Negative Emissions: “Only nature-based solutions can master the job”
An Interview with Professor Jelle Bijma about enhanced weathering
On my journey to do “something with enhanced weathering” I met Professor Dr. Jelle Bijma. Both of us are quite interested in the potential of enhanced weathering for CO₂ removal, especially applying the concept to farmland. For almost 30 years Jelle has been affiliated with the Alfred-Wegener-Institut, Helmholtz Zentrum für Polar- und Meeresforschung, Germany’s leading Institute for ocean and polar science. He is heading the section “marine biogeosciences”, where he studies the global carbon cycle and paleoclimatology.
A few days ago I had the chance to talk to him about the climate crisis and the enhanced weathering project that we are currently setting up together with several other people.
Dirk: Jelle thank you for taking the time for this interview! When we first met a few weeks ago you mentioned that it may be naive to think that we can stop (or reverse) climate change without creating collateral damage - but it would still be our better option. Can you explain what you meant by that?
Jelle: Over the past 150 years we have roughly put 1.500 gigatonnes of CO₂ into the atmosphere, along with other greenhouse gases. The atmospheric CO₂ concentration is now 50% higher than in 1850. These gases are not just warming our planet or acidifying our oceans, they also disrupt ecosystems that have evolved over millions of years by completely changing our climate. We live above the carrying capacity of the Earth and have reached a state where planetary boundaries are crossed or close to being tipped over. In my view it is not 5 to 12 but already past 12 and if we don’t succeed in stopping this process in the next few decades we will see more catastrophic floods, more draughts, more crop failures, more famine, more hurricanes and more bush fires such as this year in Siberia, Australia and California. We need to bring the CO₂ concentration down as soon as possible. Every second 1.145 (!) additional tons of CO₂ are emitted and need to be removed. Therefore, my major concern is related to our current inactivity and also the speed of removal that may be required if we trespass certain tipping points of the climate system.
Dirk: What are the dangers?
Jelle: The crew of an oil-tanker has to slow down their speed long before the harbor comes into sight. If they miss the point of “no return”, the catastrophe cannot be avoided anymore. We may be close to planetary tipping points and the stakes are simply too high that we can take that risk and therefore need to act now. The magnitude and rate of our greenhouse gas emissions will cause irreversible/catastrophic damage which will likely be much greater than the collateral damage the various mitigation methods might create. It is quite possible that we won’t be able to fix the primary problem without creating new but smaller problems, but if we can avoid the worst climate change consequences then it is worth paying that price.
Dirk: What is your strategy to solve this?
Jelle: We live in a world where engineers create technical masterpieces and we are technically so advanced that everything seems possible. Some people believe that someday we have a magic technical solution for our CO₂ problem, a “silver bullet”. Others propose Solar Radiation Management (SRM), which for me is too ridiculous to even discuss here as ocean acidification would simply continue. For other scenarios such as carbon capture and storage (CCS) we need to solve the tricky CO₂ storage problem at a gigantic scale. In my view, only nature-based solutions can master the job as they pose the least risk but not all are equally effective. For instance, Bio-Energy with Carbon Capture and Storage (BECCS) is competing for space with food production and afforestation and may not be very sustainable. Without going into a critical evaluation of these methods here, my favorite is enhanced weathering on farm land, and for good reasons.
Dirk: You have been working on ocean science for most of your professional life, why are you looking at enhanced weathering on farmland and in soils now?
Jelle: It is quite understandable that a country wants to regulate the use and misuse of its territorial and economic zone. The German government has not just ratified the “London Convention on the Prevention of Marine Pollution”, it went even further and adopted a law that specifically forbids the addition of alkalinity to the ocean. This basically excludes ocean alkalinization as a way of restoring oceans’ health. Changing the law will take years that we do not have. It is as simple as that.
Dirk: So now we are trying to come up with a pilot project for enhanced weathering on land together. Can you explain the idea?
Jelle: The idea is to spread powdered rock such as basalt or olivine on farmland while we continue to use it to grow crops. When these materials dissolve, the products will react with the CO₂ from the air and store it literally forever. All you have to do is grind the stone and spread it on the ground, it is a “low-tech” solution. All you need is mining and farming equipment that has already been developed. Nature does the rest because this process is Earth’s natural process to draw down CO₂. We are just speeding it up a little bit by grinding the rocks and placing them in a favorable setting.
To me this seems to be the best solution as agricultural land surface is readily available just as the farming infrastructure is and it does not compete with food production. On the contrary, it can enhance crop yield. If the carbon credits reach a realistic value this will become an additional business model for farmers’ income (carbon credits + rock flower would replace liming and a large fraction of artificial fertilizers). The additional annual revenue from enhanced weathering could be as high as several hundreds euro per hektar, we believe it may be in the range of 10-20% more revenue per hektar, maybe even more. To improve soil quality and nutrient retention it can be combined with biochar, which enhances carbon drawdown even more. Above all, it seems a rather safe method from which, at the end, everybody profits.
Dirk: But isn’t the “job” too big even for enhanced weathering solutions?
Jelle: Agreed, 1.500 gigatonnes of CO₂ is an astronomical number and even the order of magnitude of ca. 40 Gt that humans emit annually is difficult to grasp. But doing this job is quite possible. For comparison, we are mining and transporting 6-8 Gt of coal every year. About 50 (!) Gt of sand and gravel are moved every year, so logistically it can be done. One ton of basalt or olivine could permanently store about 0.5 to 1 ton of CO₂, respectively, depending on the share of renewable energy used. If our goal is to sequester about half of our current emissions annually, we are talking about 40 to 80% of the current annual global sand and gravel business. That seems quite feasible. I’m not saying that enhanced weathering (EW) is the Holy Grail for negative emission scenarios. We will need a whole portfolio of methods but above all we need emission reductions and transition to renewable energy sources as soon as possible.
Dirk: But the problem is, that we don’t have reliable data on how much CO₂ is actually captured and stored….
Jelle: Yes. There are hundreds of scientific papers about enhanced weathering which have mostly shown that the concept actually works. But we do not know how fast and how much of the CO₂ capturing potential of the basalt/olivine is actually used in a year or two.
Dirk: The EU and IPCC expect to capture 10 Gt per year in 2030, in just ten years. That’s gigantic. With that in mind I am still amazed (and also desperate) that crucial information like “how fast and how good does enhanced weathering work” is not even close to being understood even after 20 years of science work on enhanced weathering…
Jelle: Don't be desperate, this can easily be explained. Initially, silicate rock weathering wasn't even given a thought as a solution for mitigating climate change as it had always been associated with extremely slow processes on geological timescales and extrapolation of abiotic experiments suggested that weathering is not fast enough. Only when people like Professor Olaf Schuiling from Utrecht University realised that crushed serpentinite mine tailings weather much faster than basaltic tuffs in even the most favorable climate for weathering and that outside the laboratory the role of biotic factors like mycorrhizal fungi on land or lugworms on tidal flats could speed up the weathering reaction by factors of ten to almost one thousand, he and Poppe de Boer started their uphill battle. So it is only in the last 10 years that mainly Dutch “disciples”, inspired by personally meeting Olaf, started to seriously look into enhanced weathering for CO₂ removal.
Dirk: So what slowed their work down?
Jelle: They mostly did this work on the side as funding was scarce, the term “geoengineering” is not very popular and also has the very bitter taste of nickel. It is therefore not a coincidence that The Netherlands became a hotspot for “enhanced weathering” thinking. Initially, the focus was on using olivine for various cost-effective applications and sustainable sequestration of CO₂ without a specific focus on the speed of the carbon drawdown. For that, the theoretical calculations of the weathering rates were sufficient.
It was only when the public pressure to mitigate the impacts of climate change became too loud to be overheard by the political establishment and when it also became clear that international climate agreement goals could only be reached by the application of negative emissions, that a full proof carbon accounting for enhanced weathering was required (to match carbon credits).
However, funding programs designed by national governments are so slow that we haven’t even started in Germany yet. It is really the drive of NGOs and the vision and support of philanthropic foundations such as yours and Ralph Koczwara’s company Fieldcode that is moving us forward. A big thank you!!
Dirk: Ralph Koczwara and I realized that the speed of development with the usual scientific process of applying for funding, waiting for funding etc. is way too slow to match the urgency of the problem. So we decided that we will engage ourselves into this to gain the necessary speed.
For my last question let’s go back to the ocean where you spent your last 30 years. As you know I am also supporting Project Vesta. They also work with olivine, but they intend to spread on beaches, not farmland. What advantages do you see for each method and which one do you expect to become the “bigger thing”?
Jelle: The grains of olivine on a beach are constantly kicked around by the waves, their surface is constantly broken up - which speeds up the chemical reactions and there is lots of water. On land, the biology of the first 50 cm of the soil is very active, this also acts as a reaction enhancement. It is too early to call a winner and we probably need both.
In the end any successful enhanced weathering project will need to answer three questions:
Is it quick enough and will it scale enough to actually mitigate climate change before 2050?
Does it at least pay for itself, even better, can the person doing it earn money with it (if necessary with a carbon tax)?
Does it release unbearable amounts of toxins or other waste?
With our pilot project we want to be able to address all three questions for enhanced weathering on land by the end of 2021. We have a lot to do until then.
Dirk: Thank you, Jelle!