Tech Review Explains: Let our writers untangle the complex, messy world of technology to help you understand what's coming next. You can read more here.

An American entrepreneur’s crude solar geoengineering effort in Baja California, first reported by MIT Technology Review in late December, has prompted widespread criticism—and now, the Mexican government plans to ban related experiments. 

Luke Iseman, previously a director of hardware at Y Combinator and the cofounder of a geoengineering startup, says he added a few grams of sulfur dioxide into a pair of weather balloons and launched them from an unspecified site somewhere on the Mexican peninsula last spring. He says he intended for the balloons to reach the stratosphere and burst under pressure there, releasing the particles into the open air. 

Scientists believe that spraying sulfur dioxide or other reflective particles into the stratosphere in sufficient quantities might be able to offset some level of global warming, mimicking the cooling effect from major volcanic eruptions in the past. But it’s a controversial field, given the unknowns about potential side effects, fears that even discussing the possibility could undermine the urgency to address the root causes of climate change, and the difficult questions over how to govern a technology that has the power to tweak the temperature of the planet but could have sharply divergent regional effects. 

Iseman acknowledged to MIT Technology Review, and other outlets that reported on the effort, that he didn’t seek scientific or government approval before moving forward with the balloon launches. He subsequently cofounded the startup, Make Sunsets, to commercialize the concept. The company previously said it had raised around $750,000 in venture capital and planned to sell “cooling credits” for particles released during future balloon launches. 

But on January 13, Mexico’s Ministry of Environment and Natural Resources announced that the government will prohibit and, where appropriate, halt any solar geoengineering experiments within the country. The agency noted that Make Sunset’s launches were done without notice or consent. It said the prohibition was motivated by the risks of geoengineering, the lack of international agreements supervising such efforts, and the need to protect communities and the environment. 

Mexico may be one of the first nations, if not the first, to announce such an explicit  ban on experiments, although many nations have existing environmental regulations and other policies that could restrict certain practices. It’s not clear from the statement that all research in the field would be prohibited, which can also include modeling and lab work. The press release also says Mexico will stop any large-scale solar geoengineering practices, which may mean large experiments or full deployment of the technology.

Representatives from the Ministry of Environment and Natural Resources and the government of Baja California couldn’t be immediately reached for comment.

'Indefinitely on hold'

Iseman, who didn’t respond to an inquiry from MIT Technology Review, told The Verge that future launches are “indefinitely on hold.” He said to the Wall Street Journal that he was “surprised by the speed and scope of the response” and had “expected and hoped for dialogue.”

But others weren’t surprised. Shuchi Talati, a scholar in residence at American University who is forming a nonprofit focused on governance and justice in solar geoengineering, warned in MIT Technology Review’s original piece that Make Sunsets’s actions could have a chilling effect on the field. She said the unauthorized effort could diminish government support for geoengineering research and amplify demands to restrict experiments.

Indeed, long-standing critics of geoengineering had seized on the news, saying Make Sunset’s efforts demonstrated that research is a slippery slope leading quickly to deployment. The Center for International Environmental Law applauded Mexico’s response and called on “all governments to take steps to ban solar geoengineering outdoor experiments, technology development, and deployment.”

Critics commonly claim that there’s already a moratorium on outdoor geoengineering activities under the UN’s Convention on Biological Diversity, an assertion repeated in the Mexican government’s statement. But geoengineering researchers have long said that this is a misreading. A 2016 paper highlighting “five solar geoengineering tropes that have outstayed their welcome” calls the claim “inaccurate on several counts.”

Geoengineering critics and researchers in the field alike criticized the decision to launch the balloons from Mexico, without approvals. The nation’s response “highlights the reckless way in which this company acted,” Talati said in an email. “To go to another country and conduct something akin to experimentation without consultation or engagement is unacceptable.” 

Iseman previously said he was motivated to launch Make Sunsets to combat the rising dangers of climate change. He had hoped forging ahead would help push forward a scientific field that, amid public criticism, has repeatedly encountered serious challenges to carrying out small-scale field experiments.

But geoengineering researchers are still grappling with what this episode, and the reaction to it, will mean for the field. 

A growing number of nations and universities have established formal research programs. In addition, a handful of scientists are working to move ahead with small-scale, controlled outdoor experiments related to geoengineering, including a Harvard group’s long-running efforts to conduct atmospheric balloon studies. Australian researchers have already carried out and obtained data from the first field experiments in marine cloud brightening, a separate approach that entails spraying salt particles to make coastal clouds more reflective.

As the idea has moved further into the scientific mainstream, it’s also sparked greater concerns. Early last year, dozens of scholars across a variety of fields called for an “International Non-Use Agreement on Solar Geoengineering.” It asks countries to ban outdoor experiments and prohibit national funding agencies from supporting the development of solar geoengineering technologies. 

'A strong humanitarian case'

But geoengineering researchers stress that they want to explore the potential of the technology because it could save lives—possibly many, many lives as heat waves, famines, wildfires, and other extreme weather events grow more common and severe in the coming decades. 

“Solar geoengineering could substantially offset global temperature rise and potentially offset serious secondary impacts, such as reduction in crop yields and increased frequency and intensity of hurricanes and typhoons,” wrote Holly Buck, the author of After Geoengineering: Climate Tragedy, Repair, and Restoration, in an MIT Technology Review op-ed arguing against the ban last year. “We don’t know everything about what it would do. But there is a strong humanitarian case for learning more.” 

Many also believe it’s inevitable that some nation or actor will carry it out regardless of the risks or the lack of an international consensus, given that it’s relatively cheap and easy to spray materials into the stratosphere. For this reason, some say it’s better to do research that could highlight the safest, most effective means of doing geoengineering or identify serious dangers before someone carries out large-scale releases.

“The need to understand the possibilities, limitations, and potential side effects of climate intervention becomes all the more apparent with the recognition that other countries or the private sector may decide to conduct intervention experiments independently from the U.S. Government,” wrote the authors of a 2017 report in which the US Global Change Research Program, which guides federally supported climate research, recommended geoengineering studies for the first time.

The main fear scientists articulated to MIT Technology Review is that Make Sunsets’s rudimentary balloon launches and attempts at commercialization will distort the perception of the field among the public and policymakers. 

“I think there’s a danger of painting serious scientists and careful experiments with the same brush as some dude that released some weather balloon and tried to make a buck off of it,” says Peter Irvine, a lecturer in climate change and solar geoengineering at University College London. 

“There are many of us who think seriously studying this idea … is worth doing, because it looks like it has the potential to substantially decrease the risk of climate change,” he adds. “We shouldn’t throw the baby out with the bathwater, and that’s the worry.”

However, Irvine adds that he’s not sure there has been or will be a chilling effect, noting that it’s not clear the government of Mexico had supported geoengineering experiments in the first place. He doubts that this incident alone would prompt the US federal government to backtrack on its plans to establish a research program and guidelines, or dissuade scientists from continuing to explore the field.

'A deep need'

A moratorium on deploying solar geoengineering is appropriate at this stage because we simply don’t know enough about it to move forward on large scales, says Gernot Wagner, a climate economist at Columbia Business School who has closely studied geoengineering issues. But he stresses that that’s also why it’s crucial to allow for research—to enable scientists to attempt to fill in those unknowns.

The consequences of the current controversy may not be all bad for the field.

Some hope the Make Sunsets incident and its aftermath will prompt more nations to establish clear rules guiding research efforts, or spur the development of international oversight agreements, for which there is a “deep need,” Talati says.

In addition, the overwhelmingly negative response to the company’s actions, the likely lack of market demand for its cooling credits, and the forceful response from Mexico may well discourage the formation of other for-profit solar geoengineering startups or unapproved, self-funded launches, other observers add. 

Still, most geoengineering researchers who MIT Technology Review interviewed agreed that a venture-capital-backed startup forging ahead in a foreign country without approval, striving to move fast and disrupt this area of research, was a terrible look. Many fear it could still exact a steep cost for public perceptions of a scientific field where it has already proved incredibly difficult to move forward on even the smallest experiments.