By Shuchi Talati, Union of Concerned Scientists
More than four years ago in Paris, the international community agreed to limit global average temperatures from rising beyond 2 degrees Celsius above pre-industrial levels, and that all efforts should be taken to limit them to below 1.5 degrees.
This was a critical step forward in acknowledging the immediate need to tackle the climate change crisis worldwide. If we exceed 1.5 degrees of warming, there will be more extremely hot days, higher seas, an almost complete loss of coral reefs, vast permafrost melt, and a steep decline in crop yields—just to name a few of the consequences. Beyond the 2-degree threshold, these impacts are far worse.
Right now, our emissions put us on a trajectory to endure at least 3 degrees of temperature rise before the end of the century. To divert us from this dangerous path, we should be working toward achieving net-zero global warming emissions by midcentury, but how do we get there?
Meeting this incredibly challenging goal requires widespread deployment of renewable energy, energy efficiency, and electric vehicles—all of which need a re-designed, modern power grid. Another key component for achieving net-zero is carbon removal. This describes a set of approaches that capture carbon from the atmosphere and subsequently use or store it, leading to negative emissions.
There’s incredible diversity among these approaches in terms of their readiness for deployment, economic costs, benefits and trade-offs.
Carbon removal is a process that happens naturally in an array of land and ocean ecosystems, like forests or wetlands. Enhancing these natural systems could help remove carbon faster from the atmosphere and also offer co-benefits to aid ecosystems in adapting or recovering.
These natural methods include planting trees, restoring wetlands, and enhancing the uptake of carbon by soils.
There has also been increased research and development around technological carbon removal. One such method is direct air capture, an engineered system to capture carbon directly from the air. This carbon can then be stored in geologic formations—that could last for thousands of years—or be used for fuel or building materials.
The Intergovernmental Panel on Climate Change (IPCC)—the United Nations body that periodically assesses the science behind climate change—released a special report on 1.5 degrees in 2018 explicitly stating that a portfolio of negative emission approaches will be needed if we are to limit temperatures in line with what is called for in the Paris Agreement. The U.S. National Academies of Sciences, Engineering, and Medicine also released a recent report acknowledging the importance of carbon removal and detailed how to move these approaches forward.
These might sound like “silver bullet” solutions, but carbon removal alone can’t save us. While it’s absolutely necessary to help address this massive problem, it is only one part of a portfolio of solutions that will help us cope with the threats from climate change.
The scale at which we need carbon removal is massive—on par with the largest endeavors ever undertaken in human history. And if we aren’t simultaneously investing in mitigating future emissions, the scale is even higher. Getting to that scale will take time, likely decades.
We don’t have that much time to avoid the inevitable effects of climate change. That means we also have to massively invest in adaptation measures and try to limit as much harm as possible.
Different carbon removal methods can have issues with permanence, cost and resource use. For example, afforestation, a natural carbon removal process cannot offer long-term storage of carbon because of factors like wildfires and logging.
Forests are an essential carbon sink, but wildfires will release large amounts of carbon dioxide into the atmosphere should those trees burn.
Planting trees is an important endeavor to reforest logged areas, maintain important sinks, and help the plants and animals that depend on forest ecosystems, but there’s not enough open land to plant enough trees to solve the carbon problem.
Carbon removal technologies face other issues. Direct air capture is still in the early stages of development and deployment, and is very expensive. Significant amounts of energy are required to run these systems, which in turn depends on resources like water and land.
There are many carbon removal approaches, but using them will require us to ask ourselves complex questions about what is scientifically and technologically needed, as well as what costs and risks we’re willing to accept.
A diverse portfolio — used in tandem with strategies to rein in emissions and protect affected communities — is necessary to address our changing climate.
Ultimately, without massive political and social reform we won’t be able to hit net-zero by 2050. Are we up for the challenge?
Shuchi Talati, Ph.D., is the Geoengineering Research Governance and Public Engagement Fellow at the Union of Concerned Scientists.
“The Invading Sea” is the opinion arm of the Florida Climate Reporting Network, a collaborative of news organizations across the state focusing on the threats posed by the warming climate.