How Separate Climate Targets Can Help Avoid Overreliance on Carbon Removal
The science is clear: To achieve its climate goals, the global community will need to reach net-zero carbon dioxide (CO2) emissions by midcentury. Meeting that target will require deep and rapid emissions reductions in addition to large-scale carbon dioxide removal (CDR). Activities that remove CO2 directly from the atmosphere range from natural, conventional approaches like growing trees to more novel, technological approaches like direct air capture and carbon mineralization.
CDR is necessary for meeting our climate goals, but it must complement, not replace, the steep emissions reductions that would come with switching from fossil fuels to renewable energy, electrifying transport and reducing deforestation. These efforts to reduce emissions must play by far the biggest part in reaching global mitigation goals.
Carbon removal, however, will be key to counterbalancing “residual emissions” from sources that are challenging to abate, such as some industrial sub-sectors, as well as aviation and agriculture. And once we achieve net zero, carbon removal is the only way to reduce elevated levels of atmospheric CO2 from our past emissions and reverse some of the climate-induced damage we’re already seeing at more than 1 degree C (1.8 degrees F) of warming.
Despite scientific clarity around the respective roles of emissions reduction and carbon removal in delivering a net-zero, and ultimately a net-negative future, some oil and gas companies and countries have indicated that they view carbon removal as a way to delay the urgent need to reduce fossil fuel dependence. Without strong guardrails, CDR could impede emissions reductions, a concern known as moral hazard or mitigation deterrence that is particularly relevant as countries are developing long-term plans for how to reach net zero.
Countries setting net-zero and long-term climate targets can help address this risk by setting separate targets for emissions reduction and carbon removal in the long-term strategies (LTSs) and nationally determined contributions (NDCs) they submit to the United Nations Framework Convention on Climate Change (UNFCCC), as well as for their net economy-wide mitigation targets. Clarifying CDR’s role in this way can help provide transparency and allow for scrutiny around the relative levels of both carbon removal and emissions reduction.
What Are “Separate Targets” and How Do They Relate to Carbon Removal?
“Separate targets” refers to the idea that countries, or other actors, can set separate targets for gross greenhouse gas (GHG) emissions reductions and for carbon removal scale-up by a certain year. This contrasts with the current norm of setting a single net target that combines reductions and removals into an overall number without separating their relative contributions. Separate targets can be put forward under this economy-wide target as an extra layer of specificity to provide greater transparency around how climate targets will be met and how emissions reductions and removals will be balanced to meet that target. This can help ensure that carbon removal doesn’t detract from emission reductions and avoid an overreliance on CDR.
For this reason, setting separate targets has been a key recommendation in WRI analyses on international carbon removal governance and designing net-zero targets. NGOs, academics, companies and others have also recommended this approach to enable the responsible use of carbon removal. The IPCC’s sixth assessment report also pointed to separate targets, and sub-targets for different types of CDR, to avoid substituting carbon removals for emission reductions.
Because novel, technological carbon removal approaches typically provide greater certainty of long-duration removal than conventional, nature-based approaches, some NGOs have also proposed three targets: one for emissions reductions; one for carbon removal from conventional approaches like trees and soils; and one for carbon removal from more novel approaches, such as direct air capture or enhanced mineralization. It’s important to note that many countries already distinguish between emissions and conventional removals from the land sector in their national inventory reporting, but they may not be setting a separate target for conventional removal.
This approach allows for transparency around the expected permanence, or duration of carbon sequestration, of each type of removal. It would also allow for “like for like” compensation, where removals that geologically sequester CO2, with a permanence level of thousands of years, compensate for fossil fuel emissions, which stay in the atmosphere for up to thousands of years. Simultaneously, emissions from biogenic carbon stocks like trees and soils would be compensated for by carbon removal approaches which result in storage of CO2 in biological pools.
Other proposed formulations include setting separate targets by sector, which can also provide transparency around relative levels of reduction and removal, and setting separate targets for reduction and removal in addition to complementary and more specific targets, such as reducing fossil fuel production.
Virtually all countries already communicate their emission reduction targets to the international community through NDCs every five years and through LTSs, which outline climate plans by midcentury. These commitments are useful avenues for countries to propose separate targets, especially as they increasingly express interest in including novel carbon removal in their climate planning.
Mitigation Deterrence and the Risk of Overreliance on Carbon Removal
Mitigation deterrence is the concern that the use of carbon removal can shift focus away from the urgent need to reduce GHG emissions and transition away from fossil fuels. The potential for overreliance on CDR increases this concern. More specifically, relying too heavily on CDR is risky for several reasons.
Technology development uncertainty
Carbon removal technologies are still in development, and many have not been deployed at large scale. It may turn out that they can’t deliver the expected level of removal needed, so overreliance on CDR, in place of emissions reduction, would not only mean a failure to reach CDR goals, but would also jeopardize emissions reduction targets.
Non-equivalent impacts on climate and other systems
Emitting CO2 now and removing it later is not the same as not emitting CO2 to begin with. GHG emissions can cause irreversible damage to ecosystems and human health for the time they’re in the atmosphere, particularly as we cross large-scale climate tipping points. Additionally, the environmental and social impacts of novel carbon removal approaches at scale are not yet sufficiently understood, in comparison to the well-understood net benefits of reducing emissions. Reducing emissions now can also bring different types of co-benefits, depending on the sector, like reducing air pollution and increasing biodiversity. Carbon removal processes generally do not provide a similar level of co-benefits. Lastly, one would expect a large increase in CO2 emissions and an equivalent amount of CO2 removal to have the same magnitude (though opposite directionality) of climate impact. However, research shows this is not the case, and the lack of equivalence increases as the magnitude of positive or negative flux of CO2 increases. This asymmetry in response is mainly due to how the ocean and land sinks respond to changes in atmospheric CO2.
Resource constraints
Carbon removal approaches use varying levels of resources like renewable power, land area and water, and, in some cases, materials like biomass, chemicals, steel, cement and more. Bioenergy with carbon capture and storage, for instance, can use plants grown specifically for energy, which can compete with other land uses and negatively impact food security, biodiversity, and water availability. Meanwhile, direct air capture requires a significant amount of energy. Because of these resource constraints, in addition to the limited availability of well-characterized geologic carbon sequestration capacity and geographic applicability of certain approaches, carbon removal should be considered a limited resource.
If carbon removal compensates for emissions that are not residual or could otherwise be reduced, we risk either missing our net-zero goals or needing a larger overall amount of CDR to meet net-zero goals, which would further exacerbate resource constraints. And if the limited amount of CDR available is used to compensate for so-called luxury emissions —those emissions that can otherwise be reduced — there is risk of effectively limiting the pool of carbon removal available to address residual emissions that are harder to abate. If the use of CDR is not restricted, it will be more difficult to reach net-negative emissions, as CDR is the only way to bring global temperatures back down after an overshoot past 1.5 or 2 degrees C (2.7 to 3.6 degrees F).
Separate Targets Can Address the Risk of Carbon Removal Overreliance
Setting separate targets, along with accountability mechanisms to track progress toward long-term and intermediate targets, can help address risks around carbon removal overreliance in the follwing ways.
Providing transparency
By setting separate targets, governments would communicate how much carbon removal they plan to rely on, creating transparency around the relative levels of CDR and emissions reduction. To substantiate and justify the level of planned reliance on carbon removal, governments would ideally define and quantify the levels of emissions that are very challenging to abate, due to technological or economic constraints, and would need to be counterbalanced by carbon removal. With one target, however, scenarios for reaching net-zero emissions that involve carbon removal would be treated equally regardless of whether that use is at a low or high level, despite their varying impacts on climate and other systems.
Clarifying the lack of equivalence between different types of CDR approaches
Carbon accounting today generally treats all tons equally, meaning that emissions from burning fossil fuels can be offset by carbon sequestration in biological carbon pools, such as forests. However, such an equivalence is flawed because conventional carbon removal approaches typically only sequester carbon for decades to centuries, while the CO2 emitted through the burning of fossil fuels remains in the atmosphere for thousands of years. Recognizing this disparity, there have been calls for separate targets among removals, where conventional carbon removal approaches may only compensate for land-based emissions, and novel, technological carbon removal approaches, that sequester carbon for much longer timescales (more than a thousand years), may only compensate for residual fossil emissions.
Creating policy clarity
By setting separate targets for reductions and removals, governments can send clear and actionable long-term policy signals to companies, investors, and other actors about the role of carbon removal to complement emission reductions. Such signals can provide clarity about a government’s anticipated scale-up of carbon removal and what will be required to support it (e.g., measuring, reporting, and verification systems, durable storage capacity, and renewable energy capacity to power removal facilities). Clear target setting that communicates about future capacity needs can inform near-term policy, lay the foundation for achieving long-term targets, and help ensure that CDR's likely limited capacity is allocated to the best uses that help meet those targets.
Where Separate Targets Have Been Discussed or Enacted
Separate targets for emission reductions and carbon removal have already been proposed, or put in place, at the regional, national and sub-national levels, as well as in the private sector.
Challenges of Setting and Implementing Separate Targets
While setting separate targets would reduce mitigation deterrence, clarify policy needs and illuminate the lack of equivalence both between removals and emission reductions and among different types of carbon removal, it also presents some challenges.
Defining residual emissions
To set a separate target for CDR (or one for conventional and one for novel removals), governments will need some way to determine what that target level is. One option is to estimate the expected level of residual emissions at net zero, or in a certain year, and set a CDR target equivalent to that. Some countries are already doing this by including estimations of residual emissions in their long-term strategies, while other countries may use different methods.
While tying a target for CDR to an expected level of residual emissions may substantiate a certain level of CDR, it can be challenging because there is no consistent definition for residual emissions. It is a subjective decision each country will make depending on geography, development status, politics and other factors. This makes it difficult to assess which of the residual emissions identified are hard to abate and which are inconvenient for countries or other actors to reduce. What we consider to be residual emissions will also likely decrease over time, as we develop and improve emission reduction technologies, but this can be hard to anticipate in long-term climate planning.
Of the 72 countries that have submitted long-term strategies, 26 have included estimates of residual emissions. While most industrialized countries that include these estimations project residual emissions of around 5% to 15% in 2050, countries like Canada and Australia included a much larger range of future scenarios, from 17% to 44% for Canada and 36% to 52% for Australia. Such high levels of residual emissions indicate a planned overreliance on carbon removal, representing a real risk of mitigation deterrence.
Countries could approach target setting in a different way by quantifying the level of CDR they could feasibly deploy over a certain period and set a CDR target to match that. Though, given CDR’s role as a complement to emissions reductions, it would ideally not be scaled up as much as is feasible, but as much as is truly needed.
Setting up infrastructure to support separate targets
Creating separate targets for emissions reductions and carbon removal under an economy-wide target would require separate incentives, tracking and monitoring regimes, and data reporting. Currently, the vast majority of carbon credits come from emissions reduction or avoidance, but carbon removal credits are beginning to be bought and sold as well. International cooperation via buying and selling of carbon (and carbon removal) credits is allowed under Article 6 of the Paris Agreement. Countries would need to track trading of credits against their economy-wide target, but also track progress toward removal targets for additional clarity. The IPCC provides inventory accounting guidance for emissions and land-based removals, and is developing guidance for novel CDR in the coming years.
It will also be critical to set interim targets for both emissions reduction and carbon removal to provide accountability around progress toward meeting the longer-term separate targets.
What’s Next for Separate Targets?
With the next round of NDCs due to be submitted by February 2025, as well as a renewed call at COP28 for submission or revision of long-term strategies by November 2024, countries face a pivotal opportunity to increase the ambition and transparency of their near- and long-term climate plans. In developing these plans, countries should consider the extent to which they intend to rely on carbon removal and develop separate targets for carbon removal and emissions reductions to provide transparency and ensure that carbon removal is not delaying urgently needed ambition to reduce emissions.
