While we acknowledge that reducing greenhouse gas emissions offers a sustainable and long-term solution to climate change, we continue to see rising emissions. As some exacerbate climate challenges, others are exploring options that were once beyond the scope of mainstream discussion.

The term “geoengineering” broadly refers to human interventions in climate systems aimed at maintaining ecosystems and cooling the planet. Yet, the definition of geoengineering remains elusive; it can encompass endeavors from reforestation to the deployment of massive underwater curtains to support ice sheets.

Some geoengineering concepts spark more debate than others. Large-scale reforestation, when executed properly, is generally seen as a positive climate action. However, more radical ideas—like altering sunlight’s interaction with the Earth’s atmosphere—invoke heightened concerns.

“The risk-return dynamics vary significantly,” states Janice Lachance of the non-profit American Geophysical Union (AGU), which has recently introduced an “Ethical Framework” for scientists in this field. She elaborates, “Planting trees in a park is relatively straightforward and widely accepted. However, when we delve into novel technologies and methodologies, the situation rapidly shifts.”

Take, for example, the concept of solar radiation management (SRM), which proposes reflecting additional sunlight back into space to cool the planet. This can be approached in three fundamental ways (illustrated in the graphics below). Although early modeling suggests that SRM could yield cooling effects within just a few years of implementation, it may also disrupt rainfall patterns and cloud formation.

SRM has historically been a contentious area of research, but as temperatures climb and climate impacts intensify, it has garnered attention from scientists, policymakers, and philanthropists alike.

While some activists argue against this line of research, fearing it diverts focus from the urgency of rapid emission reductions, Andy Parker of the Degree Initiative—a nonprofit concentrating on SRM—cautions that merely reducing emissions may no longer suffice for humanity to tackle climate change’s consequences.

“We must explore strategies to manage the risks posed by previously released greenhouse gases,” he asserts. Moreover, without international dialogue on geoengineering, “there’s a heightened risk of individual nations—especially those severely affected by climate change—unilaterally pursuing geoengineering projects.”

In this context, an increasing number of scientists are advocating for geoengineering research. “Some researchers feel they are falling short in meeting the objectives outlined in the Paris Agreement,” notes Lachance. Consequently, the AGU has devised an ethical framework to guide climate intervention research.

The concerns regarding research extend beyond methodologies. Concepts of planetary-scale geoengineering often place developing nations—particularly those near the equator—at greater risk of unforeseen consequences, such as disruptions to monsoon patterns. Yet, the majority of geoengineering research is concentrated in wealthier countries, which have less to lose.

As part of the Degree Initiative, Parker collaborates with researchers from lower-income countries in the Southern Hemisphere to develop SRM research capabilities. He hopes this will ensure that future deployment decisions take into account the populations most affected. “We don’t hold a stance on whether SRM should be utilized or not,” he explains. “What we do want is for developing nations to have informed avenues for their own research.”