Offsetting your greenhouse gas emissions can impact more than just your carbon footprint

By Tim Treuer

This Giving Tuesday, I decided to offset my 2020 carbon footprint. And help protect endangered biodiversity. And help eliminate poverty. And improve air, water, and soil quality. And support gender equality. And empower historically marginalized communities. And maybe even decrease the risk of killer diseases like COVID-19 and malaria.

But I only made one donation. And its price tag was the equivalent of about a dollar a day.

How? I’m donating to an organization that will use the funds to restore tropical rainforests. I may be biased as a restoration ecologist, but in my mind there are few ways to offset your emissions that carry as many co-benefits to nature and society as regrowing rainforests. More on that below, but first I want to address the elephant in the room when it comes to carbon offsetting: most don’t offset anything.

Seedling nursery

Per a 2016 European Commission report, 85% of carbon offsets fail to offset carbon. A big problem is scam organizations that simply do less than they promise. But even well-intentioned, reputable groups can fall short. The two main problems are failures to account for ‘additionality’ and ‘leakage’. Additionality means that the carbon that is pulled out of the atmosphere wouldn’t have been pulled out anyway. Some organizations offer to do things like establish tree plantations in areas that would otherwise be recovering forest–forest that would, in many cases, store more carbon than the tree plantation!

Leakage becomes an issue when a group’s actions to draw down greenhouse gases from the atmosphere lead to increased emissions elsewhere. This is a pernicious problem with many efforts, even ones that have huge positive local benefits. Protecting stands of old-growth forest or using farms to produce biofuels can be really great in theory, but if you don’t address the demand side of the equation, economics dictates that you’ll end up with compensatory logging or farming elsewhere. (Side note: one pet peeve of mine is that biofuel studies sometimes come up with rosy predictions because they simply assume we will produce less food and eat fewer calories in the future.)

If you pick carefully enough, however, tropical forest restoration projects often evade these two pitfalls. Many (if not most) involve jumpstarting the recovery of land that would not heal on its own because of challenges like invasive vegetation that chokes out seedlings, absent seed sources because of widespread forest clearing, or heavily degraded soils from overgrazing or nutrient depletion. So you can go ahead and tick that box for additionality. And so long as the restoration activities take place in protected settings like national parks or community forest, you shouldn’t see compensatory carbon emissions elsewhere. Ergo, no more leakage.

But carbon offsetting is only the tip of the iceberg when it comes to tropical forest restoration. Pound for pound there are more species in tropical forests than any other ecosystem on Earth. In places like Madagascar or lowland Borneo, many of those species are in serious danger of disappearing forever because of past habitat loss. We are talking millions of species hanging on by a thread. Most don’t even have scientific names yet. Their only lifeline is the resurrection of lost habitat. The biodiversity benefits of forest restoration alone can and do justify restoration projects across the tropics.

Caterpillar at reforestation site

Forest restoration through planting seedlings and controlling weeds is a super labor-intensive activity. 22-23 year old me can definitely attest to that fact after spending two seasons co-managing a reforestation project in Gunung Palung National Park on the Indonesian side of Borneo. But the required blood, sweat, and tears is a feature, not a bug. Labor means employment opportunities, and in impoverished tropical communities, that means poverty alleviation. One of the top requests from the villages where I worked was for more opportunities to be paid to reforest. And it’s equitable work too. It was common at our site to see planting teams led by women from an indigenous ethnic group– women who would be less likely to get jobs with the commercial oil palm plantations, the main local employers.

Reforestation site

There’s another reason those communities love reforestation work. They know healthy forests mean less smoke and haze from invasive grass fires, less flooding, and more consistent and cleaner water in the streams running out of the forest. The water perks span the wet and dry seasons. Forests decrease rainy season flooding via increased and root-mediated groundwater infiltration into the water table, which then feeds streams during drier periods.

At this point I’m starting to feel like Billy Mays: “But wait! There’s more!” I think it’s safe to say that most people would relish the opportunity to kick an anthropomorphized version of this global pandemic right in the nu… uhh, somewhere really painful. Tropical forest restoration is actually the next best thing. One of the big insights of the scientists in the emerging discipline of eco-epidemiology is that unhealthy ecosystems tend to yield greater risk of wildlife diseases crossing into human populations. There’s a whole slew of mechanisms for this–from stressed animals like bats shedding more virus to many malaria-spreading mosquitoes preferring open habitat to closed canopy forest– but the punchline is that when scientists looked at how to prevent the next pandemic, halving deforestation made the list of cost-effective preventative measures. My current research looks at how reforestation could protect against malaria in Madagascar, and past work I’ve been a part of showed that deforestation upstream of impoverished rural communities leads to more cases of diarrhea in kids and infants.

There are many organizations that need your support for their tropical forest restoration work, and many online tools for calculating your annual carbon footprint. I’m choosing to donate to the organization I worked with in Borneo. Not only do I know from firsthand experience that they are doing truly additional and leakage-free offsetting, but they also are super transparent about how they calculate and track their offsets.

There are tons of great organizations out there, though. You could even pick one in a country you plan on visiting once the pandemic is over– maybe they’d even show you the forest you helped replant. Just make sure you are asking three questions: will the trees you help plant cause forest clearing elsewhere? Would the replanted forest recover on its own anyway? And finally, how are they calculating their emissions reductions?

If you’re happy with your answers, congratulations! You’ve found a way to give that really does keep on giving.

Tim completed his PhD at Princeton in Ecology and Evolutionary Biology (*18), where he studied large-scale tropical forest restoration. He was a 2018 AAAS Mass Media Fellow and currently a Gund Postdoctoral Fellow at the University of Vermont, where he studies whether and how reforestation can be used as a tool for combatting malaria in Madagascar. You can find him on Twitter (@treuer) and at