Anil Madhavapeddy

The Cambridge "Green Blue" competition to reduce emissions / May 2025

Carl Edward Rasmussen recently gave a great talk in our group about his thoughts on mechanisms against climate change. He persuasively argued that the Paris Agreement was doing more harm than good by giving the illusion of being a concrete agreement, but is in reality a huge distraction. Our actual emissions have increased since the Paris agreement was signed!

Carl argues that a climate system ultimately only responds to collective actions, and without a global cooperative incentive each nation will spring back to their own isolated short-term incentives that lead to an increase in fossil fuel burning. He has just published the "Themis Mechanism" as a simple alternative for equitable global emission reduction (long form). (6th May 2025: See a new article on Themis as well)

This got me brainstorming with Carl about how to test his theories out and we came up with an idea that is either terrible or awesome; please read on and judge appropriately. I think we should take advantage of Cambridge's unique structure to trial the Themis mechanism via a new competitive decarbonisation sporting league among Colleges that I dub the "Cambridge Green Blue". Given the Chancellor's recent unveiling of an innovation corridor between Oxford and Cambridge, the timing could not be better for an initiative like this. (TL;DR sign up at the bottom of this post if you'd like to participate)

Read full note... (4038 words)

Disentangling carbon credits and offsets with contributions / Feb 2025

The terms carbon credits and carbon offsets are often used interchangeably, but are in fact two distinct concepts. I've spent a nice Sunday morning reading up on some recent articles that Bhaskar Vira sent me which introduce a third term, known as "carbon contributions". Rather than this adding confusion, I found it helped me clarify my own thoughts on the matter, which I note down here in draft form. (Update 7th Feb: I've revised this several times after many discussions this week, especially with David Coomes and Srinivasan Keshav, with full list of credits in the end)

Read full note... (3552 words)

Position paper on scientifically credible carbon credits (via 4C) / Jan 2025

My colleagues Thomas Swinfield and Eleanor Toye Scott lead the publication of a comprehensive report of the steps the voluntary carbon market needs to take to restore its scientific credibility, with input from many of us in 4C and beyond.

• establishing common standards for carbon quantification and accounting, to cover additionality, leakage and permanence.
• avoiding perverse incentives and align the motivations of all stakeholders with high-integrity outcomes. [...]
• issuing all carbon credits based on trusted primary observations.
• making all the data needed to reproduce carbon calculations available in standard file formats.
• [...] reporting social and biodiversity dimensions of projects separately from carbon calculations.
• integrating DMRV methods into carbon and biodiversity accounting standards to reduce the financial and administrative burdens on nature-based projects and the local communities participating in or affected by them.

Read full note... (186 words)

LIFE metric published in Royal Society Phil Trans B / Jan 2025

After some years of hard work, our Mapping LIFE on Earth biodiversity metric was published today in a special issue of the Royal Society Philosophical Transactions B! The idea behind LIFE is that although human-driven habitat loss is known to be the greatest cause of the biodiversity crisis, we do not yet have robust spatially explicit metrics that quantify the relative impacts of human actions on species extinctions. And that's what LIFE provides: a way to compare the relative impacts of some landuse anywhere in the world, in a manner that is globally applicable.

Read full note... (409 words)

Royal Society meeting on ecological/commercial risks / Oct 2024

I'm at the Royal Society this morning for the 2 day programme on "How does ecological risk related to commercial risk?", and am reporting on the morning session. The full program is being livestreamed so please do dial in if the below notes seem interesting to you. I put this note up almost live, so any errors below are my own. (Update: partial day 2 notes now available below)

Read full note... (6736 words)

Mitigating credit reversal risks in nature-based solutions / Sep 2024

Many of the questions around our recent Nature Sustainability commentary on NbS credits revolve around how to finance new projects if credible credits need to be ex-post. Our latest paper published in Carbon Management on "Mitigating risk of credit reversal in nature-based climate solutions by optimally anticipating carbon release" tries to address this.

The problem with selling ex-ante (future) carbon credits for (e.g.) a deforestation avoidance scheme is that project reversals can happen in the future ("deforestation has increased") thus rendering any credits issued previously useless. On the flip side though, an overly conservative view of the future ("the entire forest will disappear overnight!") is clearly so conservative that it doesn't serve the best interests of the project developer. So ideally, a project would make realistic but conservative ex-ante predictions that is safe for both project developer (who gets more funds upfront) and a carbon credit purchasers (who needs to account for impermanence of nature credits).

Our paper shows how to do this by calculating a "release schedule" to predict future drawdowns, and then issuing extra credits when the release at some future date is less than predicted by the release schedule. We use verified ex-post observations to construct these release schedules, and design them to bound the risk of the project becoming negative overall (that is, net drawdown is negative) and thus failing.

Read full note... (355 words)

Paper published on ex-ante forecasts of nature-based solutions / Aug 2024

Our paper on ex-ante projection for nature-based solutions has been published in the Journal of Carbon Management. I also wrote up some long-form thoughts on it here. The publication represents the culmination of work on how to properly account for credit reversal risk in nature-based climate solutions through optimal carbon release anticipation. E-Ping did excellent work leading the methodology development and analysis. The approach we developed incentivizes project performance while resolving the fundamental trade-off between a credit's permanence rating and risk reduction, providing a pragmatic solution to one of the key challenges facing the effectiveness of nature-based climate solutions.

Nature Sustainability commentary on carbon and biodiversity credits / Aug 2024

Our commentary on nature-based credits has been published in Nature Sustainability, lead expertly by my colleagues Thomas Swinfield and Sophus zu Ermgassen.

In our view the carbon credits markets are vitally important for forest conservation, but the key is to only transact these credits after they have been proven to be demonstrably additional using robust statistical techniques, so that we know before a sale that each credit represents real gains that would not otherwise have occurred without the carbon finance.

A more scientific approach that supports transparent, third-party validation could absolutely transform these markets. And given the rapid rate of tropical forest loss, such upscaling of credibility is vitally necessary to raise investor confidence in protecting nature, since we can now be confident that every "credit" sold is resulting in real climate benefit. There are real questions remaining about this reform, of course.

Read full note... (509 words)

Nature Sustainability article on carbon/biodiversity credits / Aug 2024

Our commentary on nature-based credits has been published in Nature Sustainability. I wrote some thoughts about it here as well. This piece argues that nature-based credit markets are at a critical crossroads - recent impact evaluations showing disappointing results have threatened investor confidence. We make the case that these markets need fundamental reform to adopt the latest scientific understanding on additionality, leakage, and permanence. The key proposal is releasing credits ex-post only after proven demonstrable additionality relative to statistically-derived counterfactuals, and making credit estimation methods robust to rather than resistant to scientific improvements. Without these reforms, we risk losing one of our most promising tools for drawing private investment into conservation.

Second preprint of the LIFE biodiversity metric available / Jul 2024

We have made an update to the LIFE biodiversity metric based on reviewer feedback, and are very pleased that it has been accepted for publication early next year as part of a special issue from the Royal Society. Any comments would be most welcome before we submit the final proofs in a few months. The revisions incorporated feedback from peer reviewers and represent an improved version of the methodology. Getting accepted for the Royal Society special issue is particularly exciting as it means the LIFE metric will be published alongside other important contributions to biodiversity science. This metric has already proven useful in our work on food systems and will hopefully become a widely-used tool for quantifying biodiversity impacts across diverse applications.

Global, robust and comparable digital carbon assets / Apr 2024

Paper on smart contracts for carbon credits at ICBC 2024 in Dublin. This work proposes the PACT stablecoin, which addresses concerns about credibility, scalability, and liquidity in voluntary carbon markets. We combine remote sensing data, modern econometric techniques, and blockchain-based certification and trading to create digital carbon assets against which offsetting claims can be transparently verified. The key innovation is creating a reproducible computational pipeline that not only quantifies CO2 emissions but also allows credits to be pooled based on co-benefits like biodiversity and jurisdictional attributes, increasing liquidity through fungibility. We implemented it on the Tezos blockchain, which is designed for low-cost transactions with minimal environmental impact.

Preprint available on insuring against variability of NbS / Mar 2024

A new preprint is available on our work on ex-ante pricing models for nature-based solutions. It is currently under review, so any feedback is most welcome! This paper tackles the challenge of variability in the performance of nature-based climate solutions by developing optimal release schedules that balance generating credits with higher permanence ratings against limiting the risk of negative additionality. We use Monte Carlo simulations on both theoretical and real-life projects to show how conservatively anticipating carbon release and issuing additional credits when reality is less pessimistic than projections can provide pragmatic insurance against the inherent uncertainty in these systems.

Nature Climate Change paper on impermanent carbon credits / Nov 2023

Our paper on valuing impermanent carbon credits has been published at Nature Climate Change. It has received a bunch of press coverage, including phys.org, cam.ac.uk, and Mirage. The publication follows our July preprint and represents a significant milestone in bringing scientific rigor to carbon credit markets. The press coverage has been really encouraging, with science journalists picking up on the key insight that our framework allows for like-for-like comparisons of diverse carbon projects while generating incentives for safeguarding already-credited carbon. The methodology we developed integrates three substantial advances that together provide a path forward for credible nature-based climate solutions.

First preprint of LIFE biodiversity metric available / Nov 2023

The first preprint on our new LIFE metric for global biodiversity is now available. It is under review, so feedback would be very welcome. LIFE stands for Land-cover change Impacts on Future Extinctions and represents a significant computational achievement - we generated global maps at 1 arc-minute resolution covering 29,153 terrestrial vertebrate species. The metric quantifies the marginal changes in expected extinctions from either converting natural vegetation to agriculture or restoring farmland to natural habitat. By coupling the persistence score approach with high-performance computing, we've created a tool that integrates information on species richness, endemism, and past habitat loss, offering unprecedented opportunities to estimate extinction impacts from scales ranging from individual dietary choices to global protected area development.

Preprint on the social value of impermanent carbon credits / Jul 2023

We have uploaded a preprint of our 4C paper on valuing impermanent carbon credits, by using the Social Cost of Carbon as a basis for a discount function into the future. Comments and feedback are most welcome. This work tackles one of the biggest challenges in nature-based climate solutions: how to value carbon sequestration that might not be permanent. We developed a novel framework that conceptualizes permanence as additionality over time relative to a counterfactual baseline, uses risk-averse estimation of future carbon release, and deploys post-credit monitoring to correct for overly pessimistic forecasts. Our preliminary comparisons suggest that even after fully adjusting for impermanence, nature-based interventions may offer less costly ways of reducing climate damages than more technological solutions.

Credit credibility threatens forests / May 2023

Our perspective in Science magazine appeared this week on the credibility of carbon credits and its importance for tropical forest protection. This was a collaborative effort with colleagues from across conservation science, economics, and computer science to address one of the most pressing issues in climate finance. We argue that improving the quantification methods behind carbon credits is not just a technical issue but an existential one for forest protection. If credits don't accurately represent their environmental benefits, the entire voluntary carbon market risks collapse, which would be catastrophic for tropical forests that depend on this financing. The piece calls for robust, scientifically-grounded methodologies to ensure that carbon credits can genuinely contribute to climate mitigation rather than providing false assurance.

Addressing global warming requires increased investment in conserving and restoring carbon-dense natural habitats. Some companies that emit carbon have turned to certified carbon credits to offset their environmental impact. However, the effectiveness of carbon credits depends on the methods used to quantify them. If carbon credits do not accurately represent their environmental benefits, relying on them could exacerbate climate change. To ensure that carbon credits are robust, the methods used to calculate them must be improved.