As technological carbon removal has garnered widespread attention, one response resurfaces repeatedly: Why complicate climate solutions with expensive, experimental technology when Earth’s most efficient carbon removal machines already exist in nature? Why not just plant more trees?

While we understand the uncertainty that comes with any burgeoning technologies, it’s risky to paint any approach (even trees!) as a silver bullet solution. In fact, an oversimplified “this-or-that” mentality can do more harm than good — it shuts down nuanced conversations, ignores the complexity of different CDR pathways, and pits tech- and land-based solutions against each other. In reality, we’ll likely need a combination of tech, land, and cross-solution pathways to achieve necessary gigaton-scale removals by mid-century.

First, the merits of forestry approaches

It’s true that forests are valuable carbon sinks — trees can remove and store huge amounts of carbon for decades to centuries, and US forests alone capture nearly 12% of national annual emissions. If expanded and restored at scale, US forests could remove nearly 700 million tonnes of carbon dioxide per year for as low as $5 per ton.

On top of their carbon-storing power, forests provide a wide range of benefits that serve community health, local economies, and climate resilience needs. These myriad benefits make forests key to meeting equitable carbon removal goals, supporting a strong case for their protection, restoration, and sustainable management.

But scaling up tree planting is no easy feat

New research revealed that US nurseries face a serious shortage of tree seeds and seedlings, a limiting factor in ramping up reforestation. To replant about half of the total reforestable area in the US by 2040, the study estimates that nurseries would need to produce an additional 1.7 billion seedlings per year — 2.3 times the current rate of production.

The scarcity of seedlings presents a real challenge, but it’s not just about seedlings — it’s also about people. The same study found that only 32% of nurseries currently produce at full capacity, citing workforce shortages as the greatest barrier to expansion. Specifically, nurseries depend heavily on a seasonal migrant workforce, and survey respondents cited immigration policy as their single largest concern.

Forest carbon removal also raises complex land use concerns, as many of these approaches require large swaths of arable land. Planting can intensify competition with other uses like agriculture or depend on land that is not suitable for long-term carbon storage under a changing climate. The way we reforest is key — the site, scale, and mix of tree species must be selected to protect whole ecosystems and the services they provide.

A disproportionate dependence on forest carbon removal

Our exploration of carbon offsets highlighted the blurred line between removals and reduction efforts in forestry projects, undermining the quality of these offsets and their total carbon impacts. Most corporate, national, and international emissions targets depend on forests to meet climate goals, but these projects depend on a handful of carbon accounting assumptions that, in many cases, overestimate the carbon stored in forests and perpetuate global injustices.

Carbon equivalence

Land-based pathways are used to offset emissions from fossil fuels, assuming all forms of carbon are equivalent when, in reality, they are not. Fossil carbon trapped underground naturally cycles much slower than biotic carbon found in forests — fossil carbon can stay put underground for hundreds of millions of years, while forest carbon turns over every few centuries. This million-fold difference reflects that there is simply a lot more carbon stored in fossil reservoirs beneath the Earth’s surface (aka millions of years worth of sedimentary rock) than in forest ecosystems. The assumption of carbon equivalence ignores these enormous differences in both pace of carbon cycling and the size of these natural reservoirs.

Atmospheric carbon can re-enter either carbon cycle. However, the different timescales and sizes of these cycles can help us rethink how to depend on different carbon removal pathways.

Because they belong to this shorter-term, smaller-scale carbon cycle, forest carbon sinks have finite capacity that reflects losses over time, primarily due to disturbances like land use change. In other words, planting trees restores carbon that forest ecosystems have already lost — but this restoration can’t account for the vast amounts of carbon humans have released from fossil sources, which took millions of years to accumulate underground.

Geographic equivalence

Carbon removal solutions (and climate action in general) typically work under the assumption that the specific site of removals or emissions doesn’t matter because carbon dioxide is diffused equally across the Earth’s atmosphere. This assumption of geographic equivalence allows wealthy countries and corporations to finance removal projects elsewhere to meet emissions targets in an international exchange of mitigation responsibilities. The exchange usually includes Global North countries paying for forest offset projects in the Global South — a system of transactions coined by some as carbon colonialism.

Pursuing large-scale forest carbon removal requires governance frameworks that protect the livelihoods and well-being of vulnerable communities. While some geographies are simply more suited to certain types of carbon removal, project developers can’t ignore the complex social, political, and cultural factors for communities that exist within those geographies. Forest carbon removals must not come at the expense of communities’ access to and sovereignty over ancestral forests, key natural resources, and economic vitality.

No silver bullets

While forestry is a key piece of the complicated CDR puzzle, it’s no silver bullet — no solution is. We are in the midst of a climate emergency and need to deploy all solutions at our disposal. We should view different approaches as additive and complementary in the solutions landscape, each with unique merits, opportunities, and restraints.

Many forestry approaches are shovel-ready today and can be fully realized with policies that support carbon removal, community well-being, and ecosystem resilience. Here are five key recommendations to support an equitable and durable scale-up of forest carbon removal.

1. Increase investments across reforestation activities to ensure that regional seedling supply can meet accelerating planting demand.

USFS should address the backlog for replanting public lands, as outlined by the REPLANT Act. The government should also expand investment in public and private nurseries to address the national seedling shortage, as outlined in the SOS for Seedlings Act.

2. Expand and create new federal corps programs to support job creation and workforce development in forestry within vulnerable and underemployed communities.

Developing local expertise and workforce capacity in forest stewardship and climate mitigation will support long-term community resilience and economic diversification. The Public Lands Corps, AmeriCorps, and Job Corps should reorient to prioritize forest restoration and management projects, tailoring programs to meet local community employment and ecosystem needs. A new Civilian Climate Corps could serve as an important workforce development opportunity, building on President Biden’s recent executive order.

3. Advance forest carbon monitoring, reporting, and verification (MRV) technologies and approaches.

Robust MRV will be critical to accurately measure how much carbon is stored in forests across geographies, species, and management approaches. Combining high-resolution remote sensing, field data, and modeling can help improve these efforts, given the growing interest in monetizing forest carbon.

4. Explore policy options to separate land-based and fossil-derived carbon accounting to reflect their different carbon sinks and cycling rates.

Policy can lay the groundwork for regulating carbon removals by sector, e.g. land-based removals for land-based emissions and technological removals with geologic storage for fossil emissions. By limiting cross-industry reliance on land carbon removal, this transition would spur innovation in tech CDR and emissions reductions efforts to decarbonize industries dependent on fossil fuels.

5. Increase international collaboration to support equitable and global scale-up of carbon removal.

The government should support efforts that promote international collaboration and provide technology, information, and funds to Global South countries for carbon removal RDD&D. The US should work to ensure that Global South countries have the tools and autonomy to make decisions about the suite of carbon removal projects they want to see deployed on their lands.

Alongside robust and justice-oriented tech CDR policy, these recommendations can support a multi-pronged approach to carbon removal, maximizing the carbon impacts of each pathway while supporting an equitable transition.

Image: Ben Neale