Geoengineering

Interest continues to grow in geoengineering, the controversial approach of directly manipulating the environment to combat climate change. Scientists have proposed projects to slow Antarctic ice melting using underwater plastic or air-bubble curtains to block warm water from reaching glaciers. Some environmental groups are getting on board; the Environmental Defense Fund has moved to fund research on the effects of reflecting sunlight into space as global warming intensifies. But local governments are showing caution; in June 2024, the Alameda, California, city council voted to stop scientists from spraying salt into the atmosphere as initial research into this solar radiation management strategy.

Carbon removal, a type of geoengineering that reduces the amount of carbon dioxide in the atmosphere, is a growing frontier in climate innovation. In 2024, the EU agreed to establish a certification process to better regulate these technologies, and in the U.S., the industry is advocating for more regulation to bolster confidence in the sector. Approaches being tested include capturing carbon emissions directly from industrial processes and using seawater to remove carbon from the atmosphere. One company is launching a large-scale initiative to "mineralize" carbon dioxide, transforming it into the industrial product calcium carbonate at a steel plant in Gary, Indiana. But carbon capture technology is not without concerns; the first underground commercial carbon sequestration plant built in the U.S. is leaking, worrying nearby residents. As these approaches are further developed and refined, planners should explore how and if carbon capture can be integrated into their local economies.

Solar radiation management (SRM), or technologies that reduce the amount of sunlight that reaches the ground, is the most controversial form of geoengineering. Methods proposed include marine cloud brightening through aerosols, cirrus cloud thinning to permit more heat escape from Earth, and sun shields in space and stratospheric aerosol scattering in the upper atmosphere that would reflect light away from Earth. Though the indirect effects of SRM are not well established, the Biden administration and the EU have signaled openness to the prospect of studying SRM, and NOAA has invested $22 million in SRM research. The debate over SRM largely stems from its unknown impacts, as well as the risk of termination shock it carries, whereby if its implementation were suddenly stopped, warming could accelerate to exceed current projections. Additionally, its effects would not be limited to one country's borders, so there is growing debate over how it should be governed and by whom. The international organization Degrees is currently working to confront these challenges by engaging with countries that would be most vulnerable to SRM.

While geoengineering at large is still the focus of much debate, forms of it have been in practice for some time. Trees bioengineered to grow more quickly and store more carbon are starting to move from concept to reality. Biotechnology company Living Carbon planted genetically modified poplar seedlings on public land in Georgia in 2023 and intends to plant upward of four million more, though critics have begun to voice concerns over the lack of multigenerational research into the modified trees and their interactions with other organisms over time. Cloud seeding is another in-use form of geoengineering that induces precipitation by "seeding" clouds with specialized mixtures of chemicals or other materials. While the practice has been used throughout the world for decades, it is expanding into new markets as crises around the availability of water, persistent drought, and desertification take hold. In the U.S., Nevada, Utah, Texas, Idaho, California, and New Mexico have all expanded their use of the technology, and Mexico has commissioned cloud-seeding firms to relieve persistent drought conditions in key areas. Planners should stay informed about the development and implementation of these global-impact technologies and their potential implications for local communities.