Short & Sweet - Our very basic CDR FAQ

Here is some foundational info in short form for anyone getting ready to engage with CDR skeptics, opponents & newbies. If you’ve wrapped your head around these basics, you are ready to start talking about CDR.

What is Carbon dioxide removal (CDR)?

A range of existing and proposed methods and technologies that support the removal of excess carbon dioxide from the atmosphere and its durable storage in geological, biological or manufactured materials, on land or in the ocean.

Why do we need CDR?

We have emitted too much CO2 into the atmosphere (think of it as waste in gas form) and continue to add more. During the past 800,000 years, CO2 levels never exceeded 300 parts per million. Since the industrial revolution, CO2 levels have risen dangerously high to 418 parts per million and continue to rise. We need CDR to remove all the excess CO2 waste that has accumulated and the CO2 we will continue to emit until we can fully decarbonize.

Why isn’t decarbonization enough?

Decarbonization, which means stopping further CO2 waste by not burning any more fossil fuels such as coal, oil, and natural gas. It is existentially important to decarbonize, but it is not enough. It will take many years to fully decarbonize. And even if we stopped adding CO2 emissions now, we would still have excess gigatons (billions of tons) of CO2 that we need to remove from the atmosphere.
To draw a comparison to CDR, If our streets were littered with 150 years of garbage, it wouldn’t be enough to say, “let’s stop adding litter.” We’d need to remove the existing litter to improve sanitation and public health.

How much CO2 do we need to remove?

Estimates from the IPCC suggest that 100 – 1,000 billion metric tons (Gigatons or Gt) of carbon dioxide removal will be needed over the 21st century for the world to limit global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels (identified as a critical target threshold under the 2015 Paris Agreement). Extensive analysis has found that scenarios achieving 1.5°C included carbon removal deployment by 2050 ranging from 1.3 to 29 gigatons of CO2 removal per year, with most falling between 5 and 15 gigatons. This massive level of carbon dioxide removal is in addition to the very aggressive measures we need to take to reduce humanity’s ongoing carbon dioxide emissions through the widespread adoption of renewable energy, conservation, and many other emissions reduction measures.

Should we decarbonize first and then implement CDR?

No, there isn’t enough time to take it slow anymore. Had we started decarbonization in earnest 50 years ago, we might have had that luxury. However, we are now running out of time and need to parallel-track decarbonization and CDR. Decarbonization and CDR are synergistic - not creating more CO2 waste and removing the existing waste. We have to do both. Carbon dioxide lingers in the atmosphere for centuries; so cleaning up what we already released is critical.

Trees are natural “CDR machines”. Can’t we just plant trees?

While we should plant a lot of trees and protect the ones we already have, that won’t be enough to solve our climate crisis. To remove even half of the CO2 we’ve already emitted, we’d have to cover the whole of the US or Europe with trees. We simply do not have enough land for an “all tree” solution.
We need trees plus many other forms of CDR.

What are some promising CDR solutions?

The answer to that question continues to evolve as new CDR methods are discovered, researched, developed and commercialized. OpenAir’s regular weekly webinar This Is CDR is a great place to learn more about the full spectrum of options that are now beginning to emerge in the market, and our bi-weekly YouTube series CDR Horizons gives a great view of earlier stage academic explorations.
Here are some examples of promising solutions:

  • BECCS (Bioenergy with Carbon Capture and Storage) - Plants use CO2 to grow; wood, leaves, and roots are all made with CO2 from the air. If we grow plants specifically or use biomass from agriculture (e.g. corn stover), burn that for energy AND catch the CO2 the burning creates before it enters the atmosphere AND sequester it (that is burying it underground) we have removed CO2 from the atmosphere.

Or as the U.S. National Academies of Science, Engineering and Medicine describes it:


  • Blue Carbon - Instead of using plants on land to capture CO2, blue carbon uses marine and coastal plants such as kelp. These plants are very efficient at capturing CO2. Unlike BECCS, they do not get burned for energy. Once they die and sink to the ocean floor, the CO2 is effectively trapped there.


  • Enhanced Weathering - Works by accelerating the natural process of certain minerals in binding CO2. In nature, the process is slow. However, by grinding up the minerals (e.g. olivine, also known as peridot) that reaction can be greatly accelerated.

  • Direct Air Capture (DAC) - Instead of using plants to capture the CO2, DAC uses a chemical process. The CO2 is bound to a solid or liquid capture substance and “harvested” once it’s at capacity (that is “full”). The capture substance can then be reused and the CO2 sequestered or used similar to BECCS.

  • Ocean Alkalinity - Adding minerals such as ground-up limestone, basalt, or olivines increases the ability of seawater to bind CO2 from the atmosphere and remove it. This has the added benefit of counteracting the acidification of the oceans that leads to the destruction of ecosystems including coral reefs and marine life.

  • Biochar - Occurs when you heat biomass in the absence of oxygen (pyrolysis). The result is a granular, safe carbon substance that binds the carbon permanently and has advantages in agriculture such as improved soil quality.

Isn’t CDR going to cost a fortune?

There is a cost to implementing various CDR solutions, but the alternative of not taking action is more costly. Doing too little about climate change has already cost us $1.5 trillion because of wildfires, floods, hurricanes, etc. and will cost us another $14.5 trillion over the next 50 years in the US alone due to property damage, building more resilient infrastructure, rising insurance and mortgage costs, etc. (note: we need to reference this).
How much it will cost depends a lot on how aggressively we develop these solutions no and scale them up (which generally makes things a lot cheaper in the long run).

Shouldn’t we wait until CDR is proven and more mature?

No. Technology does not improve in a vacuum. Only if we invest will we be able to work on these different approaches to improve them, make them cheaper, and to develop new ones. The solutions we will be able to deploy in ten or twenty years will be vastly better and cheaper than what we have today IF we invest in them today.

What are examples of technologies that improved over time?

There are many but here are two interesting ones.

Cell phones - The first commercial cell phone in 1984 cost more than $10K. Talking for a minute was about $12 (in today’s dollars) and the devices weighed as much as a brick (2.5 lbs). At that time, didn’t we say “Oh forget it, we’ll never have cheap, truly portable phones?” Through technological innovation and scale, today we have phones that are more powerful than the supercomputers of the 80s (by a lot), cost a fraction, and fit into a pocket.

Solar panels - In the last decade the price of solar panels has come down by around 80% and efficiency has improved. That means that today you get a much more energy efficient solar panel for $20 compared to what was available in 2010 for $100.

There are many more examples of technological innovation that drove down costs with corresponding improvements in performance such as computers, 3D printing, driverless cars, …

Some people say CDR is a fossil fuel industry scam. Is that true?

No. CDR is urgently needed to combat climate change. That does not mean that the fossil fuel industry is not trying to manipulate it for their benefit. They may try to slow down decarbonization by advocating for solutions that capture CO2 emissions at the source, such as electric power plants.
We are aware of this and we can’t let that happen. It is a matter of the implementing the right policies and laws to promote decarbonization and CDR.

What is CCS and how is it different from CDR?

CCS stands for Carbon Capture and Storage and refers to capturing carbon from an emitting source, e.g. a smokestack instead of from the air (CDR). Sometimes it’s alternatively called CCSU where the U stands for “usage” which includes using the captured CO2.
While CCS uses some of the same technologies as CDR, it is fundamentally different because it relies on continued fossil fuel use to work. To capture CO2 from a smokestack you need an active smokestack. So, although its use lessens the impact of new emissions, it does not remove existing emissions which are far more abundant.

Isn’t CDR just “kicking the can down the road”?

Some CDR critics say that CDR is just kicking the can down the road because it helps us avoid doing the hard work of decarbonization.
Those assertions assume that CDR is meant to be a substitute for decarbonization. However, CDR should not be used to avoid/delay decarbonization; it needs to be deployed in addition to phasing out fossil fuels. In fact, not investing in CDR now is kicking that can down the road because the massive problem of all that CO2 that has already accumulated in the atmosphere from 150 years or so of burning fossil fuels is not at all addressed by decarbonization. Reliance on just decarbonization without CDR will cause climate change to continue to worsen and pass the ill effects onto our children and future generations.

Why do some people claim that CDR is not a real solution?

Some claim that CDR distracts from the real solution, namely decarbonization. There are many issues with this argument but primarily that it frames the discussion as an either-or decision.
Climate science and policy experts broadly agree that we need both rapid decarbonization and removal of CO2 from the atmosphere to avoid a climate catastrophe.

Doesn’t CO2 disappear by itself over time?

CO2 is very stable and once released it remains in the atmosphere for centuries or longer. Allowing excess CO2 to remain in the atmosphere will cause climate conditions to severely worsen in our lifetime and beyond.

Isn’t CDR untested and unproven?

CDR is not one technology, but many different approaches used to remove CO2 from the air. Planting trees, for example, is an important and proven form of CDR.
We need to differentiate between demonstrated vs commercial. Many CDR methods have been demonstrated on a small scale, so we know they work. The next - very challenging step - is to scale them up and make them commercially viable. That needs time and money. Government investment in solutions will help to accelerate economies of scale.

Isn’t CDR dangerous?

Removing CO2 from the atmosphere is not dangerous. Even for technical solutions such as DAC, the carbon capture itself is not dangerous.
There is some danger of leakage associated with transporting CO2 via pipelines and injecting it into geological storage. In high concentrations, CO2 is dangerous to humans and animals. So, great care needs to be taken to prevent leaks.