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CDReality: Should we focus first on Decarbonization, and wait to do CDR later?

Decarbonization, or preventing future emissions through conversion to zero carbon alternatives, is critically important. But we will need CDR as well, so we need to develop it now. You will hear the “more bang for the buck” argument from staunch CDR opponents as well as from thoughtful people who wonder how best to spend the limited resources we have.

The bottom line

The answer to this claim comes down to this simple message: we need both rapid decarbonization and CO2 removal. Either one alone will not be enough to keep global warming below 1.5 C. Currently, most CDR solutions are still in fairly early stages of development or deployment and need support to mature and scale up.

We need CDR. It won’t just happen, so we need to invest.

The IPPC AR6 states that CDR at multi-gigaton scale will be a required part of any pathway to maintain 2 degrees or less of global warming.

This is for two reasons:

  • We have already emitted gigatons of CO2 since the beginning of the industrial revolution. The overwhelming majority of this legacy CO2 is still in the atmosphere and will likely remain there for hundreds of years–unless we remove it.
  • while we need to decarbonize as quickly as we can, hard-to-abate emissions (from aviation, cargo transport, steel production, agriculture, etc.) will be with us for decades. Decarbonizing these sectors will be very difficult, expensive, and time-consuming. Doing it too quickly will harm poor and disadvantaged people the most.

This makes it clear what we need to do: add as little as possible new CO2 (decarbonization) and remove as much as we can (CDR). Neither one alone is sufficient.

The milk jug analogy

If you knock over an open milk jug on your kitchen counter, you do two things: you grab it and stand it up again so no more milk spills; and you reach for a towel and start mopping up the milk that is spreading on the counter.

The milk, of course, is the CO2, and while somewhat simplistic, the analogy gets the point across that either action alone is not enough.

Just as we need a towel to mop up the milk in our analogy, we need CDR to remove CO2, and we’d better get really good at it really fast. This will only be possible if we invest in different CDR solutions (really absorbent towels and sponges) now. We can’t wait for all the milk to be spilled and then start thinking about ways to remove it.

Two more things

Opponents of CDR like to reduce the renewables vs. CDR issue to a zero-sum game where every dollar CDR gets comes out of the mouth of renewable energy, so to speak, starving it.

That absolutely does not have to be so. An example is the OpenAir-drafted CDRLA bill in New York, which proposes to fund CDR procurement by eliminating existing tax credits for commercial aviation fuel. No money gets diverted from programs that support the transition to renewable energy.

There is another curious inconsistency in this argument: renewable energy has been massively funded and supported by governments in many countries (unfortunately about three decades too late, but that’s a different story). This led to a thriving industry, where the markets are now taking over and governments’ role will eventually wane. Renewables are themselves a perfect example of how government funding and support can create an entire industry.

CDR is at the same fledgling stage renewables were a decade or two ago. The same approach can work. Investment, e.g. by the US government into CDR, esp. DAC hubs as well as increasing VC funding (e.g. the $650M round Climeworks secured in 2022) an encouraging sign that more funding

(Note: this graph was made before Climeworks raised a large round and Alphabet, Meta, Shopify and McKinsey launch the almost $1B Frontier Fund. The yellow sliver of a line will be ever so slightly wider now.)

Let’s turn this argument around

Sometimes a good offense is the best defense, so let’s turn this argument around. Emission reductions have been called for since the early ’90s. The result has been emission increases year after year (with the exception of 2020, but that was due to COVID, not actual progress). While we all agree (profoundly!) that ending fossil fuel emissions is critical, humanity’s track record is admittedly pretty bad.

This raises the question of why the “decarbonize-only” crowd has any level of confidence that dramatic emission reductions are achievable in the short term. We’d all like it to be so, and we will all push for it to happen as much as possible, but to pretend that the odds are good feels like wishful thinking.

The use of renewable energy is growing. The main reason for that is economic. Renewables are now cheaper than coal and many other fossil fuels and particularly nuclear energy which has a lot of vocal proponents among conservatives. Therefore, market forces are driving consumers towards those cheaper options.

We need to create the exact same thing for CDR.


Scale-up has to start now

We might repeat ourselves here, but we’ll say it one more time so it really sinks in: There is no effective CDR without decarbonization. Any CO2 molecule we do not emit, we do not need to remove.

While cities, states, countries, companies, and industries work on (or delay) decarbonization, we continue to emit CO2 on the gigaton scale and will continue for some time to come. Some sectors are harder than others to wean off of fossil fuels and–realistically–some level of CO2 emissions will be with us for a while.

Here is another point that bears repeating: we know we will need CDR at a massive scale by mid-century so we can begin the work of undoing the damage we have done. Most (probably all) CDR approaches are not yet mature enough to be deployed at the massive scale that’s needed, and to get them there in the coming decades, we need to invest now. We need to develop them so they can someday be deployed widely at a fraction of today’s cost.

We know it can be done–we’ve seen it happen with solar energy–and we know what it takes: money and time. Every dollar we invest today will reduce the overall cost and shorten the timeline to achieve the capacity we need.

Solar – a perfect example

Solar panels were few and far between even ten years ago. They were expensive and people were reluctant to deploy them. This has changed dramatically: “the cost of solar/photovoltaic has come down by 82% between 2010 and 2019” [link].

Assuming a similar rate of cost reduction, even the most expensive CDR approach to date, direct air capture, would cost $90 per ton of removal within ten years. $100 per ton is considered the threshold for CDR to be economically feasible.

Decarbonization – easier said than done

Opponents of CDR claim that “all” we have to do is to decarbonize our entire economy. However, decades of experience have proven that this is far from trivial. In fact, decades of experience show failed emission reduction targets and broken promises rather than the progress we need.

The pace of decarbonization that is required to meet the Paris temperature targets vastly exceeds anything in the historical record at the global scale.

Moore, F.C., Lacasse, K., Mach, K.J. et al. Determinants of emissions pathways in the coupled climate–social system. Nature 603, 103–111 (2022). Determinants of emissions pathways in the coupled climate–social system | Nature

Countries, states, companies, and individuals have shown to be very slow – and sometimes outright hostile and resistant – when it comes to making the necessary changes and adjustments. What little progress we have seen comes mainly through voluntary action or because the green alternative is also economically advantageous (e.g. renewable energy is cheaper than fossil fuel-based energy). The vast majority of people and companies in high-emitting countries have not experienced any inconvenience, let alone hardship, related to decarbonization.

While we need to continue to aggressively push for decarbonization it is naive at best to assume that we can “just” change people’s attitudes and behaviors fast enough to achieve the necessary emission reductions. It is equally unrealistic to assume we will enact and enforce laws that severely restrict the use of fossil fuels.

The COVID pandemic provides an instructive example. Despite data that unambiguously show that vaccinations have short-term, personal benefits (not needing emergency care, not dying) about one in three people in the US are not fully vaccinated and vaccine mandates have been fought all the way to the Supreme Court. If encouraging rational behavior (getting vaccinated) has such a high failure rate for something of fairly immediate personal benefit, the chances of successfully and quickly changing behavior about something as abstract and intangible as climate change are very slim at best.

We have to do both

Saying that we have to decarbonize and only once that is done start removing CO2 is creating a false dichotomy. They are not mutually exclusive and there is no reason why we can’t do both in parallel.

Both actions support each other and have the same goal: dramatically reducing CO2 concentrations in the air. Importantly, they are actually synergistic with decarbonization focusing on not making things worse and CDR on cleaning up the mess we already made.


We need to decarbonize and invest in CDR. The longer we wait to get a portfolio of different CDR methods off the ground, the more expensive it will be, or–worse–we will not succeed in scaling up quickly enough, with catastrophic consequences.


“[W]hat we need to do is integrate carbon removal as a part of our decarbonization and adaptation efforts. For if we have the newfound capacity to remove carbon from the atmosphere and put it elsewhere, do we not have the responsibility?”

Professor Holly Jean Buck, University of Buffalo [Link]

“All pathways that limit global warming to 1.5°C with limited or no overshoot project the use of carbon dioxide removal (CDR) on the order of 100–1000 GtCO2 over the 21st century.”

Special Report: Global Temperature Change of 1.5 C – A Summary for Policymakers, C.3. (2018)[Link]

“Unless affordable and environmentally and socially acceptable CDR becomes feasible and available at scale well before 2050, 1.5°C-consistent pathways will be difficult to realize, especially in overshoot scenarios.”

Special Report: Global Temperature Change of 1.5 C – Chap. 4 Strengthening and Implementing the Global Response (2018). [Link]

Contrary to claims that carbon removal is fundamentally at odds with other strategies, we can spend the next decade simultaneously deploying available clean energy technologies and scaling up removal strategies.

We can also move past the debate over whether we have all the technologies we need. Pilot-scale and commercial projects exist for almost all emissions sources, even for harder-to-abate ones. We’re unlikely to reach ambitious goals like net-zero emissions without making use of all technology and policy tools at our disposal and without continued investments in research and development.
Opinion | We Can Limit Global Warming if We Don’t Waste Time – The New York Times

“To become climate-relevant, the formative phases for air filter systems and other novel methods of carbon removal need to be at least as active as the fastest historical analogs. This will require more serious commitments toward novel removal technologies than are currently in place. The required levels will only be feasible if we see substantial development of novel CDR’s formative phase in the next 15 years.”

Gregory Nemet