Table of Contents

Understanding Geoengineering in the Climate Crisis Era

Geoengineering represents one of the most controversial and potentially transformative approaches to addressing climate change in the 21st century. As global temperatures continue to rise and the impacts of climate change intensify, scientists, policymakers, and researchers are exploring deliberate, large-scale interventions in Earth's climate system to counteract warming trends. These technological interventions, while offering potential solutions to mitigate climate impacts, also carry significant implications for physical landscapes, ecosystems, and human communities worldwide.

The concept of geoengineering encompasses a broad spectrum of techniques designed to manipulate Earth's climate system at planetary scales. From reflecting sunlight back into space to removing carbon dioxide from the atmosphere, these approaches represent humanity's most ambitious attempts to engineer solutions to the climate crisis. However, the deployment of such technologies raises profound questions about environmental risks, governance challenges, and the potential for unintended consequences that could reshape physical landscapes in ways we are only beginning to understand.

Historically, the topic of geoengineering has been deeply controversial in the climate change community, with extreme hesitancy and taboo surrounding both scientific and governance engagement in the field. While there is still reticence, major institutions and organizations with strong influence are showing signs of a major shift in perception, activity, and interest over the last two to three years. This evolving landscape makes it critical to understand how these interventions might alter the physical world around us.

The Two Primary Categories of Geoengineering

Geoengineering techniques are generally divided into two distinct categories, each with fundamentally different approaches to addressing climate change and each carrying unique implications for physical landscapes and environmental systems.

Solar Radiation Management: Reflecting Sunlight to Cool the Planet

Solar geoengineering refers to proposed approaches to cool the Earth by reflecting solar radiation back to space. The two main approaches being researched are stratospheric aerosol injection (SAI) and marine cloud brightening (MCB). These techniques aim to reduce the amount of solar energy absorbed by Earth's surface and atmosphere, thereby lowering global temperatures without directly addressing the root cause of climate change.

Stratospheric Aerosol Injection (SAI) represents one of the most extensively studied solar radiation management techniques. For stratospheric aerosol injection (SAI), small particles would be introduced into the upper atmosphere to reflect sunlight and induce global dimming. This approach mimics the natural cooling effect observed after major volcanic eruptions, when sulfur dioxide particles are ejected into the stratosphere and temporarily reduce global temperatures.

The implementation of SAI would involve aircraft or specialized delivery systems dispersing aerosol particles at altitudes of approximately 20 kilometers above Earth's surface. These particles would remain suspended in the stratosphere for extended periods, scattering incoming solar radiation back into space before it can warm the planet's surface. While stratospheric aerosol injection (SAI) aims to cool Earth's surface by scattering incoming solar radiation, the strategy's impacts on cirrus microphysics remain poorly understood, potentially leading to unintended consequences.

Marine Cloud Brightening (MCB) offers a more localized approach to solar radiation management. MCB would involve spraying sea salt into low-lying marine clouds to enhance their brightness and reflectivity in order to increase regional-scale cooling. This technique leverages the natural properties of clouds to reflect sunlight, with the goal of increasing the albedo (reflectivity) of specific regions.

Very small droplets of sea water are sprayed into the air to increase cloud reflectivity. The fine particles of sea salt enhance cloud condensation nuclei, making more cloud droplets so making the clouds more reflective. Recent field experiments have begun testing this approach in real-world conditions. Outdoor MCB trials have been conducted since 2020, taking place in the vicinity of Big Broadhurst Reef off Townsville in Queensland in 2020 and 2022, over Heron Reef off Gladstone in Queensland in 2023, and over Gouda Reef, 500 km off the Queensland coast, in 2024.

Other solar radiation management techniques under consideration include cirrus cloud thinning, which aims to reduce the warming effect of high-altitude ice clouds, and surface albedo modification, which involves increasing the reflectivity of land surfaces through changes in land use, building materials, or vegetation cover.

Carbon Dioxide Removal: Extracting Greenhouse Gases from the Atmosphere

The second major category of geoengineering focuses on removing carbon dioxide directly from the atmosphere. Carbon dioxide removal (CDR) refers to strategies that remove CO2 from the atmosphere for long-term storage in reservoirs on land or in the ocean. CDR aims to draw down atmospheric CO2, thereby directly addressing the major underlying cause of climate change. Unlike solar radiation management, which treats the symptoms of climate change, CDR addresses the fundamental problem of excess greenhouse gases in the atmosphere.

As of 2023, CDR is estimated to remove around 2 gigatons of CO2 per year. This is equivalent to about 4% of the greenhouse gases emitted per year by human activities. There is potential to remove and sequester up to 10 gigatons of carbon dioxide per year by using those CDR methods which can be safely and economically deployed now. However, meeting global climate targets will require substantial scaling of these technologies.

The IPCC 6th Assessment Report (AR6) considers CDR to be a necessary component of successful strategies for limiting global warming to 1.5–2°C. The State of Carbon Dioxide Removal report (2nd Edition, 2024) estimates that 7–9 gigatonnes (Gt) CO2 removal will be required each year by 2050 to achieve the climate targets of the Paris Agreement.

Direct Air Capture (DAC) represents one of the most technologically advanced CDR approaches. DAC involves capturing carbon dioxide directly from the atmosphere. Although DAC is currently deployed mainly through pilot projects, it is expected to scale up rapidly, reaching around 90 million tonnes of CO₂ removal per year by 2030 and just under 1 gigatonne per year by 2050. These facilities use chemical processes to extract CO2 from ambient air, which is then compressed and either stored underground in geological formations or utilized in industrial processes.

The physical infrastructure required for direct air capture facilities can significantly impact local landscapes. Large-scale DAC plants require substantial land areas for equipment installation, energy generation facilities to power the capture process, and potentially extensive pipeline networks to transport captured CO2 to storage sites. A key challenge for DAC and DOR systems is the necessary high-energy inputs.

Bioenergy with Carbon Capture and Storage (BECCS) combines biological carbon removal with technological capture systems. BECCS integrates bioenergy generation with carbon capture, offering scalability and cost-effective potential, particularly in regions rich in forestry and geological storage infrastructure. This approach involves growing biomass crops that absorb CO2 from the atmosphere, burning that biomass for energy, capturing the CO2 released during combustion, and storing it underground.

The landscape implications of BECCS are substantial, as it requires large areas of land dedicated to growing energy crops. This can lead to competition with food production, changes in land use patterns, and potential impacts on biodiversity and ecosystem services.

Enhanced Weathering and Mineralization accelerate natural geological processes that remove CO2 from the atmosphere. Carbon mineralization can also be used to sequester carbon dioxide that's already been captured by injecting that CO2 into suitable rock types where it reacts to form a solid carbonate, permanently storing it. This approach involves spreading crushed silicate rocks over agricultural lands or coastal areas, where they react with CO2 in rainwater to form stable carbonate minerals.

Ocean-Based CDR Methods leverage the ocean's natural capacity to absorb and store carbon dioxide. Those are called ocean fertilization, ocean alkalinity enhancement, wetland restoration and blue carbon approaches. Ocean alkalinity enhancement, for example, involves adding alkaline substances to seawater to increase its capacity to absorb CO2 from the atmosphere. Alkalinity enhancement aims to increase the ocean's CO2 storage capacity by changing the chemistry of the sea water to encourage greater absorption of CO2 from the atmosphere.

Nature-Based Solutions include afforestation, reforestation, and wetland restoration. Conventional methods are those that are already well established and part of land-use change or forestry activities (e.g., reforestation/afforestation, wetland restoration, soil carbon). These approaches work with natural ecosystems to enhance their carbon sequestration capacity, offering co-benefits for biodiversity and ecosystem services while transforming physical landscapes through vegetation establishment and ecosystem restoration.

Direct Impacts on Physical Landscapes

The deployment of geoengineering technologies at scale would inevitably alter physical landscapes in numerous ways, ranging from subtle changes in microclimates to dramatic transformations of land use and ecosystem structure. Understanding these impacts is crucial for evaluating the full environmental consequences of geoengineering interventions.

Atmospheric and Climatic Alterations

Solar radiation management techniques would fundamentally alter the atmospheric conditions that shape physical landscapes. The introduction of aerosols into the stratosphere or the brightening of marine clouds would change the quality and quantity of sunlight reaching Earth's surface, with cascading effects on temperature, precipitation, and weather patterns.

Stratospheric aerosol injection impacts regional temperatures within a decade, while precipitation effects remain harder to detect due to climate variability. These changes in precipitation patterns could significantly affect erosion rates, sediment transport, and the formation and evolution of landforms. Regions that experience reduced rainfall might see decreased erosion and slower landscape evolution, while areas with increased precipitation could face accelerated erosion, landslides, and changes in river morphology.

The alteration of cloud cover through marine cloud brightening would affect not only regional temperatures but also the distribution of solar radiation across landscapes. Changes in cloud patterns influence evapotranspiration rates, soil moisture levels, and vegetation growth patterns, all of which play crucial roles in shaping physical landscapes over time.

Temperature changes induced by solar radiation management could affect permafrost stability in high-latitude regions, potentially slowing or accelerating the thawing processes that are currently reshaping Arctic and sub-Arctic landscapes. Similarly, changes in temperature and precipitation patterns could influence glacier dynamics, affecting rates of glacial advance or retreat and altering the landscapes shaped by glacial processes.

Land Use Transformation for Carbon Removal Infrastructure

Carbon dioxide removal technologies require substantial physical infrastructure that directly transforms landscapes. Direct air capture facilities, while more compact than some other CDR approaches, still require significant land areas for equipment, energy generation, and supporting infrastructure. The construction of these facilities involves land clearing, grading, and the installation of extensive mechanical systems, permanently altering local topography and land use patterns.

The energy requirements for DAC facilities necessitate either connection to existing power grids or the construction of dedicated renewable energy installations such as solar farms or wind turbines. These energy facilities themselves have substantial landscape footprints, requiring additional land clearing and infrastructure development that can fragment habitats and alter natural drainage patterns.

Storage of captured carbon dioxide requires access to suitable geological formations, typically deep saline aquifers or depleted oil and gas reservoirs. The infrastructure for transporting CO2 from capture facilities to storage sites includes pipeline networks that cross diverse landscapes, requiring rights-of-way, periodic maintenance access, and monitoring stations. The injection of CO2 into underground formations, while not directly visible at the surface, can potentially affect groundwater systems and, in rare cases, induce seismic activity that could impact surface landscapes.

Bioenergy with carbon capture and storage presents perhaps the most dramatic landscape transformation among CDR technologies. Some mitigation pathways propose achieving higher rates of CDR through massive deployment of one technology; however, these pathways assume that hundreds of millions of hectares of cropland are converted to growing biofuel crops. This scale of land conversion would fundamentally reshape agricultural landscapes, potentially displacing food production, altering biodiversity patterns, and changing the character of rural regions.

The cultivation of energy crops for BECCS involves establishing monoculture plantations of fast-growing species such as switchgrass, miscanthus, or short-rotation woody crops. These plantations replace diverse natural ecosystems or traditional agricultural landscapes with uniform vegetation stands optimized for biomass production. The resulting landscapes differ dramatically in structure, biodiversity, and ecological function from the systems they replace.

Coastal and Marine Landscape Modifications

Ocean-based carbon dioxide removal approaches would alter marine and coastal landscapes in various ways. Ocean alkalinity enhancement involves adding large quantities of alkaline materials to seawater, which could affect coastal sediment dynamics, water chemistry gradients, and the physical structure of coastal ecosystems.

The infrastructure required for ocean alkalinity enhancement includes facilities for processing and distributing alkaline materials, which would be located in coastal areas. These facilities would alter coastal landscapes through construction of processing plants, storage facilities, and distribution systems. The discharge of alkaline materials into coastal waters could affect sediment transport patterns, potentially influencing beach formation, coastal erosion rates, and the morphology of estuaries and lagoons.

Marine cloud brightening operations, while primarily affecting atmospheric conditions, require maritime infrastructure including specialized vessels or offshore platforms for generating and dispersing sea salt aerosols. MCB could be implemented using fleets of unmanned rotor ships to disperse seawater mist into the air. The deployment of such fleets would create new patterns of maritime activity and potentially affect coastal and near-shore environments.

Wetland restoration and blue carbon approaches, while generally beneficial for ecosystem health, nonetheless transform landscapes by converting degraded or developed coastal areas back to natural wetland systems. This restoration involves re-establishing tidal flows, removing infrastructure, and allowing natural sedimentation and vegetation succession processes to reshape coastal topography.

Enhanced Weathering and Landscape Modification

Enhanced weathering approaches involve spreading crushed silicate rocks across agricultural lands or other terrestrial surfaces to accelerate natural carbon sequestration processes. This technique directly modifies soil composition and structure, altering the physical and chemical properties of surface landscapes.

The mining, crushing, and transportation of rock materials for enhanced weathering creates its own set of landscape impacts. Quarrying operations remove rock from source locations, creating excavations and altering local topography. The processing of rock into fine particles requires industrial facilities that transform local landscapes, while the transportation of crushed rock to application sites involves extensive road networks and vehicle traffic that can affect soil compaction and erosion patterns.

The application of crushed rock to agricultural lands changes soil texture, drainage characteristics, and nutrient availability. Over time, as the rock particles weather and react with CO2, they alter soil chemistry and potentially affect plant growth patterns, erosion rates, and the movement of water through soil profiles. These changes can influence the evolution of agricultural landscapes and the ecosystem services they provide.

Effects on Erosion, Sedimentation, and Geomorphological Processes

Geoengineering interventions have the potential to significantly alter the fundamental geomorphological processes that shape Earth's surface. These changes operate through multiple pathways, affecting the rates and patterns of erosion, sediment transport, and landscape evolution.

Precipitation Pattern Changes and Erosion Dynamics

Solar radiation management techniques could alter precipitation patterns at regional and global scales, with direct consequences for erosion processes. Changes in rainfall intensity, frequency, and seasonal distribution would affect the erosive power of water on landscapes. Regions experiencing reduced precipitation might see decreased rates of water erosion, potentially allowing vegetation to establish in previously barren areas and stabilizing slopes that were formerly subject to active erosion.

Conversely, areas receiving increased precipitation could experience accelerated erosion, particularly if rainfall intensity increases. More intense rainfall events generate greater surface runoff, increasing the capacity of water to detach and transport soil particles. This could lead to increased gully formation, accelerated hillslope erosion, and higher sediment loads in rivers and streams.

The spatial redistribution of precipitation could create new patterns of erosion and deposition across landscapes. Watersheds that become wetter might experience increased stream power and channel incision, while those that become drier could see reduced sediment transport capacity and increased deposition in channel systems. These changes would gradually reshape valley morphology, floodplain characteristics, and the overall structure of drainage networks.

Temperature Effects on Physical Weathering

Temperature changes induced by geoengineering would affect physical weathering processes that break down rock and contribute to landscape evolution. Freeze-thaw cycles, which are particularly important in high-latitude and high-altitude environments, depend on temperatures fluctuating around the freezing point of water. Changes in the frequency and intensity of freeze-thaw cycles would alter rates of frost weathering, affecting the production of sediment and the breakdown of rock surfaces.

In permafrost regions, temperature changes could accelerate or slow the thawing of frozen ground, with profound implications for landscape stability. Permafrost thaw leads to ground subsidence, the formation of thermokarst features, and increased sediment availability for erosion and transport. The rate of these processes would be directly influenced by temperature changes resulting from geoengineering interventions.

Thermal expansion and contraction of rock surfaces, driven by daily and seasonal temperature variations, contribute to rock breakdown through thermal stress weathering. Changes in temperature ranges and patterns would alter the effectiveness of these processes, potentially affecting the rate at which rock surfaces degrade and contribute sediment to erosion systems.

Vegetation Changes and Landscape Stability

Geoengineering-induced changes in temperature, precipitation, and solar radiation would affect vegetation patterns, which in turn influence erosion and sedimentation processes. Vegetation plays a crucial role in stabilizing landscapes by protecting soil surfaces from raindrop impact, reducing surface runoff velocities, and binding soil particles with root systems.

Changes in vegetation cover resulting from altered climate conditions would affect erosion rates across diverse landscapes. Areas where vegetation becomes more sparse due to reduced precipitation or changes in growing conditions would become more vulnerable to erosion. Conversely, regions where vegetation cover increases might experience reduced erosion rates and greater landscape stability.

The conversion of land to energy crop production for BECCS would replace natural vegetation communities with managed agricultural systems. These monoculture plantations typically provide less effective erosion control than diverse natural ecosystems, particularly during establishment phases when ground cover is incomplete. The regular harvest of biomass removes vegetation that would otherwise protect soil surfaces, potentially increasing erosion vulnerability during certain periods of the crop cycle.

Coastal Erosion and Sediment Dynamics

Geoengineering interventions could affect coastal erosion processes through multiple mechanisms. Changes in storm frequency and intensity, influenced by altered atmospheric conditions, would affect wave energy reaching coastlines and the erosive power of coastal storms. Sea level rise, which geoengineering might slow but not reverse, interacts with these changes to influence coastal erosion rates and patterns.

Ocean alkalinity enhancement and other marine CDR approaches could affect coastal sediment dynamics by altering water chemistry and potentially influencing the behavior of sediment particles in coastal waters. Changes in the chemical composition of seawater might affect the flocculation and settling of fine sediments, potentially altering patterns of sediment deposition in estuaries, deltas, and coastal wetlands.

The restoration of coastal wetlands as a carbon removal strategy would transform coastal sediment dynamics by re-establishing natural patterns of sediment trapping and accretion. Wetland vegetation slows water movement, promoting sediment deposition and gradually building up coastal landscapes. This process would counteract erosion in some areas while potentially affecting sediment supply to adjacent coastal systems.

Ecosystem and Biodiversity Impacts on Landscapes

The physical structure of landscapes is intimately connected to the ecosystems they support, and geoengineering interventions that affect ecosystems will consequently alter landscape characteristics. These changes operate through complex interactions between biological communities and physical processes.

Habitat Fragmentation and Landscape Connectivity

The infrastructure required for large-scale geoengineering deployment would fragment natural habitats and alter landscape connectivity. Direct air capture facilities, pipeline networks, energy crop plantations, and associated infrastructure create barriers to wildlife movement and divide continuous habitats into isolated patches. This fragmentation affects not only biodiversity but also the ecological processes that influence landscape evolution.

Fragmented landscapes experience altered patterns of seed dispersal, pollination, and nutrient cycling, which can affect vegetation composition and structure. These changes in vegetation patterns subsequently influence erosion rates, soil development, and other physical processes that shape landscapes over time.

The conversion of large land areas to energy crop production for BECCS would create extensive monoculture landscapes that differ fundamentally from natural ecosystems in their structure and function. These simplified landscapes typically support reduced biodiversity and altered ecological processes, with consequences for landscape stability and resilience to disturbances.

Soil Ecosystem Alterations

Geoengineering interventions can affect soil ecosystems, which play crucial roles in landscape processes. Enhanced weathering approaches directly alter soil chemistry and structure by adding crushed rock materials. These changes affect soil microbial communities, which are essential for nutrient cycling, organic matter decomposition, and the formation of soil structure.

Changes in soil ecosystems influence the physical properties of soils, including their resistance to erosion, water-holding capacity, and ability to support vegetation. Soils with altered microbial communities may develop different structural characteristics, affecting their vulnerability to erosion and their role in landscape evolution.

The cultivation of energy crops for BECCS affects soil ecosystems through agricultural practices including tillage, fertilization, and pesticide application. These practices can reduce soil organic matter content, alter soil structure, and affect the biological communities that contribute to soil formation and stability. Over time, these changes influence the physical characteristics of agricultural landscapes and their susceptibility to erosion and degradation.

Aquatic Ecosystem Changes and Landscape Effects

Geoengineering-induced changes in aquatic ecosystems can affect the physical characteristics of water bodies and associated landscapes. Altered precipitation patterns would change stream flows, lake levels, and groundwater recharge rates, affecting the geomorphological work performed by water in shaping landscapes.

Changes in aquatic vegetation communities, influenced by altered water chemistry or temperature conditions, would affect sediment dynamics in rivers, lakes, and wetlands. Aquatic plants stabilize sediments, influence flow patterns, and affect the deposition and erosion of materials in aquatic environments. Changes in these vegetation communities would alter the physical evolution of aquatic landscapes.

Ocean-based CDR approaches that alter seawater chemistry could affect marine ecosystems in ways that influence coastal landscape processes. Changes in the abundance or distribution of organisms that contribute to sediment production, such as coral reefs or shellfish beds, would affect the supply of biogenic sediments to coastal systems and the physical structure of coastal landscapes.

Regional and Local Climate Modifications

While geoengineering is often discussed in terms of global climate effects, the implementation of these technologies would create regional and local climate modifications that directly affect physical landscapes in specific areas.

Microclimate Alterations from Infrastructure

The physical infrastructure of geoengineering systems creates local microclimate modifications that affect surrounding landscapes. Large direct air capture facilities alter local wind patterns, temperature distributions, and humidity levels through their physical presence and operational characteristics. These microclimate changes can affect vegetation growth, soil moisture patterns, and erosion processes in areas immediately surrounding the facilities.

Energy crop plantations create distinct microclimates compared to the natural ecosystems or agricultural systems they replace. Monoculture stands of tall grasses or woody crops alter wind patterns, shade distribution, and evapotranspiration rates, creating different temperature and moisture conditions at ground level. These microclimate changes affect soil processes, erosion rates, and the potential for other vegetation to establish in and around the plantations.

Solar farms and wind turbine installations required to power CDR facilities create their own microclimate effects. Solar panels alter surface albedo, temperature, and the distribution of precipitation reaching the ground beneath them. Wind turbines affect local wind patterns and can influence temperature and moisture distributions in their vicinity. These microclimate modifications affect the physical and ecological characteristics of landscapes where renewable energy infrastructure is deployed.

Regional Precipitation Redistribution

Solar radiation management techniques could redistribute precipitation at regional scales, creating areas that become wetter or drier relative to current conditions. Solar geoengineering could "introduce a widespread range of new risks to people and ecosystems, which are not well-understood", the IPCC's scientists said in their latest assessment of climate science. These regional precipitation changes would have profound effects on landscape evolution and the physical characteristics of affected regions.

Regions experiencing increased precipitation would see enhanced erosion, greater sediment transport in river systems, and potentially increased landslide activity on steep slopes. Landscapes in these areas would evolve more rapidly, with more active geomorphological processes reshaping surface features. Increased water availability might also support expanded vegetation cover, which could partially offset increased erosion potential.

Areas receiving reduced precipitation would experience decreased erosion rates and slower landscape evolution. However, reduced water availability could lead to vegetation loss, potentially increasing erosion vulnerability despite lower rainfall. These regions might see increased wind erosion as vegetation cover declines and soil surfaces become more exposed to wind action.

The boundaries between regions experiencing different precipitation changes would create transition zones where landscape processes shift over relatively short distances. These transition zones might experience particularly dynamic landscape evolution as ecosystems and physical processes adjust to changing conditions.

Temperature Gradient Modifications

Geoengineering interventions could alter temperature gradients across landscapes, affecting the distribution of climate zones and the physical processes associated with different temperature regimes. Changes in temperature gradients would influence the elevation of treelines in mountainous regions, the extent of permafrost in high latitudes, and the distribution of climate-sensitive landforms.

Mountain landscapes are particularly sensitive to temperature changes because they encompass multiple climate zones within relatively small geographic areas. Shifts in temperature gradients would move these climate zones upslope or downslope, affecting the distribution of vegetation, the extent of glaciers and snowfields, and the rates of physical weathering processes at different elevations. These changes would alter the character and evolution of mountain landscapes.

In polar and subpolar regions, temperature changes would affect the extent and stability of permafrost, with cascading effects on landscape processes. The boundary between permafrost and seasonally frozen ground is particularly dynamic, and shifts in this boundary would create zones of active landscape change as ground ice melts and previously frozen sediments become available for erosion and transport.

Unintended Consequences and Landscape Risks

The deployment of geoengineering technologies at scales sufficient to affect global climate carries inherent risks of unintended consequences that could significantly impact physical landscapes in unexpected ways.

Termination Shock and Rapid Landscape Change

One of the most significant risks associated with solar radiation management is the potential for "termination shock" – a rapid warming that would occur if geoengineering interventions were suddenly stopped after being deployed for an extended period. There are also questions about how long this technology would be needed and what happens after it is stopped. This rapid temperature increase could trigger accelerated landscape changes as systems that had adjusted to artificially cooled conditions suddenly faced much warmer temperatures.

Permafrost regions that had remained stable under geoengineering-cooled conditions could experience rapid thaw, leading to widespread ground subsidence, thermokarst formation, and massive releases of previously frozen sediments. Glaciers that had achieved temporary stability might undergo rapid retreat, dramatically altering glaciated landscapes and downstream systems dependent on glacial meltwater.

Ecosystems that had adapted to geoengineering-modified conditions might be unable to adjust quickly enough to rapid warming, leading to widespread vegetation die-off and associated increases in erosion and landscape instability. The combination of rapid climate change and ecosystem collapse could trigger cascading landscape changes that would be difficult to predict or manage.

Unexpected Interactions with Natural Systems

Geoengineering interventions could interact with natural climate variability and Earth system processes in unexpected ways, creating landscape impacts that were not anticipated in modeling studies. As clouds are complicated and poorly understood, the risks of marine cloud brightening are unclear as of 2025. The complexity of Earth's climate system makes it difficult to predict all potential consequences of large-scale interventions.

Interactions between geoengineering-modified atmospheric conditions and natural phenomena such as El Niño events, monsoon systems, or atmospheric circulation patterns could create regional climate anomalies with significant landscape impacts. These interactions might produce extreme weather events, prolonged droughts or wet periods, or unusual seasonal patterns that affect landscape processes in ways that differ from both current conditions and predicted geoengineering effects.

The chemical and physical changes introduced by geoengineering could trigger feedback loops in Earth systems that amplify or modify intended effects. For example, changes in vegetation patterns resulting from altered precipitation could affect surface albedo and evapotranspiration rates, creating additional climate feedbacks that influence landscape evolution in unexpected ways.

Cumulative and Synergistic Effects

The deployment of multiple geoengineering approaches simultaneously, or the interaction of geoengineering with other human activities affecting landscapes, could create cumulative and synergistic effects that are difficult to predict. The combination of solar radiation management and carbon dioxide removal, for instance, might produce landscape impacts that differ from the sum of their individual effects.

Geoengineering interventions would occur in a world already experiencing significant human impacts on landscapes through urbanization, agriculture, resource extraction, and other activities. The interaction between geoengineering effects and these existing pressures could create complex patterns of landscape change that are challenging to anticipate or manage.

Long-term cumulative effects of geoengineering on landscapes might not become apparent for decades or centuries. Gradual changes in erosion rates, sediment transport patterns, or ecosystem composition could slowly reshape landscapes in ways that only become evident over extended time periods. These long-term cumulative effects pose challenges for governance and decision-making, as the full consequences of geoengineering deployment might not be understood until long after implementation begins.

Governance, Research, and Future Directions

The potential for geoengineering to significantly alter physical landscapes raises important questions about governance, research priorities, and the path forward for these technologies.

International Governance Challenges

Switzerland is proposing to create the first United Nations expert group to "examine risks and opportunities" of solar radiation management (SRM), a suite of largely untested technologies aimed at dimming the sun. This initiative reflects growing recognition that geoengineering requires international coordination and governance frameworks.

Because solar geoengineering has global implications, its consideration as a climate response requires effective international governance. The transboundary nature of landscape impacts from geoengineering makes international cooperation essential. Changes in precipitation patterns, temperature distributions, or ecosystem dynamics in one region could affect landscapes in distant areas through atmospheric and oceanic connections.

Developing governance frameworks that adequately address landscape impacts requires input from diverse stakeholders including geomorphologists, ecologists, local communities, and indigenous peoples who have deep knowledge of landscape processes and changes. These frameworks must balance the potential benefits of geoengineering for climate mitigation against the risks of unintended landscape alterations and their consequences for ecosystems and human communities.

Research Funding and Priorities

Funding for high-risk solar geoengineering technologies has increased dramatically - more than tenfold between 2020 and 2025. As of 2025, 42% of research funding come from governments. Countries that have funded SRM research include the U.S., U.K., Australia, Argentina, Germany, China, Finland, Norway, and Japan, as well as the European Union.

Research priorities should include comprehensive studies of how geoengineering interventions would affect landscape processes across diverse environmental settings. This research should examine erosion and sedimentation dynamics, ecosystem-landscape interactions, and the long-term evolution of landscapes under various geoengineering scenarios. Understanding these impacts requires interdisciplinary collaboration between climate scientists, geomorphologists, ecologists, and social scientists.

Monitoring and verification systems are essential for detecting and understanding landscape changes resulting from geoengineering deployment. These systems should integrate remote sensing technologies, ground-based observations, and modeling approaches to track changes in landscape characteristics over time. NOAA's observational networks, modeling capabilities, and research programs position the agency to lead in evaluating the efficacy of CDR methods and their potential impacts on the marine ecosystem.

Small-Scale Testing and Landscape Monitoring

Proposals and plans to expand research in solar geoengineering now include initiatives to conduct small-scale atmospheric experiments in the US and in Australia's Great Barrier Reef. Even small-scale experiments with limited environmental and societal risk deserve significant public scrutiny and debate as they accelerate attention and legitimate concern about the potential for larger-scale, potentially riskier experiments, and possible deployment.

Small-scale field experiments provide opportunities to study landscape impacts under controlled conditions before any large-scale deployment. These experiments should include comprehensive monitoring of landscape processes including erosion rates, vegetation changes, soil characteristics, and hydrological patterns. The knowledge gained from small-scale studies can inform decisions about whether and how to proceed with larger-scale geoengineering interventions.

Long-term monitoring programs are essential for understanding the cumulative and delayed effects of geoengineering on landscapes. These programs should establish baseline conditions before any interventions and continue monitoring for decades to detect gradual changes in landscape characteristics. Such monitoring would provide early warning of unexpected impacts and inform adaptive management strategies.

Alternative Approaches and Complementary Strategies

Solar geoengineering would not address the root cause of climate change: emissions of heat-trapping gases, mostly from the burning of fossil fuels. It would not limit ocean acidification or the many harmful impacts on public health and the environment from fossil fuel use. This fundamental limitation underscores the importance of prioritizing emissions reductions and adaptation strategies alongside any consideration of geoengineering.

Analysis by WRI has shown that the most cost-effective and lowest-risk strategy for increasing carbon removal capacity involves developing and deploying a variety of approaches in tandem. Moving forward, diverse methods of carbon dioxide removal must be built into climate change strategies around the world to avoid dangerous levels of global warming.

Nature-based solutions that work with natural landscape processes offer opportunities to sequester carbon while providing co-benefits for ecosystems and landscape resilience. Reforestation, wetland restoration, and sustainable land management practices can remove CO2 from the atmosphere while enhancing landscape stability, biodiversity, and ecosystem services. These approaches typically have lower risks of unintended consequences compared to more technologically intensive geoengineering interventions.

Key Considerations for Landscape Impacts

Understanding the full scope of geoengineering impacts on physical landscapes requires consideration of multiple factors and perspectives:

  • Spatial Scale: Landscape impacts occur at multiple scales from local microclimate effects around infrastructure to regional precipitation changes to global alterations in temperature and atmospheric circulation patterns
  • Temporal Dynamics: Some landscape changes would occur rapidly following geoengineering deployment while others would emerge gradually over decades or centuries
  • Reversibility: Certain landscape changes might be reversible if geoengineering were stopped while others could represent permanent or long-lasting alterations to physical systems
  • Regional Variability: The same geoengineering intervention would produce different landscape impacts in different environmental settings depending on local climate, geology, vegetation, and existing human activities
  • Ecosystem Interactions: Landscape impacts cannot be separated from ecosystem changes as physical and biological systems are intimately connected
  • Cumulative Effects: Multiple geoengineering approaches deployed simultaneously or sequentially could produce cumulative impacts that differ from individual effects
  • Uncertainty: Significant uncertainties remain about many aspects of how geoengineering would affect landscapes, requiring precautionary approaches and adaptive management

Moving Forward: Balancing Climate Action and Landscape Protection

As the climate crisis intensifies and geoengineering moves from theoretical concept to active research and potential deployment, society faces difficult decisions about how to balance the urgent need for climate action against the risks of unintended landscape alterations. These decisions require careful consideration of scientific evidence, ethical principles, and the values of affected communities.

The physical landscapes of Earth have been shaped by natural processes operating over millions of years, creating the diverse environments that support ecosystems and human societies. Geoengineering interventions have the potential to alter these landscapes in fundamental ways, changing the physical characteristics that define regions and support life. Understanding these potential changes is essential for making informed decisions about whether and how to deploy geoengineering technologies.

Comprehensive assessment of landscape impacts should be integrated into geoengineering research and governance frameworks. This assessment should consider not only the direct physical changes to landforms and surface processes but also the broader implications for ecosystem services, cultural landscapes, and the relationship between human communities and their physical environments.

The path forward requires continued research to better understand potential landscape impacts, development of robust governance frameworks to guide decision-making, and meaningful engagement with diverse stakeholders who would be affected by landscape changes. It also requires maintaining focus on the fundamental solution to climate change: rapid and deep reductions in greenhouse gas emissions that address the root cause of the problem rather than treating its symptoms.

For more information on climate change mitigation strategies, visit the Intergovernmental Panel on Climate Change. To learn about carbon dioxide removal research, explore resources from NOAA's Climate Program Office. For perspectives on geoengineering governance, see the United Nations Environment Programme. Additional research on solar radiation management can be found through the Geoengineering Monitor. Information about nature-based climate solutions is available from the World Resources Institute.

The question of geoengineering and its effects on physical landscapes ultimately reflects broader questions about humanity's relationship with Earth's natural systems. As we consider interventions at planetary scales, we must carefully weigh the potential benefits against the risks of fundamentally altering the physical world that sustains us. The landscapes of tomorrow will be shaped by the decisions we make today about how to respond to the climate crisis.