Meg More
Farmers Forum
There has been a lot of talk about geo-engineering, especially since billionaire Bill Gates has poured a lot of money into it. What is it? And should we be concerned?
This might sound like a science fiction movie. Geoengineering is the manipulation of the earth’s climate through large-scale interventions in the planet’s atmosphere, soils and oceans to combat global warming. Some people argue that we are playing with fire, that these strategies could backfire and we should stop trying to play God.
One of the most common strategies is solar geoengineering, designed to cool the earth by reflecting sunlight back into space. The leading proposed method is Stratospheric Aerosol Injection. This consists in spraying large amounts of reflective particles, usually sulfates (sulfur dioxide, hydrogen sulfide, sulfuric acid droplets,…) or aluminum oxide, into the atmosphere in order to block some of the sunlight from reaching the earth.
The earliest academic studies researching solar geoengineering date back to the 1970s. It wasn’t until 2006 that the topic became mainstream in the scientific community.
Since then, funding into solar geoengineering has risen dramatically, more than tenfold from 2020 to 2025. According to a study by the Heinrich Böll Foundation earlier this year, at least $128 million was spent on solar geoengineering globally in the last five years, although “real amounts are likely at least three to four times higher.” The money came mostly from philanthropic giving and government funding. In 2022, the U.S. government established a five-year research plan for solar geoengineering.
If conducted on a large-scale, Stratospheric Aerosol Injection would be done by planes spraying aerosols into the atmosphere. In a 2011 Stanford University seminar on energy, scientist David Keith described one way to do it: release sulfuric acid (H2SO4) directly “in the trail of an aircraft, and then it turns out you can control the particle size distribution really well.” Keith then added “It’s easy to do.” It is also inexpensive. Estimates suggest that a large-scale program utilizing modified commercial aircraft to spray sulfate aerosols would cost roughly $2 billion to $2.5 billion annually during its initial phases, and around $18 billion annually per degree Celsius of avoided warming.
Officially, this kind of geoengineering is only being conducted on a small scale. Since 2022, California-based private company Make Sunsets has been releasing sulfur dioxide into the atmosphere through balloons. An Israeli-American startup, Stardust Solutions, has received $75 million in funding to develop Stratospheric aerosol injection technology (the company’s CEO and Chief Product Officer used to work for Israel’s nuclear program). In a May interview with the New York Times, its CEO Yanai Yedvab revealed that Stardust is actively seeking patents and plans to eventually do outdoor testing through aircraft in collaboration with a government that would establish guidelines and parameters.
Solar geoengineering is facing a backlash from several different fronts: environmental justice advocates, academics, climate activists, Indigenous groups and governments. In fact, in 2023, after the California-based company Make Sunsets conducted two unauthorized experiments testing solar geoengineering technology in Mexico, the Mexican government banned all solar geoengineering experiments within its borders. In doing so, Mexico upheld the 2010 UN moratorium on geoengineering experiments.
Geoengineering has also been banned in Florida, Tennessee and Montana. Several other states have introduced similar bills. In July 2025, U.S. Congresswoman Marjorie Taylor Greene introduced the CLEAR Skies Act in the U.S. House of Representatives, a proposed federal bill that would criminalize intentional weather modification and geoengineering, including cloud seeding and stratospheric aerosol injection.
The main concerns related to geoengineering stem from the uncertainty surrounding its negative impacts. A 2024 brief by the Center for International Environmental Law stated that “As it is impossible to test geoengineering technologies for their intended impact on the climate except through large-scale deployment, geoengineering proposes turning the Earth into a laboratory, with the risk of locking in a wide range of harmful and potentially irreversible impacts.”
Project Drawdown, a non-profit organization for climate action, assessed the potential benefits and risks of solar geoengineering and concluded that “it could adversely impact atmospheric conditions, including damaging the ozone layer, and destabilize weather and rainfall patterns, with resultant harm to ecosystems, agriculture, and human well-being.”
In 2022, over 60 senior climate scientists and governance scholars from around the world called for an international ban on solar geoengineering. Today, over 630 academics from more than 60 countries have signed the open letter. The letter calls upon governments to ban outdoor experiments and deployment of solar geoengineering technologies, as well as ban public funding of geoengineering, and commit to not granting patent rights for technologies for solar geoengineering, such as modifying airplanes for aerosol injections.
There are other critics. There are those who believe that stratospheric aerosol injection is already happening large-scale, although secretly. They point to “chemtrails,” the white linear trails left by airplanes in the sky, and say that we are actively being sprayed with harmful chemicals without our consent. There is, however, no admission by any private company or government body in Canada or the U.S. or from the European Union that the aircraft plumes in the sky are solar geoengineering chemicals. The official view is that people are seeing condensation trails, that is, water vapour spewed from jet engines.
Yet all the patents, the funding, the will power, and the technology exist to carry out stratospheric aerosol injection. Proponents even acknowledge that geoengineering might kill people.
In 2013, leading proponent and University of Chicago scientist David Keith openly revealed in an MIT geoengineering debate that “If I made a decision or there was a collective decision to do a geoengineering program and you put, say, the kind of program I think makes more sense which is about a million tonnes (of sulfur dioxide) a year, you might end up killing many tens of thousands of people a year as a direct result of that decision.”
Keith launched Harvard’s solar geoengineering research program in 2017 and between 2008 and 2018 received $8 million from billionaire Bill Gates to run the Fund for Innovative Climate and Energy Research.
Reporter’s notes/sources:
Study: Who Funds and Who Pays: The funding of solar geoengineering, 2020–2025 Heinrich Boll Foundation
Brief: The Risks of Geoengineering: Accelerating Biodiversity Loss and Compounding Planetary Crises, Center for International Environmental Law
Open letter: Solar Geoengineering Non-Use Agreement
