American Geoengineering

As the pace of climate change outstrips the pace of emissions reduction, a growing number of scientists, engineers, and policymakers are turning to geoengineering — deliberate, large-scale interventions in the Earth's climate system — as a potential complement to decarbonization. American Geoengineering tracks the technologies, research programs, and policy debates shaping this emerging field in the United States.

What Is Geoengineering

Geoengineering encompasses two broad categories of climate intervention:

Solar Radiation Management (SRM)

Techniques that reflect a small percentage of incoming sunlight back into space to cool the planet:

• Stratospheric aerosol injection — Dispersing reflective particles (typically sulfur dioxide) into the upper atmosphere to mimic the cooling effect of volcanic eruptions
• Marine cloud brightening — Spraying sea salt aerosols into low-lying clouds over the ocean to increase their reflectivity
• Space-based reflectors — Deploying sunshades or mirrors at the L1 Lagrange point between Earth and the Sun

Carbon Dioxide Removal (CDR)

Technologies that pull CO₂ out of the atmosphere and sequester it permanently:

• Direct air capture (DAC) — Industrial facilities that use chemical sorbents or solvents to capture CO₂ directly from ambient air
• Bioenergy with carbon capture (BECCS) — Growing biomass, burning it for energy, and capturing the resulting CO₂
• Enhanced rock weathering — Spreading crusite silicate minerals on agricultural land to accelerate natural CO₂ absorption
• Ocean alkalinity enhancement — Adding alkaline materials to seawater to increase the ocean's capacity to absorb atmospheric CO₂

U.S. Research & Development

American universities, national laboratories, and startups are leading several major geoengineering research efforts:

• Harvard Solar Geoengineering Research Program — Conducting small-scale stratospheric experiments and modeling potential global impacts
• Climeworks and Heirloom — Direct air capture companies building commercial-scale facilities with DOE funding
• NOAA Climate Intervention Research — Federal research into the atmospheric science underlying solar radiation management
• DOE Carbon Negative Shot — A federal initiative aiming to reduce the cost of carbon removal to under $100 per ton

The Policy Landscape

Geoengineering raises profound governance questions. Who decides whether and when to deploy planetary-scale interventions? How are risks distributed across nations? What happens if deployment stops suddenly?

The U.S. is navigating these questions through a combination of federal research funding, interagency coordination, and engagement with international bodies. Bipartisan interest in carbon removal has grown steadily, while solar radiation management remains more politically contentious.

Why Follow This Field

• Climate urgency — Even aggressive emissions cuts may not prevent dangerous warming without active intervention
• Rapid innovation — Direct air capture costs have fallen dramatically and deployment is scaling
• Geopolitical implications — The ability to alter global climate raises questions of sovereignty and international law
• Career opportunities — A new interdisciplinary field combining atmospheric science, engineering, policy, and ethics

Stay informed as America grapples with the most ambitious engineering challenge in human history.