Editor’s note: From “climate adaptation” to “blue carbon,” from “landscape approach" to “ecosystem services,” environmental jargon is everywhere these days. Conservation International’s blog looks to make sense of it in an occasional explainer series we’re calling “What on Earth?” 

In this installment and video, we explore "reforestation," a practice critical to stopping climate change.

What’s reforestation? 

That’s easy: It’s helping to bring forest back to an area where it was destroyed.

I have a feeling there’s more to it than that.

Well, yes: Reforestation involves indigenous peoples, wildlife, breathable air — even the cocoa powder and palm oil in your favorite breakfast spread. Fundamentally, though, it’s a matter of creating the conditions for Earth to continue supporting human life.

How is that?

Forests are the best and most cost-efficient method for removing and storing consequential amounts of climate-warming carbon dioxide (CO₂).

I’ve heard about this climate breakdown in the news. But how hot is too hot?

Glad you asked: Unfortunately, we’re well on our way to crossing that “too hot” threshold, which countries agreed to cap at 1.5˚C (2.7˚F) above pre-industrial levels in the Paris Agreement. Higher than that and things get ugly.

Oh, and we only have about a decade to stop that from happening.

What does this have to do with trees?

While it’s generally understood that fossil fuels are the leading culprit of all that planet-warming carbon, there’s a serious under-the-radar offender. In fact: It pollutes so much CO₂ that if it were a country, its emissions would rank third after China and the US.

It’s deforestation.

Really?

Really. Last year, people wiped out enough rainforests to cover Belgium. Unsustainable development and agriculture are two big drivers of deforestation, especially in developing countries.

And you may have heard of something called “imported deforestation,” which is when trees are cut down in one place — often a developing nation — to grow products such as cocoa, palm oil and rubber that are then sold somewhere else, say Europe.

Can we back up to the part about global warming? Ending deforestation is required to end global warming?

Simply put: We’ve got to stop cutting down all the trees if we’re going to stop the climate breakdown.

But even if we cut current CO₂ emissions from every source on the planet, it’s still not enough to prevent worst-case warming scenarios.

But you just said …

It turns out that CO₂ is cumulative. What humans put into the air adds to what’s already there, to what’s been there since industrialization introduced carbon-belching smokestacks in the 1880s. And because CO₂ is cumulative — and because current emissions continue unabated — atmospheric CO₂ recently reached 415 parts per million, a higher concentration than at any other point in human history.

The last time the concentration was this high, about 3 million years ago, there were trees in Antarctica — no ice caves, ice sheets, ice blocks, penguins. And zero humans.

In short: Cutting current CO₂ emissions is one requirement for a habitable Earth. Removing and storing CO₂ is another.

So, our best hope is trees?

Nature’s critical role in helping humans survive the climate crisis isn’t hope — it’s science. A recent study found that growing more forest and restoring damaged ecosystems could remove as much as two-thirds of the CO₂ that humans have been putting in the air since the 1880s.

What are we waiting for? Let’s plant all the trees!

It’s not that simple.

Nikola Alexandre, a forest restoration fellow at Conservation International, has an important point: “Bringing life back to land isn’t always about planting trees,” he says. “Nature has a remarkable ability to bounce back from disturbances on its own, especially if it’s given even a bit of support.”

This could be as simple, he says, as supporting indigenous peoples and local communities to better protect saplings from fires and hungry livestock.

So, just let nature do its thing?

Sort of. In Brazil, for example, 70 million hectares of previously forested area are degraded, 20 million hectares of which could regenerate naturally. And as Alexandre explains, natural tree growth is one of the restoration methods that removes and stores the most carbon from the atmosphere for the long term.

“Encouraging natural regeneration is much, much cheaper than planting trees,” he says. “There are certain times when it’s important to plant trees, when there is a need to have a very specific mix of species. But planting should really only occur in areas that are not going to naturally regenerate so that restoration investments can be used where they’re most vital.”

So what’s ‘restoration’?

Reforestation is an aspect of restoration. Restoration is “rewilding” interconnected systems of living Earth — and despite its name, it’s not just letting nature doing its thing. It actually involves complex, intricate science and arranging a mosaic of social and economic pieces to create the conditions by which nature can do its thing.

As Alexandre explains, “The field of restoration is, by design, about weaving people and nature together.”

So if we know what we need to do to save the planet, what’s the problem?

We’re missing some keys to success, mainly political will and alignment — and money. Large-scale restoration — what we need to keep existing forests standing and to help new forests grow — is untenable unless countries, companies and local communities are in agreement. And, ultimately, it’s going to take tremendous investment from the private sector.

The best place to start is by giving the Earth a break.

Alexandre compares the current state of the planet to human health: “Sometimes when you’re sick, you just need to take it easy, and other times, you need medicine. Thanks to us, the planet is sick right now. If we’re able to help it get some rest, a lot of the healing will happen naturally — and we can focus our efforts on healing the wounds that run deeper.”

Nikola Alexandre is a Restoration Fellow at Conservation International. Trisha Calvarese is a senior writer at Conservation International.

Further reading

• What on Earth is a ‘non-timber forest product’?
• What on Earth is a ‘carbon offset’?
• What coffee and airplanes could mean for forests