International Conference on Negative CO₂ Emissions 2024
ADD-TREE and NetZeroPlus researcher, Dr Anna Harper, recently attended the International Conference on Negative Emissions 2024, hosted in Oxford. Negative emissions (or removals of CO2) are essential for limiting climate change, and they already play a role in many countries’ pledges for meeting the Paris climate agreement. In this conference, we mostly talked about Carbon Dioxide Removal (CDR), ignoring other greenhouse gases like methane and nitrous oxide. Here are some of the highlights and key take-aways from the conference Anna’s perspective.
Global and national perspectives on CDR
The meeting started with a talk from Steve Smith, a lead author for the State of CDR Report (2nd edition). According to this report, across a suite of scenarios that met minimum criteria for sustainability, around 7 to 9 billion tons of CO2 per year could be removed from the atmosphere by 2050. These scenarios tend to have rapid emissions cuts, which limits the overall amount of CDR needed, and they tend to rely on more conventional CDR methods compared to novel methods that have not yet been scaled up. For context, global emissions are now close to 40 billion tons of CO2 per year.
The figure below is taken from the 2nd State of CDR Report.
Where are we now, in terms of actually deployed methods of CDR? So-called conventional methods (forest-based methods, peatland and wetland restoration, soil carbon management in agricultural systems, and storage in durable wood products) already remove around 2 billion tons per year. Biochar dominates the non-forest CDR scene, especially in the U.S. where there are many small-scale projects. The next biggest non-forest method is bioenergy production with carbon capture and storage (BECCS), although there are currently only two places where this is done (Illinois Industrial Carbon Capture and Storage facility and the Red Trail Energy bioethanol initiative, both in the U.S.). And last, although very small, is enhanced rock weathering (ERW).
Individual countries are also assessing how they can contribute to net zero emissions. Wenqin Li, from Lawrence Livermore National Lab, gave a talk on Wednesday about the U.S. Department of Energy (DOE) Roads to Removal report. This looks at how CDR can help the U.S. can achieve net zero by 2050. They did a lot of detailed modeling to evaluate consequences of several scenarios. They found that the U.S. can remove 0.5 to 1.5 billion tons of CO2 per year by 2100. This would primarily come from forestry, agriculture, municipal solid waste, and bioenergy crops, but which method makes the most sense varies a lot by region. I definitely plan on digging more into this report!
Finally, on Wednesday afternoon there was a fascinating panel on CDR in national policymaking. The panelists were Gideon Henderson (UK), Fabiola Zerbini (Brazil), Jen Wilcox (US), and Fabien Ramos (EU). They have each played a role in national/EU-scale climate policy over the past few years. It was enlightening to hear about the challenges (like the slow pace of setting environmental policies and short political cycles) and opportunities (such as the newly funded direct air capture hubs in the U.S.). Dr. Zerbini’s perspective was fascinating, she is the Director of the Brazil Department of Forests and focuses on restoring and protecting ecosystems across Brazil (not just the Amazon!). I had the good fortune of sitting across from her at dinner that evening and was impressed with her fortitude to push for positive policies in Brazil.
Forests
In the Forest session on Tuesday, I gave a talk on a task that has occupied much of my time over the past 3 years – making a global vegetation model suitable for predicting carbon cycle impacts of tree planting at a country level. This has involved better representing forest dynamics, management, and model calibration. The work has been funded by the NetZeroPlus project, and more lately by ADD-TREES (AI-elevated Decision-support via Digital Twins for Restoring and Enhancing Ecosystem Services). Hsi-Kai Chou, who also worked on NetZeroPlus, was presenting in the same session, so we were able to go into some detail on the motivation and developments (my talk) and results (his talk). I’m working on a paper from the talk along with the rest of the JULES / NetZeroPlus team, stay tuned.
Earth system modelling
A session on Earth System Models was another highlight of the conference for me. This featured talks from Julia Pongratz (CDR potential from both Afforestation/reforestation and ocean alkalinity enhancement), Ruben Prutz (CDR implications for global biodiversity refugia), and Ian Bateman (PI of the NetZeroPlus project). These were great talks each focusing on different aspects of the Earth system (climate, biodiversity, and coupled human/economic/land systems). All of these perspectives are necessary as we face decisions about CDR and how to achieve net zero. As an Earth system modeler, I enjoyed Julia’s talk investigating whether the two CDR methods could be deployed together without compromising the efficiency of each. In general, using the MPI climate model, they found that the removals from the two methods are additive, although at very high levels of CDR there was a saturation of how much CO2 the oceans and forests could absorb.
Networking & enjoying Oxford
We also had a gourmet vegetarian dinner on Wednesday evening at the beautiful Keble College. Personally, I find that big dinners after a full day of conferencing can be very draining. But I’m always glad I put forth the effort, and I have found ways to manage my energy levels by building in personal time at other points during the conference. The food was delicious, the setting was beautiful, and I had an enjoyable evening talking about more than just CDR with many new and old colleagues.
