About SRM

In 2025, the global average temperature recorded its highest level in observational history, and the warming trend is accelerating beyond previous projections. To achieve the "1.5°C target" set by the Paris Agreement, reducing greenhouse gas (GHG) emissions (mitigation) and preparing for climate change impacts (adaptation) remain top priorities. However, we are confronted with the reality that these measures alone are insufficient to halt extreme weather events and irreversible ecological changes.

Under these circumstances, we have entered a phase where discussions on a third option, "Climate Intervention," are unavoidable. At the center of this is Solar Radiation Modification (SRM). While this field was once considered taboo to even discuss, as the prospect of overshooting the 1.5°C target becomes increasingly realistic, open global discussions have begun to scientifically evaluate its risks and benefits, and to explore its potential for safe deployment.

SRM is a scientific approach that seeks to directly curb atmospheric temperature rise by artificially reflecting a portion of incoming sunlight back into space to adjust the Earth's energy budget, rather than reducing atmospheric GHG concentrations. The Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report and the "Special Report on Global Warming of 1.5°C" (SR1.5) primarily list the following methods:

• Stratospheric Aerosol Injection (SAI): A method that involves injecting particles, such as sulfur dioxide, into the stratosphere to artificially create a cooling effect similar to that of a volcanic eruption, thereby blocking sunlight.
• Marine Cloud Brightening (MCB): A method that involves spraying sea salt or other particles into low-level marine clouds to increase their reflectivity (albedo), thereby reducing the amount of solar radiation reaching the surface.
• Cirrus Cloud Thinning (CCT): A method that reduces the optical thickness of high-altitude cirrus clouds, allowing more heat (longwave radiation) from the Earth's surface to escape into space, thereby mitigating the greenhouse effect.
• Ground-Based Albedo Modification: A method that directly increases surface reflectivity through practices such as whitening roofs, altering land-use management, or covering deserts and glaciers with highly reflective materials.

While SRM attracts attention for its immediate efficacy and economic potential, the international community has called for extremely cautious deliberation due to the unknown risks posed by large-scale, uniform interventions. The IPCC Special Report on 1.5°C (SR1.5 SPM C.1.4) points out the following challenges regarding SRM:

• Large uncertainties and knowledge gaps: Although theoretically potentially effective, there is a lack of sufficient knowledge regarding physical processes and side effects.
• Risk of severe side effects: Global-scale interventions, particularly SAI, could trigger changes in precipitation patterns and atmospheric circulation, potentially leading to regional droughts or monsoon disruptions.
• Governance and ethical constraints: There are substantial institutional and social constraints to deployment, including international consensus on who governs the Earth's thermostat (governance), ethical issues, and impacts on sustainable development.
• Absence of a fundamental solution: While SRM can lower temperatures, it does not reduce atmospheric CO2 concentrations, which are the direct cause of ocean acidification.

Not all SRM is uncontrollable and dangerous. At the forefront of the scientific community, a new approach is gaining traction, one that operates on a "localized, optimized, and reversible" basis grounded in physical evidence, rather than the "uniform and irreversible interventions" of the past.

This is the paradigm of "Controlled SRM" (CSRM) advocated by this site. Recent studies indicate that by combining precise calculations with advanced material technologies, it is possible to achieve targeted effects while minimizing side effects.

• Optimization of deployment area and theoretical backing: Munday (2019) [1] theoretically deduced that deploying specific highly reflective sheets over just 1-2% of the Earth's surface could halt global warming. This suggests that a "precise intervention" over a calculated area is effective, rather than blindly whitening the entire globe.
• Suppression of side effects through high-resolution modeling: In ongoing cutting-edge research (Fukazawa et al.) [2], high-resolution Global Climate Models (GCMs) are being used to identify the "optimal placement locations and patterns" that can maximize the temperature reduction effect.

CSRM aims for responsible climate intervention by eliminating uncertainties as much as possible and ensuring "reversibility," allowing for immediate removal or cessation if any adverse effects are anticipated.

[1] Munday, J. N. (2019). Tackling climate change through radiative cooling. Joule, 3(9), 2057-2060. https://doi.org/10.1016/j.joule.2019.07.010
[2] Fukazawa, K., Suzuki, S., Sakoda, S., Miyoshi, Y., Osugi, R., & Suemitsu, M. (2025, December 16). Numerical Experiments of Atmospheric Temperature Changes due to Specific Land Surface Conditions [Poster presentation]. AGU25 Annual Meeting, New Orleans, LA, United States. https://agu.confex.com/agu/agu25/meetingapp.cgi/Paper/1871692

This site is not a promotional medium that blindly advocates for specific technologies. Rather, it is a platform that provides highly transparent information by curating the latest academic papers and global policy-making processes from a neutral perspective on the complex and critical issue of SRM.

Can "Controlled SRM" serve as a viable lifeline to save us from the climate crisis? Where do its scientific boundary conditions lie?

Together with policymakers, investors, and researchers worldwide, we aim to contribute to the creation of rules (the establishment of governance) for safe climate intervention for the next generation through sound, data-driven dialogue.