Geoengineering Climate Change

I have been quite skeptical of geoengineering responses to climate change. I remain just as skeptical. I just don’t think it can even come close to working. It’s a moonshot to solve a problem no one actually wants to solve because of the sacrifices involved. The problem however is that at this point, the chances of us staving off catastrophic climate change that will cost billions of lives and well over half the species on the planet is quite remote, so the moonshot is now necessary. So, heck, might as well at least mention the ideas out there:

If the world wants to avoid catastrophic climate change, switching to a carbon neutral society is not enough. The Intergovernmental Panel on Climate Change (IPCC) has warned that limiting global warming to 1.5C by 2100 will require technologies such as DAC for “large-scale deployment of carbon dioxide removal measures” – large-scale meaning many billions of tonnes, or gigatonnes, each year. Elon Musk recently pledged $100m (£72m) to develop carbon capture technologies, while companies such as Microsoft, United Airlines and ExxonMobil are making billion-dollar investments in the field.

“Current models suggest we’re going to need to remove 10 gigatonnes of CO2 per year by 2050, and by the end of the century that number needs to double to 20 gigatonnes per year,” says Jane Zelikova, a climate scientist at the University of Wyoming. Right now, “we’re removing virtually none. We’re having to scale from zero.”

Carbon Engineering’s plant in Squamish is designed as a testbed for different technologies. But the firm is drawing up blueprints for a much larger plant in the oil fields of west Texas, which would fix 1 million tonnes of CO2 annually. “Once one is done, it’s a cookie cutter model, you simply build replicas of that plant,” says Oldham. Yet he admits the scale of the task ahead is dizzying. “We need to pull 800 gigatonnes out of the atmosphere. It’s not going to happen overnight.”

The science of direct air capture is straightforward. There are several ways to do it, but the one that Carbon Engineering’s system uses fans to draw air containing 0.04% CO2 (today’s atmospheric levels) across a filter drenched in potassium hydroxide solution – a caustic chemical commonly known as potash, used in soapmaking and various other applications. The potash absorbs CO2 from the air, after which the liquid is piped to a second chamber and mixed with calcium hydroxide (builder’s lime). The lime seizes hold of the dissolved CO2, producing small flakes of limestone. These limestone flakes are sieved off and heated in a third chamber, called a calciner, until they decompose, giving off pure CO2, which is captured and stored. At each stage, the leftover chemical residues are recycled back in the process, forming a closed reaction that repeats endlessly with no waste materials.

With global carbon emissions continuing to rise, the climate target of 1.5C is looking less and less likely without interventions like this.

“The number of things that would have to happen without direct air capture are so stretching and multiple it’s highly unlikely we can meet the Paris Agreements without it,” says Ajay Gambhir, senior researcher at the Imperial College Grantham Institute for Climate Change and an author of a 2019 paper on the role of DAC in climate mitigation.

The IPCC does present some climate-stabilising models that don’t rely on direct air capture, but Gambhir says these are “extremely ambitious” in their assumptions about advances in energy efficiency and people’s willingness to change their behaviour.

“We’re past the point where reducing emissions needed to take place,” says Zelikova. “We’re locking in our reliance on DAC more and more.”

I don’t really know how to respond to this other than just shrugging my shoulders and figuring we might as well try. What else do we have?