Geoengineering, also called climate engineering, is a group of technologies that are seeking to mitigate the effects of climate change by two methods. The first of these, CDR, stands for carbon dioxide removal. The second is SRM, or solar radiation management.
CDR technologies are trying to remove the excess carbon stored in the atmosphere–greenhouse gases and emissions. When businesses and activists talk about the “carbon footprint,” they are talking about the total carbon emissions from a human activity. Positive carbon footprints mean the excess carbon we produce is hanging over our heads, stuck in the atmosphere.
What exactly is geoengineering? Engineers are working on technologies that will slow or reverse the consequences of climate change. These are two basic types: carbon dioxide removal, or CDR—this tech removes emissions and greenhouse gases. The second type is solar radiation management, or SRM. This tech reduces the amount of solar energy warming the planet.
Two concerns are at the top of a long list of concerns regarding efforts to reduce or reverse climate change. Do we understand the effects of a single change introduced into a complex system? Does complexity itself predict that we cannot know the consequences of a single change introduced into a system of great complexity, such as the atmosphere of the earth?
Greenhouse gases, such as carbon dioxide, methane, and nitrous oxide are forming a warm blanket in the atmosphere that concentrates the energy of the sun, and keeps it radiating down toward earth, rather than diffusing back outward, as happened before the earth became industrialized. The Paris Accords are trying to set standards for stopping the consequences of the greenhouse gases warming the planet. They are hoping to reduce the warming by 1.5, or at most, 2 degrees. Even if we all began living car free and ate plant-based diets, stopped making trash and wasting food, it is too late to fix the atmosphere by just reducing emissions. The atmosphere will not be able to heal itself.
In order to stop the potentially catastrophic global climate changes that this heating of the earth is causing, and will cause, like a flaming snowball rolling down the hill, scientists and experts all agree that we must not just reduce emissions, but we have to get rid of some of the carbon already in the atmosphere. The CDR technologies are attempting to do that job.
Carbon dioxide is concentrated in some forms of growth on the planet, like trees and groups of plants, called biomass. These biomass carbon sinks are not considered stable enough, however, because the living tissues of the plants can die, and the carbon can be re-released back into the atmosphere by catastrophe such as wildfire. Some technologies propose sequestering the carbon and injecting it into the subsurface of the earth’s crust; theoretically, the carbon would remain stable. It’s not known, however, about the effects of a geologically active earth on these sequestered masses of carbon. Mineral mitigation is chemically combining carbon with mineral sources into a compound that cannot be broken down, and then storing that compound.
Bioenergy with carbon capture and storage, BECCS, is the only currently functioning CDR technology that is scaled for climate engineering. The technology uses biomass to remove and concentrate the carbon dioxide from the atmosphere. That biomass is then used as fuel to power industrial processes, and the carbon is sequestered and stored permanently, usually by injecting into the earth. This process is developing in scale large enough to actually make a dent in the carbon problem. Other technologies are still in research and development. But the basic steps- sequester the carbon, combine it with another chemical or mineral so it isn’t easily disrupted and moved back into the atmosphere, and find stable storage for the compound formed- are being used to develop new technologies.
These new CDR tech projects still in research and development must first work, and then be scaled to actually provide global climate engineering. The commitment to a project of this magnitude needs both long term political and social support, and long term financial support. Hopefully as understanding grows about the nature and scope of the problem, and how these technologies mimic natural processes, social and political support will grow and financial support will follow.