Geoengineering is defined by the Encyclopedia Britannica as "the large-scale manipulation of a specific process central to controlling Earth's climate for the purpose of obtaining a specific benefit."
The idea of it has had a bit of an unspoken moratorium around it in the science community, but in recent years, it's been climbing back into conversations around climate change, prompting some to ask what measures could or even should be taken in order to rein in the impacts of global warming.
What exactly is geoengineering?
There are two types of geoengineering: carbon geoengineering, which basically looks to remove carbon dioxide from the atmosphere, and solar geoengineering, which looks to prevent a fraction of the sunlight hitting the earth in order to help cool the planet.
Both kinds are ethically fraught, but solar geoengineering is the one heating up a lot of debate online and at science conferences.
According to Harvard's Solar Geoengineering Research Program, this could look like thinning cirrus clouds in order "to emit more long-wave radiation from the Earth to space" or even using planes to scatter "tiny reflective particles" into the upper atmosphere in order to reflect sunlight back into space and keep the planet from heating up further.
"Frankly, my first reaction when I first heard that this existed was: 'You've got to be kidding. This sounds nuts,'" said Gernot Wagner, climate economist with the Columbia Business School and author of "Geoengineering: The Gamble." "So, the idea has been around forever, largely because volcanoes have been doing this forever."
In 1991, a stratovolcano in the Philippines, known as Mount Pinatubo, erupted to produce "earth's second largest eruption in more than half a century," according to the U.S. Geological Survey. In doing so, the volcano "produced the largest sulfur dioxide eruption cloud ever measured," expelling roughly 17 million metric tonnes of it into the atmosphere. Scientists say that massive dark eruption cloud ended up dropping the global temperature 0.5 degrees Celsius in the year that followed.
For a rapidly warming planet, that was a very big deal.
Basically, eruption clouds indicate to scientists that when reflective particles like "sulfate aerosols or calcium carbonate" scatter into the stratosphere, it could potentially help cool the planet.
But there lies a bigger question: Should we be applying it? Wagner says the answer to that lies in research.
"We think we know enough to be able to say, 'Yeah, it's worth studying further because there are potentially large net benefits of considering solar engineering as part of the climate policy portfolio,'" Wagner said. "Do we know enough to know whether to pull the trigger? Frankly, my answer would be we don't yet know enough. We need to do the research."
Critics of geoengineering argue that even research into the subject, never mind implementation, is the last thing we should be doing.
"I think what scares me the most is the power that comes with it, the very idea that a small group of people or nations or actors could actually have control over the global thermostat and actually be able to implement a technology that would affect every living thing on earth," said Lili Fuhr, deputy director of climate and energy program at the Center for International Environmental Law. "To actually manipulate global ecosystems at a planetary scale with irreversible harm and impact — that is something I find terrifying."
For Fuhr, concerns with geoengineering include its lack of a global governing body for it, the potential weaponization of it between countries, as well as the motivation behind some of those supporting it.
"Oil, gas and coal are profiting from that and using this as a shield and cover to expand their business, right now in the crucial years where we need to stop that expansion and start to phase out," Fuhr said.
Fuhr says there are also major concerns for termination shock if solar geoengineering is implemented. The idea of termination shock is that if the planet were to start and then suddenly stop solar geoengineering, the planet could potentially go through a whiplash that would see temperatures rapidly rise at a rate that could lead to catastrophic results.
Where does the U.S stand on geoengineering?
In 2022, Congress directed the White House Office of Science and Technology Policy to develop "an interagency working group" with groups like NASA, the National Oceanic and Atmospheric Administration and the Department of Energy to "manage near-term climate hazard risk and coordinate research in climate intervention." This group was also tasked with establishing a framework to "provide guidance on transparency, engagement, and risk management for publicly funded work in solar geoengineering research."