Getting to net-zero using carbon-negative options: What to do with forest offsets?

Carbon removal may be needed to get to climate targets

Global warming presents significant risks to our wellbeing in the long run, prompting the world to see temperature targets.[1] To get to the ambitious 1.5C global warming target set at the Paris Conference of Parties (COP) in 2015, we need to get to net-zero carbon emissions by 2050,[2] where net-zero pertains to the difference between carbon emissions and carbon removal getting to zero.

One way to get to net-zero is to simply reduce carbon emissions to zero without the need for carbon removal. As many studies show, this is technologically possible.[3] However, for many sectors (e.g., industry and long-distance transport), cost-effective technologies do not yet exist, which makes getting to net-zero an expensive proposition that businesses may shy away from.[4]

Carbon removal options include direct air capture as well as forest offsets

This has brought the discussion of carbon removal options to the forefront of climate mitigation discussions.[5] In this context, two popular options are as follows: one, technologies specifically designed to removal carbon from the atmosphere; and two, the age-old option of using trees to suck carbon out of the atmosphere.

The first option is also referred to as direct air capture and has been relatively new to the game. The second option is also referred to as forest offsets and has been part of carbon markets since the beginning, including the clean development mechanism. Both options, while attractive given the promise, have issues, however.

Direct air capture includes many options, almost all using chemical processes to suck carbon out of air and either burying it underground or using it as a feedstock in chemical processes. However, barriers to DAC are both practical and financial. At the end of the day, the cost would be up to $1000 per ton i.e., exorbitant, and too high compared to current and projected carbon prices.[6]

This brings forest offsets as a cost-effective carbon removal option.[7] Forests are abundant on earth, and it appears simple — just grow forests to suck carbon out of air. According to Pachama, a startup focused on measuring forest carbon, forests 1–3 times the area of the United States can be grown to create offsets.[8] Due to the promise, many stakeholders, including Mark Carney, ex-governor of Bank of England, are focused on using this option for achieving net-zero targets.[9]

Forest offsets have limited potential, plus greenwashing abounds

However, there are a couple of issues with focusing on forest offsets as the first line of attack in meeting net-zero targets. First, forest offsets are not likely to be a significant fraction of required carbon removal for getting to net-zero targets. For example, a recent meta study indicates that if we maximized the amount of vegetation earth could hold, we would sequester enough carbon to only offset about ten years of greenhouse gas emissions at current rates.[10]

Second, the focus on forest offsets has potential for significant gaming and greenwashing,[11] which simply results in actual performance not meeting promises.[12] In fact, up to 90% of carbon offsets have been found questionable in a recent study.[13] Here, the basic question is of additionality: How do we know that a forest offset project is above and beyond what would have happened anyways?

Sub-questions to the additionality question include the following. One, as NRDC points out, are old forests being cut and replaced by new forests to claim forest offsets, without any net increase in carbon sequestration capacity?[14] Two, as Bloomberg found in an investigation of Nature Conservancy projects, are forest owners claiming forest offsets for existing forests,[15] asserting that they would be cut down otherwise, and further increase carbon emissions if not preserved?[16]

The solution has been to calculate forest offsets based on a baseline, or a counterfactual[17] i.e., what would be the forest cover in the future in absence of the proposed intervention. While many frameworks are proposed to ensure additionality,[18] these baselines have proven very hard to establish, and they are open for gaming.[19] The basic issue is the complexity of statistical methods required to establish baselines. This suggests we need simple and robust methods.

Additionality of forest offsets needs to be established using simple and robust methods

Perhaps an easier way to ensure that the forest offsets are valid is as follows. One, count forest offsets on net growth in carbon carrying capacity of forests — i.e., the difference between afforestation and deforestation, while accounting for differences in carbon carrying capacities — from the beginning of a project, also known as time-zero. Given the focus on net growth, this would address the issue of old forests being cut while new forests are being planted.

Two, before starting a forest offset project on a land area, ensure that the forest density (or, even better, carbon carrying capacity) has not changed for a significant period (e.g., last 5 or 10 years) would take care of the issue of existing forests being cut down before the start of a project that then plants new forests and claims forest offset credits even though there is no net forest growth in the long-term.

Beyond these two simple strategies, a forest offset project would need to ensure that it is valid for a certain number of years (ideally, forever) after the beginning of the project (i.e., from time-zero), and an offset buyer is buying valid offsets for this whole duration. Thus, credible measurement and verification is a must, potentially using satellite imagery and artificial intelligence.[20][21]

Bottom-line, forest offsets can work in a limited fashion to get to net-zero. However, we need to have simple methodologies that work, without complicating measurement and verification. At the end of the day, we need to show net forest growth to enable additional carbon removal required to get to net-zero emissions.

[1] See What’s the target for solving climate change? | Environment | The Guardian

[2] See Net-zero by 2050: What does it mean? | Environment| All topics from climate change to conservation | DW | 31.05.2019

[3] See ETC_MissionPossible_ReportSummary_English.pdf (energy-transitions.org)

[4] See Making Mission Possible: Delivering a Net-Zero Economy (energy-transitions.org)

[5] See Explainer: 10 ways ‘negative emissions’ could slow climate change | Carbon Brief

[6] See Explainer: 10 ways ‘negative emissions’ could slow climate change | Carbon Brief

[7] See The Case for Forest Carbon Offsets | by Pachama | Medium

[8] See The Case for Forest Carbon Offsets | by Pachama | Medium

[9] See https://www.bloomberg.com/news/articles/2020-10-14/un-s-carney-says-carbon-offset-market-has-become-imperative

[10] See There aren’t enough trees in the world to offset society’s carbon emissions — and there never will be (phys.org)

[11] See Carbon offsets used by major airlines based on flawed system, warn experts | Carbon offsetting | The Guardian

[12] See An (Even More) Inconvenient Truth (propublica.org)

[13] See Not all carbon offsets are a scam — but many still are — Quartz (qz.com)

[14] See Planting Trees Isn’t a Climate Plan — It’s a Distraction | NRDC

[15] In fact, claiming carbon offsets on existing forests is not even carbon removal. It is termed avoidance, given that maintaining existing forests can help with the global carbon budget, especially if these forests would be cut down in the business as usual scenario.

[16] See A Top U.S. Seller of Carbon Offsets Starts Investigating Its Own Projects — Bloomberg

[17] See fcop_20_discussion_document.pdf (gov.bc.ca)

[18] See The Case for Forest Carbon Offsets | by Pachama | Medium

[19] See Should forest carbon credtis be included in CORSIA_0.pdf (climatefocus.com)

[20] See Not all carbon offsets are a scam — but many still are — Quartz (qz.com)

[21] See https://data.globalforestwatch.org/documents/14228e6347c44f5691572169e9e107ad/explore