ARR
What you need to know about ARR
- 1ARR stands for Afforestation, Reforestation, and Revegetation and involves removing CO2 from the atmosphere through forests and other woody vegetation.
- 2Afforestation is the process of foresting land that was previously unforested, and reforestation and revegetation reestablish forests and woody vegetation that had recently been damaged.
- 3Some projects mimic a natural ecosystem and others are used commercially.
- 4ARR projects can support biodiversity, healthy soil, and water.
- 5ARR generally takes place in regions where other activities like farming or logging limit forest growth.
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Afforestation, reforestation, and revegetation
ARR projects promote biomass growth that otherwise would be absent from an area with the purpose of removing more carbon from the atmosphere. ARR projects typically focus on regions where forests and vegetation have been depleted or degraded for a number of years, or building up forests in areas where forest is not the natural state.
Afforestation
Creating forest or vegetation on land that is non-forest in its natural state (like natural grasslands)
Reforestation
Re-establishment of forests on lands that have previously undergone tree-cover loss due to deforestation, land degradation, or land-use change
Revegetation
Re-establishment of other types of woody vegetation on degraded lands
As a climate solution, the ultimate goal of ARR is to enhance carbon stocks and biomass. This differs from projects whose primary goals are to reduce deforestation (such as REDD+) or to enhance sustainable management of active timberlands to grow carbon stocks (such as Improved Forest Management).
Around the world, forests contribute an estimated 7.6 billion metric tonnes of CO₂ sequestration each year — that’s about 1.5 times the annual emissions of the United States. But deforestation also contributes 11% of emissions globally, and, unfortunately, global deforestation rates are increasing. Afforestation and reforestation are important tools in greenhouse gas removal because they build forests from the ground up, introducing new biomass that otherwise would not have existed for climate change mitigation.
As a nature-based carbon removal system, ARR projects can also lead to many co-benefits for both the ecosystem and the surrounding community. If the project is appropriate to the ecosystem, using native plants and respecting existing ecologies, a host of benefits to the natural world is possible. Likewise, community engagement and capacity building can lead to increased livelihoods, more diverse crop production, and community resilience.
Forests can absorb twice as much carbon dioxide as they emit each year, making them an essential tool for mitigating carbon emissions. The trees capture and remove CO2 from the atmosphere and sequester it in biomass or soils.
What is an ARR carbon credit?
ARR credits are carbon removal credits that represent the increase in carbon stock achieved by growing new trees and forests. The climate impact of these credits can be measured and validated by developing a strong understanding of the baseline case and comparing project activities against it. That baseline scenario is a scientific assessment of how much carbon the area would remove absent the project activity. By estimating the growth rates in tonnes of biomass per year and calculating the difference, it’s possible to calculate the cumulative CO₂ stored in the biomass of the project area over time.
Baseline biomass growth for ARR projects is typically assumed to be small because the project is inherently restoring lands that have been highly degraded or used for another purpose, like agriculture. In these scenarios, forests are unlikely to occur naturally. ARR projects typically last several decades unless the gains are reversed by non-human deforestation from wildfire or pest outbreaks.
The history of ARR
In the late 1990s, efforts to stem environmental degradation, including the Kyoto Protocol and the Clean Development Mechanism, gave rise to the first carbon trading programs. This would eventually become the voluntary carbon market. The thinking was that industrialized countries that had contributed to mass deforestation could support reforestation and sustainable development goals in the countries that had seen the worst impacts. Forest carbon credits come in many forms, focusing on conservation (like REDD+) as well as afforestation and reforestation (like ARR).
As a nature-based solution, ARR has grown in popularity as a carbon credit choice for both its price and carbon-removal value. ARR is the most scaled — and often least expensive — removals option on the market. Additionally, quantification at the baselining stage is typically more straightforward than it is for REDD+ projects. That’s because the baseline is most likely to be an unforested or sparsely vegetated area without human intervention.
How do ARR projects work?
ARR projects start with the identification of an unforested area that has high potential for forest growth. Many projects or methodological standards have requirements for how long a given piece of land must have been deforested for — sometimes two or more years, sometimes 10+. In this stage, it’s important to assess the land conditions and work with local stakeholders and landowners to design a project that is appropriate for the region. Otherwise, the biomass intended to sequester carbon dioxide won’t thrive and grow into a mature forest. Nurseries also need to be established to produce trees and plants.
There are three main methodologies through which a project can establish new vegetation. The first is via natural forest growth, which is made possible by removing barriers to growth like grazing or competition with other vegetation. The second is by actively seeding or planting new trees or shrubs, and the third is an integration of the two.
ARR projects can be developed in many ways, varying in scale, purpose, and species involvement. The variety also creates multiple pathways for future use and community engagement. The more involved the community is, the more successful a project will be, particularly if the project generates sustainable livelihood opportunities. There are three main use cases ARR projects can help establish:
Enhanced forest management
The forest is planted to mimic the natural ecosystem using species that would have at one point been present. While the land isn’t used for commercial use, local communities use the forest’s non-timber ecosystem services, like food, cleaner water, fuel, and cultural values.
Commercial timber
Trees are planted and harvested on regular cycles, making use of timber for commercial use. After each harvest, the vegetation is re-established to continue absorbing carbon. Use cases for ARR in commercial timber require growing trees for active use, as opposed to IFM-type projects which adjust timber farming practices on existing, active lands.
Agroforestry
Trees are integrated into agricultural land. They provide shade for certain crops as well as products like nuts, fruits, and fuel to farmers. This also lessens the risk of shifting carbon emissions elsewhere because agricultural production is integrated rather than displaced.
What is the permanence of ARR?
In carbon credit projects, “permanence” refers to the durability of the project. How long will the carbon remain sequestered before being released back into the atmosphere, whether from natural processes or human activities? For ARR, permanence is how long the planted trees will continue growing.
The biggest risks to ARR permanence are humans reverting the area to agricultural or commercial use and disasters like wildfire or pests. Selecting project sites carefully helps mitigate the first risk. Because ARR depends on collaboration with landowners, involving key stakeholders in projects from the beginning also increases the project’s longevity as well as the co-benefits to the surrounding community.
All projects are required to complete risk assessments that evaluate the possible ways the project could fail or underperform expectations. The best projects also consider building in conservation easements or land protections to support the forests both during and after the active phase of the project. While permanence is only guaranteed during the project crediting period, legal protections can mean that the scope of impact extends beyond this, even though it’s not officially credited.
Afforestation and reforestation can also be done in areas that don’t require eliminating incentives for deforestation or competing land uses. For instance, projects that diversify livelihoods through forest ecosystem services like sustainable timber harvesting or more diverse crops are likely to have a lower risk of reversal — the risk of the carbon sequestered by the project returning to the atmosphere whether through natural or human-caused activity. For ARR projects, this can include wildfires,
The second risk — disasters — is harder to control, though in general healthy forests are more resilient to extreme events and more capable of repelling pests. Well-planned projects mitigate the risk of disasters, too, because they encourage healthier forests and better monitoring and maintenance.
ARR leakage and additionality
Leakage is the shifting of carbon-emitting activities away from the carbon credit project to another area. This shift could occur when agricultural or livestock activities are moved to another area to establish the boundaries of the carbon credit project. ARR projects are at risk of leakage for this very reason. If the land area isn’t chosen well, carbon-emitting activities will continue in a different spot. Leakage risk is lower when the project is established on unused land because there aren’t carbon-emitting activities to displace.
Additionality is proving that the project activities wouldn’t take place without the financial support of carbon markets. Usually, additionality for ARR isn’t difficult to demonstrate because the trees and vegetation would not grow in an area without the intervention of the project activities. However, if an area is used for commercial timber, it can be more difficult to both establish baselines and prove that replanting wouldn’t occur. Likewise, additionality can be harder to prove if a project overlaps with a national reforestation program. This is not typical, though.
In most areas where ARR projects are established, regenerating natural forests doesn’t make sense in the local economy without intervention. It is easier, then, to establish the financial additionality of an ARR project — proving that the activities aren’t financially viable without the support of the carbon market. Since ARR projects also stimulate sustainable livelihoods, it’s easier to encourage people to move away from unsustainable work.
Measuring and monitoring ARR carbon stock
As with any carbon credit project, establishing integrity by accurately estimating carbon stocks is essential to success and trustworthiness. The first step is to establish baselines — how much carbon was the environment sequestering without the introduction of the carbon capture project?
For ARR, the baseline level of biomass growth is generally assumed to be very low since the project establishes new growth in a previously highly degraded area. The baselines can be static or dynamic. A static baseline assumes that the pre-project status would have been very consistent, meaning that the vegetation would not have regrown without the project. A dynamic baseline continuously monitors the growth in controlled environments outside the project area with dynamic performance benchmarks.
Baselines that are only calculated once at the outset of the project — static baselines — are riskier. They might be too high or too low for future projects. Dynamic baselines are reassessed periodically and give a clearer picture of what growth outside of the project’s intervention would have looked like.
Both pre-project and project baselines are essential. That said, measuring the carbon content of an afforested or reforested area over the course of the project is more difficult than other forest conservation initiatives, like REDD+. Regrown vegetation might have very different characteristics than natural forests, whereas conserved forests are more consistent.
Co-benefits of ARR
By proactively foresting degraded or unused land to remove carbon, ARR projects are also likely to accomplish a number of other extremely beneficial things. ARR projects can restore destroyed ecosystems, providing habitats for endangered and at-risk species. They foster biodiversity and can improve air, soil, and water quality.
The project operations can generate employment opportunities for local and Indigenous communities. Projects can provide food, fuel, and timber to those communities as well. And when used in tandem with agroforestry practices, they can increase crop yields.
Ultimately, high-integrity ARR projects improve the natural landscape’s resilience. Afforested and reforested lands are better positioned to thrive amid our changing climate. Floods, landslides, and fires may be reduced or made less damaging. The land is more habitable for all kinds of life, including human. And beyond the global carbon removal provided by these projects, their local impact can be robust as well.
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While biochar has potentially high permanence — especially PAC — it is sequestered in soil. As such, both human and natural activity can cause the carbon to be prematurely released back into the atmosphere.
Biochar projects need to measure and protect against causing emissions leakage from changes in land management outside the project area, such as sourcing new biomass rather than existing stock.
Accurately estimating what would have happened to biomass feedstock in the absence of the biochar project is key to calculating the additionality of the carbon credits. Also, protecting people’s food sources from use as biomass is a concern.
Biochar has two carbon sink pools: polycyclic aromatic carbon (PAC) and semi-persistent carbon (SPC). SPC is durable for 50-100 years, PAC can persist for 1000 years in many soil types and climates.
Bio-oil and syngas are byproducts of producing biochar, and can be used to generate heat and electricity.
Biochar can be used for water filtration, as a soil amendment, or added to animal feed to reduce emissions from livestock agriculture and improve animal health.
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