What is carbon removal?
Carbon removal takes the gas form of carbon in the atmosphere (carbon dioxide) and transforms it into a solid. The natural carbon cycle already does this by storing carbon in carbon sinks such as trees, plants, soils, rocks, and the ocean. Chemistry rocks! (sorry)
But (just in case you’ve been living under one of the aforementioned rocks) we have been pumping unsustainable amounts of carbon into the atmosphere, while simultaneously removing carbon sinks via deforestation and mono-crop agriculture. The oceans are soaking in way more carbon than they should, leading to the build-up of carbonic acid (ocean acidification) and thus the bleaching of coral reefs.
We’ve already warmed the Earth by around 1 degree Celsius above pre-industrial levels. Recent reports from the Intergovernmental Panel on Climate Change (IPCC) suggest that we are on track to exceed 1.5 degrees between 2030 and 2035. At this point, strategies to reduce emissions - while still the most important part of mitigating climate change - will not be enough on their own. And, an increase of 1.5 degrees (while better than 2 or 4 degrees) will still have major impacts, the beginning of which we are already experiencing. So while rapid decarbonization is and should remain priority number one, carbon has been accumulating in the atmosphere for the past 200 years, and we need to address those historical emissions too.
We need to remove 10 gigatons of atmospheric carbon per year, increasing to 20 gigatons per year by 2100 on a global scale. There are many types of carbon removal, each with its own social, economic, and environmental risks if done poorly.
Carbon removal vs carbon capture
A quick caveat: carbon removal is not necessarily the same as carbon capture or carbon storage (CCS), at least not in the way these terms are used at fossil-fueled power plants. CCS technology can help to reduce the amount of carbon dioxide flowing into the atmosphere, but not all of it. Carbon removal reduces the amount of carbon dioxide already in the atmosphere by pulling it directly from the air and rendering it benign.
Types of carbon removal
Natural carbon removal
First, we can nudge along natural processes and let the trees and soil do their thing through reforestation and no-till agriculture. But we can’t just go planting trees willy-nilly because impacts of climate change also include an increase in wildfires. If we plant trees where they are likely to burn, all that carbon is released into the atmosphere again, and we’re back at square one. Furthermore, planting more trees requires land, which could be used for agriculture instead to provide enough calories for a growing population (there are lots of ways to grow food on less land in a more sustainable way, but that’s another Explainer).
Carbon removal technology
Direct air capture is big carbon removal machines or giant vacuum cleaners that capture carbon dioxide out of the air, compress it, and put it into the ground. Cool! The future is now! But, like your pet Roomba, direct air capture is expensive and requires a lot of energy. Companies buying carbon removal credits, or carbon offsets, would need to spend $600/ton on direct air capture technology versus 20 cents a ton on a renewable energy offset.
Marrying nature and technology
Other technological strategies enhance natural reactions between certain minerals and carbon dioxide.
Biochar is a highly porous material created when a piece of wood is burned without oxygen. When buried in the soil, bacteria concentrate around it, keeping more carbon in the ground while having the added benefits of improving agricultural productivity.
Mineral carbon capture takes a mineral that captures carbon naturally when exposed to the atmosphere on a geological scale. Scientists and startups are speeding up this process by crushing minerals to increase surface area and thus increase their ability to capture carbon. Carbon dioxide is concentrated more heavily in the ocean than in the air. Spreading these minerals in the ocean addresses ocean acidification and increases its capabilities as a carbon sink.
The issue is it’s hard to verify how much carbon was captured with these methods, unlike with direct air capture. Verification requires large-scale studies that are funded and regulated.
Who's working on carbon removal?
We can’t afford to put all our cheese curds on one poutine just yet, but we also don’t have time to hum and haw about different methods. Some will be more effective than others, but there isn’t a clear winner between the different options. We need to pursue carbon removal in any way we can while working on ways to verify and regulate it, which means investing in research and development now.
Sweden, the UK, and the US are positioned to be early leaders in carbon removal, with bills on the table to invest right now. The Department of Energy in the US has $6 billion from the bipartisan infrastructure bill to invest in carbon removal technology. Big Tech, including Stripe, Meta, and Shopify, are all teaming up to invest just under a billion dollars worth of carbon removal by 2030.
How can you support carbon removal initiatives?
Invest in carbon removal startups so that these different technologies can scale to the level needed, and scale in the right way. Learn more about carbon capture and carbon offsets through our conversations with Akshat Rathi. Listen to our episode with 776 fund fellow Laura Stieghorst, to learn about her company addressing ocean acidification through carbon removal, and then donate to her BASICO2 initiative.
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