This article is a brief description of carbon offsetting through reforestation and forest protection, which are nature-based projects related to terrestrial forests. It is for someone intending to offset their carbon footprint, providing the basics for how these projects achieve carbon offsetting, what carbon accreditation auditors look at when evaluating them, and issues commonly associated with them.

For preparatory reading, and links to other articles in this Carbon Offsetting series, see articles below:

Carbon offsetting & Net Zero emissions

Since the global warming phenomenon was first confirmed in the 1990s, the need to scale back greenhouse gas emissions has been known.

Greenhouse gases have increased at an unprecedented rate in planetary history, driven by mankind’s burning of fossil fuels within a relatively short period of time. The increased heat trapped by the added greenhouse gases have begun to change the balance of climate systems, some of which lead to the release of even more greenhouse gases (e.g. forest fires, permafrost melts).

In 2015, the Paris Agreement saw the nations of the world agree that global warming needs to be kept below 2 degrees above pre-industrial global temperatures (aiming for no more than 1.5 degrees to avert the worst effects of climate change to vulnerable nations).

Net zero carbon emissions is not about that.

You may notice a growing number of companies pledging to be ‘net zero’ or have ‘net neutral’ carbon emissions. Invariably this will involve changing the way their businesses operate so that they emit less carbon. And, if there are any carbon emissions left over, they have to be offset.

However, without needing to be particularly good in math, you would realise that even if all businesses are net neutral from now on, we would still not be in carbon balance. The greenhouse gases already in the atmosphere now will continue to heat the earth, and climate change that is already underway will release other greenhouse gases from natural reserves.

So this is why I say upfront that going net zero is not about solving climate change. Additional things have to be done over and above that. Going net zero is about not making the problem worse, so that it isn’t harder and harder to solve.

Carbon offsetting verification standards

Carbon projects rely on carbon accounting to qualify as carbon offsetting. (Jargon cheat sheet article link is at the top). Like financial accounting, you need audits to make sure the carbon accounting is honest. Unlike financial accounting, which has been around for longer, carbon accounting is still being tweaked, since is it still a relatively new discipline. That this is still going on, does not mean that carbon accounting is inherently untrustworthy, or that it isn’t essential.

Carbon projects may be fully dedicated to a company intending to meet their own net neutral targets (e.g. Qantas’ reforestation project), or generate credits which can be bought by other companies or individuals like you and I. The latter are usually managed by carbon offsetting service providers, such as Terrapass.

We can rely on audits carried out by the service providers to be assured that projects are managed to standards submitted to the United Nations Framework Convention on Climate Change (UNFCCC). Examples include the Gold Standard, and the Verified Carbon Standard.

Reforestation & afforestation carbon offsetting projects

Ok, that’s the context for why carbon projects exist, and what carbon offsets are supposed to be used for. This article will cover reforestation and afforestation projects which qualify for carbon credit funding. I will also touch a little bit on forest protection projects. (Yes, they’re not the same. And yes, knowing the difference is important to be able to spot misleading news headlines. More on that later.)

Fog envelops the Nepal forest

What is the difference between reforestation & afforestation?

There are two kinds of tree planting efforts: reforestation and afforestation. Reforestation is re-planting trees on forest land. For example, Europe is replanting forests that it lost during its Industrial Age.

Afforestation, on the other hand, is planting trees on land which had a different original ecosystem (as far as we know). An example is China’s ‘Great Green Wall’ in Inner Mongolia, where forests replaced desert.

Why is it important to make the distinction? It boils down to how good an ecologist you need to be.

Reforestation is more straightforward; you know the land used to be forest. Therefore, you know what kind of forest would be appropriate for the local conditions. You know that the present day natural cycles are favourable. If you would simply abandon the human uses of the land, and maybe help it along a little bit, the forest grows back.

Afforestation requires more knowledge. This is because you’re intending to shift one ecosystem into another. Therefore, you need to study in advance what the water cycle is like, the local seasons, soil etc. This is so that you can select the right trees to plant, as well as avoid causing unintended problems, such as groundwater depletion.

How do reforestation & afforestation mitigate climate change?

Reforestation and afforestation are essential to combat climate change, because they are among the few ways we know of to absorb (“draw down”) carbon dioxide already in the atmosphere. Remember, even if everything becomes carbon neutral tomorrow, climate change will continue because of the greenhouse gases we have already released.

Like all plants, trees absorb carbon dioxide through photosynthesis. The important bit about forests, is carbon sequestration. Trees are long-lived, and convert the carbon dioxide into carbon in wood. The longer the tree survives, the longer the carbon stays out of the atmosphere. The more trees you’ve got, the more carbon you can remove and store. Reforestation alone could remove 2.7 million metric tonnes of CO2e per year.

Additionally, compared to artificial methods to remove carbon dioxide (e.g. CCS), reforestation is cheaper. It also helps to alleviate the Biodiversity Crisis through restoring habitat. The Biodiversity Crisis is a different problem from climate change. However, mitigating it makes us better able to adapt to unavoidable climate change.

If you imagine that humanity is on a runaway train, climate action is like slowing down the train. Renewing biodiversity is like making sure you still have a long, long track in front of the train!

That said, there are limits to the potential of reforestation to combat climate change. As forest ecosystems reach maturity, the amount of carbon dioxide it absorbs becomes balanced with the amount it releases through tree death and decay. At this point, it is not a carbon sink anymore. It’s just maintaining the storage of carbon. In fact, even if we save all the forests, and re-forest remaining suitable land, it’s actually not enough to meet the Paris Agreement target.

The rainforest view from FRIM canopy walkway

Which forestry projects are also carbon offsetting projects?

In general, any kind of reforestation project probably has a positive outcome. Aside from carbon capture, there are biodiversity benefits, natural resource benefits, groundwater restoration, and many more things we value from forests.

However, even though all forestry projects contribute to carbon removal, qualifying for carbon credits involves meeting specific conditions. This is because a carbon offsetting project gets to earn carbon credits. So you have to be able to say how much carbon was removed – and stayed removed – by that forest in that year.

Therefore, these need to be projects in countries where you’re fairly sure that the forest will be relatively permanent. Otherwise, buyers would be less willing to buy the carbon credits. Loss of the forest would invalidate the credits, and could mean liability to the buyer in a mature carbon trading system.

Some environmentalists see this as a weakness of counting forests as climate action. I think they are short-sighted. Their error is in assuming that all existing forest will stay as is. Therefore, the carbon capture would have happened anyway, and didn’t need the carbon offset funding. But in many parts of the world, the trend is deforestation due to economic pressures.

View of the Bukit Nanas forest from the KL Forest Eco Park canopy walkway

US style corporate management promotes senior managers who see staff in terms of their job grade, like parts in a machine. So if two people happen to be in the same job grade, therefore they must be interchangeable.

As a kind of LOTR fan, I have to nitpick the phrasing and clarify that the reason why the One Ring was the least dangerous with a hobbit, is because hobbits just want to live life and get along, ie hobbits aren’t tempted to “rule them all”.

Clean Development Mechanism (CDM) methodologies for reforestation & afforestation

Credible carbon offsetting certifiers generally refer to methodologies submitted to the UNFCCC. For reforestation and afforestation projects, there are methodologies for large and small scale forests. They are broadly similar; the small scale ones are simpler.

Unlike carbon offsetting projects which are engineered, or contained on-site, nature-based carbon offsets such as forests are more complex. This is because natural ecosystems respirate, storing carbon (‘carbon sinks’) but also releasing it (‘carbon sources’). Forests are only considered carbon sinks because, on balance, they store more than they release.

Therefore, reforestation methodologies rely on estimating the difference in forest biomass. That increase, if any, is what generates carbon credits from that year.

Reforestation methodologies also set criteria to determine whether the tree planting project is additional or not. In other words, ‘would forestry have been a plausible land use after all if there was no carbon project’? In order to qualify for carbon credit funding, the project needs to show that there is land use pressure, and that a reforestation project is unlikely to be the future land use.

Complete Guide to Taman Negara, The World's (Almost) Oldest Rainforest! - guide article on the sustainable travel blog Teja on the Horizon | view down a tributary within a Malaysian rainforest national park

What is the difference between reforestation & forest protection?

Forest protection is not a tree planting project. Rather, it is about preventing existing forest from being cut down in the first place.

Reforestation and afforestation are more straightforward. The land isn’t currently forest; the project is about growing forest on it.

On the other hand, preventing deforestation has a different baseline, in ecological terms as well as economic terms. The concept is simple. But since a carbon project needs to show that the forest was at risk without the carbon offset funding, this type of forestry project is much more ambiguous.

Are projects preventing deforestation part of carbon offsetting?

Yes, but it’s under the REDD+ program. To understand why REDD+ exists in the first place, you need to understand the earliest debates on climate and environmental justice.

REDD+ stands for ‘Reducing Emissions from Deforestation and Forest Degradation in Developing Countries‘. Natural ecosystems face a lot of land conversion pressure in less industrialised countries. If developing countries develop along the same path taken by Europe and North America, more forest and other resources have to be harvested, before restoring some of it as Europe and China are currently doing.

On the other hand, if we don’t industrialise, we face climate change without the technology and economic base to adapt to it, magnifying human suffering. This is why forest protection in developing countries is not a simple matter of just gazetting it, like in developed countries. It often involves a great sacrifice.

Unfortunately, the world cannot afford to give us that development path. Global warming is already well underway; all of our forests must remain intact to save life on earth. Simply leaving our forests alone contributes 3,124 million metric tonnes of CO2e per year. Improving its management is worth an additional 820 million metric tonnes per year. It blows the full potential of reforestation out of the water.

Because of this context, REDD+ projects are typically in developing countries. The framework (the Warsaw Framework) came about after COP19 negotiations in 2013.

What is the difference between REDD+ vs. reforestation carbon credits?

Reforestation and afforestation generate carbon credits in the same way as any other carbon offsetting project; i.e. carbon credits are issued based on the amount of CO2e avoided or removed by the project. (Incidentally, this means that once the forest matures, it may no longer generate credits.)

REDD+ projects tend to cover mature forests, or nearly-mature forests. The objective is not so much about increasing carbon sink capacity, but about not losing it. Consequently, REDD+ projects are about validating forest management, proving continued carbon sink/storage status. The funding mechanism is tied to this performance.

Can I buy REDD+ credits on the voluntary carbon market?

Yes, it’s possible. For example, some VCS forestry projects are REDD+ projects, and Shopify’s carbon neutral shipping option is partially compensated through a REDD+ project.

However, REDD+ governance does tend to have more uncertainty, both because the baseline is less clear (to calculate how much carbon emissions was saved), as well as the country politics. Unsurprisingly, development and land use competition can be very political.

For this reason, some voluntary offsetting providers do not issue REDD+ credits at all. Remember that the role of voluntary offsetting is to speed up carbon projects. It makes more sense for them to focus on projects that are more certain.

This does not mean that REDD+ projects are not important. We would stand to lose a great deal of forest if that were the case. For this reason, some voluntary offsetting providers take more risk to accredit these developing country projects, like Verra.

The risk is real, as Verra discovered when it found that its REDD+ accreditation approach had substantial loopholes. So, while you can buy REDD+ credits, it’s also understandable if you opt to avoid it until a robust means to audit it can be devised, and support forest protection separately (e.g., through biodiversity efforts rather than climate).

That said, by this point I hope you are equipped to notice that, in reporting this expose, many corporate media make it appear as though Verra’s doubtful credits is reflective of all forestry projects, and all carbon offsetting projects, even though they were all related to REDD+ projects. Whereas when you understand the context, it’s clear why REDD+ projects exist and are an important part of climate justice, but are simultaneously also more ambiguous and unlike other forestry projects. I leave you to reflect on why the scandal was covered in such a misleading way.

What are the challenges in measuring carbon offsets from planting trees?

A major consideration for forestry projects, is the issue of leakage. Since projects receive carbon funding because there are competing land use possibilities, the project has to account for whether it displaces another activity. For example, if the project is about reforesting grazing land, then it must document what happened to the grazing activity. If it simply moves to deforest another piece of land, then the project does not qualify.

Leakage doesn’t mean that a reforestation project can’t proceed. However, if the displaced activity moves to another site, and results in increased carbon emissions, then the forestry project has to account for that. Credits would only be issued for the net emissions removal.

Even so, personally I still prefer tree planting projects which are carbon offsetting projects vs those which are not, precisely because leakage accounting is part of the methodology, unless there are no competing land uses anyway. Without leakage accounting, you may only have a feel-good project.

Another important consideration for reforestation projects, is soil disturbance. This is because there is often a lot of carbon stored in soil. Disturbing it exposes this carbon to the atmosphere, and kicks off processes that release greenhouse gases. Therefore a reforestation carbon offsetting project has to limit soil disturbance. Some types of land wouldn’t even qualify because of this.

This is another reason why I prefer tree planting projects which are carbon offsetting projects. The methodology helps to ensure that the benefit is real.

Taman Negara trail

If a carbon credited forest burns down, what happens to the carbon credits?

This is a fairly common misgiving at the back of our minds. Let’s say you bought carbon credits from a forestry project, but the forest burns down or is cut down. After all, global warming itself will make forest fires more likely in many locations. And let’s not talk about countries where even permanent reserve forests are constantly in danger of urbanisation.

Would you lose your carbon offset? Do you have to replace the credits? How would you even know this happened?

Why environmentalists should learn other disciplines

To be honest, I was never truly worried about this. I didn’t worry because, even though I’m an ecologist by training and an environmental scientist by profession, I understand other disciplines like finance and insurance. I know that there are tools we can adapt in these professions to provide risk hedging in carbon finance. Yes, it will take a while until the actuarists figure out how much to hedge, given the novelty of the instrument and the risks. But surely it is only a matter of time.

And indeed, that’s exactly what is happening. For example, VCS requires all such projects to ‘pay’ extra offsets into an insurance/buffer pool. In other words, for a given amount of carbon credits the project generates, it has to put in some into this buffer pool. How many depends on the project’s risk, similar to how an insurer comes up with your insurance premium. Projects managed under the same provider therefore insure each other.

So let’s say something happens to the stored carbon. One of the forests burn down within the crediting period. The carbon offsetting provider can cancel an equivalent amount of buffer credits to account for the reversed offset. This approach is becoming more widely adopted.

I’m not sure whether Verra’s problematic REDD+ credits were fully covered by their buffer, but at least it partially would be. The experience would adjust the estimate of risk for such project types, and a larger buffer raises the price of the credit to account for the risk. That is actually what’s meant to happen.

Further reading:


I would like to acknowledge Gold Standard and Verra for responding with information and resources that facilitated the writing of portions of this article.

An important part of the Paris Agreement is recognition that countries must have the freedom to choose the combination of methods for how they meet their climate ambitions, because each nation has vastly differing circumstances. A solution that doesn’t make sense to one country – however large and influential – may be perfect for another. Would forests in your country be saved if they were carbon projects?

Article explaining how to understand forestry types of carbon offsetting projects

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