Negative Emission Technologies Won’t Save Us (yet)

And why we must proceed with caution.

Direct air capture technology. Credit: Carbon Engineering

By now, the dire situation we are in regarding carbon emissions and their contribution to a warming planet is not a secret.

We’re also familiar with what we can do at an individual level to reduce our footprint, namely implementing the Holy Trinity — flying and driving less, ditching the single-use plastic and reducing our meat consumption.

What’s less publicised is that these measures are unlikely to be enough to achieve the goals of the Paris Agreement — limiting warming to 2°C above pre-industrial levels by 2100 with efforts to reduce this to 1.5°C. We’re currently already at 1°C, with emissions rising in 2018 for the first time in four years. Even if all emissions stopped tomorrow morning, the level of carbon already in the atmosphere means that we would still miss these targets, by quite a long way.

In fact, warming projections for 2100 by Climate Action Tracker shows that a business-as-usual scenario — that is, if we were to do nothing about emissions — places us at 4.1– 4.8°C of warming. An analysis by Carbon Brief found that 4°C of warming would likely see economic damages from river flooding in the UK increase by 6,543% and the average drought length in North Africa rise to five years. That’s pretty rough by anyone’s standards.

The same study predicts that even with all the commitments and pledges, which are viewed as incredibly ambitious, the best we can do is a 2.6–3.2°C increase.

So, if cutting emissions isn’t enough, what can we do?

The answer being suggested, like so often, is technology. In short, we need to remove carbon that has already been emitted on top of continuing to pursue aggressive mitigation actions. Negative emissions technologies (NETs), in theory, allow us to undo some of the damage we have already done.

Source: World Resources Institute

These technologies vary widely. For example, afforestation and reforestation are perhaps the most natural, simply the planting of trees to increase carbon uptake. Others, not so much. Direct air capture — the photo at the top of this article — literally sucks the carbon out of the air and stores it underground.

While the methods differ and are all promising in theory (you can find a more detailed explanation of them here), they share the same pitfall — scalability. It’s estimated that we’d need to capture 20 billion tons per year in order to reach our target. At the moment, direct air capture and carbon capture and storage, the two technologies with the most potential, could possibly remove 5 billion tons each. But even these estimates are unreliable.

To make things worse, the cost of finding out the utility of these technologies is extortionate. In fact, direct air capture technology is so expensive that just three start-ups around the world have the technology and have only built demonstration sized projects so far. A study in 2018 found that it costs between $94 — $200 per ton. Even if it could remove the estimated 5 billion tons, which is highly unlikely, it doesn’t take a mathematician to tell you that it’ll cost a shitload.

However, it’s not the inability of the technology that is the danger. NETs are in their infancy and, like all technologies, will continue to develop. Rather, it’s how this technology is communicated that could derail climate efforts.

Moral Hazard

NETs run the risk of being presented as a silver bullet — an all-encompassing miracle technology that eliminates all of our carbon sins after we have committed them. If people buy this message that all emissions can simply be retrieved, individuals and decision-makers may stop pursuing actions that lead to aggressive emission reductions.

Misperceptions of the promise of carbon removal technologies can be leveraged as justifications for delaying actions and falling behind emission reduction schedules.

Modelling scenarios accounting for carbon retrieval technologies shows that emissions can remain as high as 32 gigatons in 2030 compared with 23 in the scenario without them. The 9 gigaton difference is equivalent to China’s annual emissions. If delays occur because we’re banking on NETs, and then they don’t work at the required scale, we end up with emissions far higher than without them entirely.

This is worrying because of human nature. Most people, myself included, are guilty of occasional laziness and the desire to take shortcuts. The danger is that these technologies are presented as just that — a shortcut. The last thing we need is an excuse to be even lazier than we have already been.

People are incentive driven. The incentive to reduce our emissions is to stop, or at least limit, the impacts of catastrophic weather events that could lead to forced displacement and loss of life (amongst many others), as well as to prevent future generations suffering from perpetual environmental anxiety. If people are presented with technology that claims it can simply retrieve their carbon emissions, the incentive for reduction disappears.

I fear there is a miscommunication as to the theory and reality of these technologies. The way they’re being portrayed reminded me of a quote by a great 21st Century philosopher (Ryan Gosling in The Big Short):

“I’m standing in front of a burning house, and I’m offering you fire insurance on it.”

Except in our scenario the house is in a wildfire, and the insurance might not pay out.


I don’t doubt that technology in the coming decades will develop to the unthinkable compared to what we have today, just like technology now was unthinkable in 1990. It’s not the technology itself that sparks fear. In fact, I think it’s vital that we keep exploring these technologies and urge those with the power and money to invest heavily in their research and development until they work at scale.

But we must tackle how we present them publicly. They need to be framed as a potentially useful supplement to mitigation rather than as an alternative, otherwise we’ll place our entire future on a hunch.

I’m not a gambling man but that seems like a shitty bet.