Removing Carbon From the Atmosphere Must Be Part of Climate Change Policy
The world has passed the point where reducing or even eliminating new carbon emissions is enough to avoid dangerous warming. It’s time to get serious about carbon removal technologies.
The Biden Administration’s commitment to taking action on climate change has brought new hope to those concerned about decisively addressing the issue. By rejoining the Paris Agreement and signing executive orders that make addressing climate change the responsibility of all government sectors, the United States is finally taking aggressive steps toward securing a sustainable future.
Unfortunately, over the last decade the world passed the point where simply reducing or even eliminating new carbon dioxide (CO2) emissions is enough to limit future warming to less than 1.5 degrees Celsius. In other words, too much CO2 is going into the atmosphere and not enough is coming out. Even if we stop burning fossil fuels today, tons of historical CO2 emissions sitting in the atmosphere will continue to warm the planet, causing dangerous climate conditions for at least another 1,000 years. Therefore, excess legacy CO2 must be removed from the atmosphere while we simultaneously stop adding new emissions.
To date, however, most of the discussion surrounding climate change has focused on eliminating current and future CO2 emissions, making the effort seem like a conventional pollution-prevention problem simply addressed by stopping unwanted substances from entering the environment. Indeed, in 2007 the US Supreme Court ruled that CO2 should be defined as an air pollutant under the Clean Air Act, treating CO2 the same as sulfur dioxide and other pollutants. Market-based approaches (specifically, emissions trading) successfully addressed the problem of acid rain in the United States in the late twentieth century, and have since become a favorite policy tool to address CO2 emissions as well. As a result, the Clean Power Plan of 2015 and the Affordable Clean Energy rule of 2018 focused only on reducing new CO2 emissions and did nothing about the accumulation of CO2 that has been building up over centuries—an oversight badly in need of correction.
We need to recognize climate change not only as a pollution problem, but as a cleanup and restoration problem by getting rid of unwanted accumulation and helping a damaged system recover. Dealing with past emissions will require removing CO2 from the atmosphere and storing it in a manner that won’t allow it to be easily emitted again—for example, underground or in the ocean, or converting it into long-lasting products like plastics and concrete. There are several technological, economic, and political challenges associated with removing CO2 from the air, and many strategies are being investigated that involve a variety of industrial processes as well as ocean-based and agricultural practices. Each has benefits, costs, and risks well worth investigating and discussing.
Among the most promising technologies being researched for carbon dioxide removal (CDR) is direct air capture (DAC), an engineered system that is getting attention and funding from the Department of Energy, thanks to the 2021 Consolidated Appropriations Act. DAC is technologically viable and already being commercialized around the world, but it is the most expensive of the CDR technologies. DAC removes CO2 directly from the air and is different from point-source carbon capture technologies that pull CO2 emissions out of industrial smokestacks or power-generating facilities as the emissions are being produced. In either case, new infrastructure will be required for transporting and storing CO2 after it is removed, along with regulations for keeping track of its movement and storage permanence.
Other methods of carbon removal may seem more familiar and ready to employ, but may have even greater caveats. Agriculture-based solutions involving plants or soils require a lot of land and raise concerns about natural ecosystems, land tenure, and food security implications. Ocean-based CDR tinkers with vast and insufficiently understood chemistry and biodiversity dynamics of marine ecosystems, thus also potentially affecting the human communities that rely on these ecosystems.
Moreover, there are few clear policies to guide and govern how and where CDR should be used, who may use it, how much CO2 it should remove, who should be responsible for or benefit economically from the removal, and how to manage unexpected harm resulting from these efforts. Developing policies to address these questions is just as important as demonstrating technological feasibility.
The science is overwhelmingly clear that in addition to significantly reducing or eliminating new CO2 emissions, we must also tackle the removal of past CO2 emissions from the atmosphere in order to stay within 1.5 degrees of warming, a goal that we are not currently on track to meet. The current US framing of climate change as an air pollution problem limits serious consideration and assessment of policy and technology innovations to only those that reduce new CO2 emissions. It’s time to recognize climate change mitigation as a two-part problem of preventing new CO2 emissions while simultaneously removing excessive atmospheric concentrations from past emissions, and we must move rapidly to adjust course.