But Planting Trees is Useless, Right?

Could Afforestation Be a Tool to Cool Down Global Warming?

My husband was born in Colombia, and his first language is Spanish. I was born near Barcelona, in Catalonia, and although I also speak Spanish like a native, my first language is Catalan. We live in the United States, where our children were born.

They are 2 and 4 and have already experienced what it is like to grow up in a trilingual household.

My husband and I value our mother languages very much, and we were very concerned that our children would not learn them at a proficient level that would allow them to communicate effectively with our families back home.

So, what did we do?

From day one, we talked to them in our respective languages—always, no matter what. English wasn’t an option. In fact, English was banned from the house unless we had guests. They are learning English at school. On top of that, we read to them every single night in our respective languages.

Some might say that one single story won’t make a difference, but when you put over four years of stories and conversations together, you get trilingual kiddos that surprise all your friends when you visit for the holidays. Compounding effect in action!

Is that applicable to anything else? What would happen if we started planting trees systematically? Would the compounding effect make a difference when it comes to climate change mitigation?

When it comes to tackling climate change, planting trees — whether through afforestation or reforestation — has often been highlighted as a potential solution. But how effective can it really be on a global scale? Can we even scale it up enough?!

A recent study led by Dr. Yiannis Moustakis and Dr Julia Pongratz provides new insights into this very question. The research, published in Nature Communications, a prestigious science journal, explores how large-scale tree planting could significantly lower global temperatures and shorten the period of temperature overshoot beyond the 1.5-degree target of the Paris Agreement.

Afforestation and reforestation (AR) are currently the most widely applied methods of removing carbon dioxide (CO₂) from the atmosphere. That’s why you have probably heard plenty from them over the years.

In this study, the researchers set out to see how an ambitious AR strategy might impact global temperatures. With worldwide pledges aiming for up to 490 million hectares of AR by 2060, and likely more in the future, the study sought to estimate how much these efforts could curb climate warming. Will there be effective?

To do this, the team developed a scenario anticipating 595 million hectares of AR by 2060 and 935 million hectares by 2100. Dr. Moustakis described this as “definitely an ambitious scenario,” noting that the aim was to develop a plan “rather in the range of country pledges globally” while balancing technical feasibility, economic constraints, and minimal biodiversity impacts.

To analyze the potential impacts of this extensive AR, the team used a comprehensive approach, bringing in over 1,200 scenarios from Integrated Assessment Models (IAMs). These models blend various factors, from climate policies and energy pathways to economic and land-use changes.

The researchers also incorporated restoration priority maps and biodiversity considerations to develop their ambitious AR scenario. This balanced approach ensured they accounted for technical and economic challenges, as well as the impact on biodiversity and land availability.

I know it is a very complex and well-thought-out design. Kudos to the amazing researchers; I know all too well how hard these studies are.

Once they had their scenario, they ran simulations using the Max Planck Institute for Meteorology’s Earth System Model. They adopted an “overshoot scenario,” where global temperatures initially exceed the 1.5°C goal before dropping back down around the end of the century.

This model is particularly relevant given the current delays in strong climate action, which make such temperature overshoot pathways increasingly probable.

And what did they find? Well, the simulation results were promising.

The ambitious AR scenario showed the potential to reduce peak global temperatures by 0.08°C and lower end-of-century temperatures by 0.2°C. Additionally, it could shorten the time that global temperatures exceed the 1.5°C target by 13 years, with the effects becoming noticeable as early as 2052.

But there’s more to it than just cooling down the planet. AR can also alter the physical properties of the Earth’s surface — think changes in how much sunlight is reflected (albedo) and how water evaporates from the ground.

I know it sounds like science fiction, but it’s just science!

In fact, these shifts can cause local warming in some regions. However, the study found that the overall cooling effect from carbon sequestration far outweighed any warming caused by AR itself.

“The cooling effect of CO₂ absorption predominates,” Moustakis explains, meaning the benefits of tree planting still stand strong even when these side effects are considered.

So, what does this all mean for climate action? The study highlights that AR can play a key role in global efforts to mitigate climate change. However, it’s not a one-size-fits-all solution and comes with its own complexities and potential trade-offs.

For example, afforestation can bring economic and social benefits like job creation, ecosystem services, and revenue generation. On the flip side, though, large-scale tree planting might displace people, disturb local food systems, and potentially increase poverty if not implemented carefully. Things need to be evaluated very carefully so that the solution isn’t worse than the problem.

In short, the findings suggest that afforestation and reforestation efforts could make a valuable contribution to reducing global warming. The potential to cut peak temperatures and reduce the duration of temperature overshoot is significant, especially when coupled with other measures to cut emissions.

However, it’s clear that implementing these actions will require a careful balancing act, considering not just the environmental benefits but also the socioeconomic impacts.

Afforestation is no silver bullet. But with careful planning and execution, it could become a vital part of our strategy to cool down the planet and achieve long-term climate goals. And as the research shows, every fraction of a degree counts in the fight against global warming. Could we make this count, too?