lands, and existing forests,

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<v Speaker 1>which yielded the total amount of land available for restoration.

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<v Speaker 1>The study offers a map showing how much tree coverage

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<v Speaker 1>different parts of the globe might support, the top three

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<v Speaker 1>areas being Russia, Canada, and the United States. The studies

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<v Speaker 1>timing a lines of current global efforts around ecological rest ration.

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<v Speaker 1>A one example is the Trillion Trees Vision, which seeks

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<v Speaker 1>to restore one trillion trees by fifty Another is the

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<v Speaker 1>Bone Challenge, which is a partnership between the Government of

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<v Speaker 1>Germany and the u n's International Union for Conservation of

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<v Speaker 1>Nature that aims to restore three seventy one million acres

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<v Speaker 1>of deep forested land by which is about of the

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<v Speaker 1>current studies recommendation. You might be thinking, well, that sounds

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<v Speaker 1>pretty easy. Let's all roll up our sleeves and save

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<v Speaker 1>the planet by planting one tree at a time, right,

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<v Speaker 1>But some experts say the situation is actually a little

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<v Speaker 1>more complicated than that rosy picture, especially if most nations

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<v Speaker 1>don't chip into help. Although by fifty eight nations had

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<v Speaker 1>banded together to commit an acreage that would exceed the

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<v Speaker 1>BONB Challenge goal, most of the restoration work to date

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<v Speaker 1>has been done by only a few countries. We also

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<v Speaker 1>spoke with Jim Hallett, chair of the Board of Directors

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<v Speaker 1>for the Society of Ecological Restoration. He cited major challenges

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<v Speaker 1>to implementing restoration on such a global scale, quote including financing, governance,

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<v Speaker 1>land tenure and ownership, and capacity to do the work.

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<v Speaker 1>There's ample evidence that in some contexts, if the benefits

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<v Speaker 1>of restoration are not equally shared, the project will fail.

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<v Speaker 1>So incentive programs have to be carefully developed, and restorational

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<v Speaker 1>loan will likely not be enough. It takes time, after

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<v Speaker 1>all to implement such a big restoration projects, and also

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<v Speaker 1>for these trees to store carbon, and how it stresses

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<v Speaker 1>that we have to not just restore previously forested lands,

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<v Speaker 1>but preserve what we've currently got. Other scientists question not

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<v Speaker 1>only the practicality of the studies claims, but also the

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<v Speaker 1>studies very methodology. But we spoke with Ica Liling, climate

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<v Speaker 1>change researcher and professor of horticultural sciences at the University

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<v Speaker 1>of Bonne. He pointed out that some of the areas

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<v Speaker 1>marked for restoration couldn't support more trees than they already do.

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<v Speaker 1>Some of them are in permafrost regions for example. Also

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<v Speaker 1>quote the methodology implicitly, probably not on purpose, implies that

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<v Speaker 1>carbon stock is portional to canopy cover i e. Ecosystems

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<v Speaker 1>without trees contain no carbon. This is clearly false and

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<v Speaker 1>strongly inflates the global estimate of restoration. Young Barner, Leedling's

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<v Speaker 1>colleague and a professor for economics of sustainable land use

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<v Speaker 1>at the University of Bonne, is similarly skeptical. Barner says

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<v Speaker 1>that some of the areas being proposed for restoration under

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<v Speaker 1>the current study are already in use for other purposes.

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<v Speaker 1>Barner considers the study to be a quote interesting academic exercise,

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<v Speaker 1>but as a climate change mitigation strategy proposal, and it

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<v Speaker 1>is being advertised as such, it sends a misleading signal

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<v Speaker 1>to the international climate policy debate, but don't fret. Both

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<v Speaker 1>Bustine and Hallett emphasize that the u N has declared

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<v Speaker 1>thirty the Decade on Ecosystem restoration, which could spur nations

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<v Speaker 1>to act quickly, and some countries are already tackling the

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<v Speaker 1>initiative head on. And according to Hallett, forest restoration boasts

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<v Speaker 1>far more perks than just impacting climate change, including maintaining

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<v Speaker 1>or even increasing bio diversity and preserving the ecosystem that

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<v Speaker 1>we humans rely upon for our food and water. But

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<v Speaker 1>even the studies authors acknowledge that it's going to take

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<v Speaker 1>a lot of goodwill to make this grand vision of reality.

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<v Speaker 1>Bastine said, what we need is a universal action. International

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<v Speaker 1>agencies and geo's governments all citizens anyone can be involved.

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<v Speaker 1>Local communities and small organizations may be especially effective. While

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<v Speaker 1>they do not have the same reach as national agencies,

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<v Speaker 1>they have the benefit of knowing what works best in

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<v Speaker 1>their own backyards. Today's episode was written by Terry our

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<v Speaker 1>Lagata and produced by Tyler Clang. The brain Stuff is

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<v Speaker 1>in this and lots of other topics for everyone to

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