Takeaways so far from the CDR Primer

As of now I've read the first 3 chapters: here are some highlights and questions that come to mind.

Hi all,

Unless you’ve been living under a rock you’ve probably seen the awesome CDR Primer released last Thursday! I’ve been going through it pretty carefully and learning a lot, from CDR science processes to arguments that are changing the way I view the CDR space. I’m deeply appreciative of all the authors who worked to put it together.

If you’re looking for some motivation to get started reading it, I’m hosting a book club discussion with Air Miners over the next 5 weeks to discuss each of the CDR Primer’s 5 sections! First meeting is this Friday, January 22nd at 3pm ET, so sign up at this link, come having read Chapter 1 of the Primer (along with the Foreword and Preface!) and with plenty of thoughts and questions to discuss!

Highlights and Thoughts on Chapters 1-3 of the CDR Primer

One bigger picture thought before I get started: what an epic set of references this Primer has racked up! It may be freeze-framed at this moment in time, but it’s pretty awesome to have this treasure trove of all of the most important CDR papers and reports, many of which were new to me. Plenty of rabbit holes to go down!

Foreword and Preface

As you start reading the CDR Primer, do yourself a favor and don’t skip the Foreword and the Preface! From the Foreword by Holly Jean Buck and Roger Deane Aines:

Carbon dioxide removal at a climate-significant scale is one of the most complex endeavors we can imagine, interlocking technologies, social systems, economies, transportation systems, agricultural systems, and, of course, the political economy required to fund it.

I feel like I need to print this out and stick it on my wall - I really wish more people understood what a compelling, multi-disciplinary, and important problem carbon removal is, spanning and interacting with essentially every industry and discipline. I could not be more excited to be working on it.

The Preface, written by students Justine Davids and Katherine Vaz Gomes, is super inspiring and speaks to me personally as an undergrad looking at the CDR space.

This primer opened us up to a world of possibilities, where creative young minds are allowed to run with big ideas that could save the planet. As newcomers to this space, we were inspired by the collective knowledge this primer shares: generations of experts blending many different areas of expertise into a symphony of carbon dioxide removal strategies we can use in the fight to stop climate change. 

Well damn. I wanna be a creative young mind running with big ideas to save the planet. Time to open up the book proper!

Chapter 1

This chapter, written by Andrew Bergman and Anatoly Rinberg, sets the tone for the book by laying out what the role of carbon removal is in the bigger picture fight against climate change, describes the critical ways in which CDR interacts with the broader carbon cycle, and frames everything within the perspective of social and environmental justice.

Some thoughts on specific topics brought up:

One thing is clear: scaling up carbon removal is really, really hard.

While many Integrated Assessment Models conclude that we’ll need a massive tens of gigatons per year of CDR just to reach net-zero by weighing climate strategies on the basis of cost alone, the authors of Chapter 1 instead take a bottom up approach and ask what the bare minimum of carbon removal needed would be to only offset emissions that are too hard to abate, either from physical limitations (i.e. air travel) or social justice concerns (i.e. some agricultural emissions). This number comes out to be somewhere between 1.5-3.1 GtCO2/yr, a still large but not nearly as crazy scale.

This analysis and new way of thinking about CDR scale-up is really interesting, but leaves me with the question: what happens after we achieve net-zero, and if we decarbonize aggressively enough stabilize at 1.5 or 2C? The 1.5-3.1 GtCO2/yr CDR would be enough just to reach a steady state of net-zero emissions, but this seems to leave out using carbon removal to deal with legacy emissions and come down the other side and bring atmospheric CO2 concentrations back to 350 ppm. A world warmed to 2C isn’t a great place to be, so additional carbon removal seems like it’s inevitably on the menu.

In the section on the carbon cycle, I finally saw a clear articulation of a kind of chilling fact that I feel like not enough people in the carbon removal community appreciate:

First, just as land and ocean sinks take up a portion of the carbon that humans emit, removing CO2 from the atmosphere initiates its own feedback processes (Figure 1.2c-d; Keller et al., 2018). Following large-scale CDR that reduces atmospheric concentrations of CO2, some amount of CO2 will return to the atmosphere from the ocean and terrestrial biosphere, dampening the efficiency of CDR (Jones et al., 2016; Tokarsa et al., 2015). For example, one modelling study examining the Earth’s climate system in a pre-industrial steady state found that instantly removing 367 GtCO2 from the atmosphere would reduce atmospheric CO2 concentrations by only 92 GtCO2 (or about 25 percent of the initial magnitude) after 100 years (Figure 4 in Keller et al., 2017). 

The fact that there are carbon cycle equilibrium processes reducing the effectiveness of our efforts to remove CO2 from the atmosphere makes things a lot more complicated in my mind. When a company pays to offset 1 million tons of CO2 emissions via carbon removal, the amount of CO2 in the atmosphere doesn’t actually decrease by 1 million tons. If that 25% of initial magnitude number applies across all CDR efforts (probably a bad assumption), then the workload to clean up legacy emissions seems to have increased by a factor of four.

Finally, this chapter explores the all-important social justice questions that surround the process of CDR scale-up. Should oil/gas industry have any role in a climate justice-oriented approach for CDR scale-up? How do we avoid harms in the first place, not reverse damage? Should carbon removal infrastructure be publicly owned? How do we engage and help frontline communities throughout the process of carbon removal scale-up?

Really appreciated this EJ framing of the Primer, and just wish that these questions were further baked into the rest of the book, which shifted mostly to CDR science and logistics.

Chapter 2

Here’s my recommendation: Chapter 2.1 (on carbon mineralization) and to a lesser extent Chapter 2.2 (on ocean alkalinity enhancement) are really hard to read if you aren’t comfortable with academic science writing (lots of chemistry here). I’m really glad I powered through it because it’s very good and I learned a lot, but don’t be discouraged if you have to skip to Chapter 2.3 and come back to Chapters 2.1 and 2.2 later. The chapter definitely becomes much more readable to a lay audience after the beginning.

As advertised, if you want a thorough review of the basics of carbon removal science, it’s hard to do better than this. It was cool to see a lot of scattered facts that I had picked up from random conversations or papers be laid out systematically here.

Some thoughts I had while reading:

I actually laughed out loud when after a full section on ocean alkalinity enhancement (OAE), describing how we can add minerals to the ocean to achieve enhanced weathering, the authors hit us with:

While it is currently not permitted to add materials to the ocean (IMO, 2008, 2003), large parts of the supply chain (mineral extraction, transport, calcination) to do so already operate at global scale.

Adding materials to the ocean seems to be a key step here, haha. I wish the section had expanded a bit more on the treaties preventing this and how they might be reckoned with for the purposes of OAE.

In the section on Forest CDR, I was struck by the initial framing of the section with the sentence:

We emphasize that preventing emissions by slowing or stopping deforestation (often referred to as “avoided conversion”) is another crucial climate change mitigation strategy, has generally much larger per-unit-of-land-area climate benefits than forest-based CDR approaches, and will have a much more rapid positive climate impact than forest-based CDR approaches.

I really like that the Primer is very conscious of the limits of CDR, how it interacts with different non-CDR mitigation strategies, and still does a very thorough job going into the literature and quantifying where the potential is.

For me, the highlight of this chapter was the last three sections, on BECCS, DAC, and Geologic Sequestration. Really good explanations that articulate complex processes clearly. Go read!

Chapter 3

This chapter is really cool. With lots of fun color-coded world maps, it asks some important CDR implementation questions like what energy sources we can use and where we might site some of these processes. The exploration of energy resources is fascinating: it touches on the synergies between different low-carbon energy technologies like concentrated solar power, geothermal, and nuclear with DAC and other CDR approaches, and discusses where geographically we might best harness these synergies. I’ve been thinking about doing more research on geothermal + carbon removal, and really appreciated the discussion of how geothermal plants actually work, how oftentimes they aren’t even carbon-free energy, and where in their power production process DAC can fit in.

The chapter gets into the weeds a little bit when talking about the various mappings of geologic sequestration capacity (I was skimming a bit during that part), but it’s still helpful to understand what different criteria are used by different studies to assess whether a sedimentary basin could be a potential sequestration site.

Another highlight for me was the section on the different alkaline wastes that can react with CO2 in mineralization or enhanced weathering reactions for CDR. I was definitely unclear on what fly ash, cement kiln dust, slag, and red mud all actually are, but the chapter did a good job explaining which industrial processes each one comes from and how they stack up in terms of sequestration potential.

Also, serpentinite is the most badass name for a mineral. 10/10.

Glad you made it this far! I’ll briefly cover the last 2 chapters in next week’s newsletter. Again, go check out the CDR Primer. Then, reply to this email and let me know your thoughts or questions!

Carbon Removal Meme of the Week

If you have any carbon removal memes (or are inspired and decide to make one!), please send them to me! I’ll highlight my favorite CDR meme each week here.