Geoengineering, also known as climate engineering, is the deliberate and large-scale intervention in the Earth’s natural systems to counteract climate change. It is generally divided into two main categories: Carbon Dioxide Removal (CDR) and Solar Radiation Management (SRM).

1. Carbon Dioxide Removal (CDR)

CDR focuses on addressing the root cause of climate change by removing greenhouse gases from the atmosphere. These methods are generally considered lower-risk but are often slow to act and expensive to scale.

• Afforestation and Reforestation: Planting trees on a massive scale to soak up carbon through photosynthesis.

• Direct Air Capture (DAC): Using large fans and chemical processes to pull CO2 directly out of the ambient air and store it underground.

• Ocean Fertilization: Adding nutrients like iron to the ocean to stimulate phytoplankton blooms, which absorb CO2.

• Bioenergy with Carbon Capture and Storage (BECCS): Growing crops for fuel, burning them for energy, and capturing the resulting CO2 before it reaches the atmosphere.

2. Solar Radiation Management (SRM)

SRM aims to reflect a small percentage of the sun's light and heat back into space. These methods do not reduce greenhouse gas concentrations, but they could potentially cool the planet very quickly.

• Stratospheric Aerosol Injection (SAI): Spraying tiny reflective particles (like sulfur dioxide) into the upper atmosphere to mimic the cooling effect of a large volcanic eruption.

• Marine Cloud Brightening: Spraying saltwater into low-lying sea clouds to make them whiter and more reflective.

• Space Mirrors: Placing giant mirrors or fleets of small shields in orbit to deflect sunlight before it reaches Earth.

Risks and Ethical Concerns

Geoengineering is highly controversial for several reasons:

• Moral Hazard: Critics fear that if we develop a "quick fix" for cooling the planet, governments and industries will stop trying to reduce carbon emissions.

• Termination Shock: If an SRM system (like aerosol injection) were started and then suddenly stopped (due to war, terrorism, or political shift), the planet could experience a decade's worth of warming in just a few years.

• Side Effects: Altering the atmosphere could change global rainfall patterns, potentially causing droughts in some regions while flooding others.

• Governance: There is currently no international agreement on who would "hold the thermostat" or how to compensate countries harmed by geoengineering side effects.

 

Geoengineering—the intentional large-scale manipulation of the environment to counteract climate change—involves a mix of academic researchers, private startups, and government regulators. As of 2026, the field is split between Solar Radiation Management (SRM), which aims to reflect sunlight, and Carbon Dioxide Removal (CDR), which pulls CO2​ from the air.

 

1. Academic & Research Institutions

These groups lead the scientific study and modeling of geoengineering risks and benefits

 

University of Chicago: Established the Climate Systems Engineering Initiative with dedicated funding to bolster research into interventions. Peter Irvine is a notable researcher here.  David Keith moved his research to the University of Chicago in 2023, where he will lead a program with up to ten faculty members studying geoengineering

 

Harvard University: The Harvard Solar Geoengineering Research Program (SGRP) is one of the most prominent hubs. Researchers like Peter Huybers, Robert Stavins, and Dustin Tingley lead interdisciplinary studies on the science and policy of climate intervention.

 

University of Cambridge: The Centre for Climate Repair hosts teams (including younger researchers like Yashas Raj and Jake Chapman) working on practical technologies like cloud-brightening nozzles for the Arctic and sea curtains to protect glaciers.

 

 

• David W. Keith is a professor in the Department of the Geophysical Sciences at the University of Chicago. He joined the University of Chicago in April 2023. Keith previously served as the Gordon McKay Professor of Applied Physics for Harvard University's Paulson School of Engineering and Applied Sciences (SEAS) and professor of public policy for the Harvard Kennedy School at Harvard University.^[2] Early contributions include development of the first atom interferometer (considered a major breakthrough in atomic physics) and a Fourier-transform spectrometer used by NASA to measure atmospheric temperature and radiation transfer from space.
• Kenneth Caldeira (born 1960) is an American atmospheric scientist. His areas of research include ocean acidification,^[2] climate effects of trees, intentional climate modification, interactions in the global carbon cycle/climate system, and sustainable energy. As of 2021, Caldeira is Senior Scientist in the energy research company Breakthrough Energy, Senior Staff Scientist (emeritus) in the Carnegie Institution for Science's Department of Global Ecology, and Professor (by courtesy) in the Stanford University Department of Earth System Sciences.
• Bill Gates has been a central figure in geoengineering for nearly two decades, primarily as a high-profile financial backer and advocate for what he calls an "insurance policy" for the planet. As of 2026, his involvement is characterized by long-term academic funding and a shift toward broader climate innovation through Breakthrough Energy.

  Major Funding & Projects

  While Gates doesn't manage these projects directly, his wealth has been the primary engine for several major initiatives:

  • FICER (Fund for Innovative Energy and Climate Research): Gates established this fund (managed by David Keith and Ken Caldeira) to provide grants for geoengineering research. It has been one of the few steady sources of private money for the field since 2007.

     

  • SCoPEx (Harvard): Gates provided the majority of the $12 million budget for the Harvard project. Despite the project’s official cancellation in 2024, Gates remains a vocal supporter of the need for such atmospheric research.

     

  • Carbon Engineering: Gates was an early investor in this direct air capture (CDR) company, which was later acquired by Occidental Petroleum for $1.1 billion. This represents his move toward "commercial" geoengineering.

  Current Focus (2026)

  In his recent 2026 updates, Gates has emphasized climate adaptation and Breakthrough Energy Ventures (BEV). While BEV focuses mostly on "green premiums" (making clean tech cheaper), he continues to support:

  • University Research: He remains a donor to the University of Chicago’s Climate Systems Engineering Initiative, which took in many of the researchers and goals from the former Harvard program.

  • Advanced Modeling: Much of his current funding is directed toward using AI and supercomputing to model the regional effects of solar geoengineering (e.g., how "dimming the sun" might affect monsoons in South Asia).

  Public Perception & Controversy

  Because of his involvement, critics argue that a single billionaire shouldn't have the power to fund a technology that affects the entire global atmosphere. Gates has pushed back, stating:

  "I’m not saying we should do it; I’m saying we should find out if it even works and what the side effects are."

  Summary of Role

• Gates Direct Action Financial Role Lead private funder for solar geoengineering research ($100M+ total across various entities).

• Key Allies David Keith (UChicago), Ken Caldeira (Breakthrough Energy). 
• Philosophy Viewing geoengineering as a "break glass in case of emergency" tool. 
• 2026 Status Pivoting toward institutionalized research at major universities rather than individual "rogue" experiments.

  

2. Private Startups & Commercial Ventures

A controversial but growing sector involves companies attempting to monetize geoengineering through "cooling credits" or venture-backed tech.

Make Sunsets: A California-based startup that made headlines for launching sulfur-dioxide balloons without government authorization, leading to bans in certain jurisdictions like Mexico.

Stardust Solutions: A U.S. and Israeli-based venture that has raised significant capital (reported around $60 million) to research and potentially deploy reflective materials.

SilverLining: A non-profit that works with researchers and policymakers to accelerate the study of rapid climate interventions.

 

3. Government & Regulatory Bodies

Governance is a major point of friction as nations struggle to decide who has the authority to "dim the sun."

NOAA (National Oceanic and Atmospheric Administration): In the U.S., NOAA is the primary agency with a statutory requirement to track "weather modification" activities, which include geoengineering. A recent 2026 GAO report highlighted the need for NOAA to strengthen its oversight as more organizations begin field research.

• The Office of Science and Technology Policy (OSTP)  

• EPA (Environmental Protection Agency): The EPA has been conducting internal reviews to determine its authority to regulate geoengineering activities, particularly as they scale up.

• UK ARIA (Advanced Research and Invention Agency): The UK's high-risk, high-reward research agency has recently allotted over £56 million for global research teams to study climate geoengineering.

• China: The Chinese government has long-standing, large-scale weather modification programs, and recent reports suggest significant integration of these capabilities with their military-civil atmospheric research.

   

   

4. International Platforms & Civil Society

• AGU (American Geophysical Union): Recently launched a platform to advance "responsible governance" for solar geoengineering research.

  SRM360: A non-profit focused on informing policymakers about the technical and ethical implications of solar geoengineering.
   

   

Summary of Approaches

Stratospheric Aerosol Injection (SAI), 

Cloud Brightening Startups

Commercial deployment Sulfur balloon launches