Geo-engineering (also spelled geoengineering, sometimes called climate engineering) refers to a set of proposed technologies that would intentionally alter the planet's climate at scale. The field is conventionally divided into two families:
- Solar Radiation Management (SRM): techniques that reflect a small fraction of incoming sunlight back to space. Prominent proposals include stratospheric aerosol injection (SAI), marine cloud brightening, and increasing surface albedo.
- Carbon Dioxide Removal (CDR): techniques that draw CO₂ out of the atmosphere, including direct air capture (DAC), bioenergy with carbon capture and storage (BECCS), ocean alkalinity enhancement, and large-scale afforestation.
CDR is recognized in the IPCC's Sixth Assessment Report (AR6, 2021–2022) as necessary in most pathways consistent with the 1.5°C target of the Paris Agreement (2015). SRM is treated more cautiously: the IPCC notes it could reduce some climate risks but introduces new ones, including termination shock, regional precipitation shifts, and governance challenges.
International governance is fragmented. The Convention on Biological Diversity adopted decisions in 2010 (COP-10, Nagoya) urging parties to ensure no climate-related geoengineering activities take place that may affect biodiversity, pending adequate scientific basis and risk assessment. The London Convention and London Protocol on marine pollution adopted a 2013 amendment regulating ocean fertilization, though it has not entered into force. There is no dedicated multilateral treaty on SRM.
Geo-engineering is politically contested. In March 2024, a Swiss-led resolution at the UN Environment Assembly (UNEA-6) on SRM was withdrawn after opposition from several states. Civil-society groups and a 2022 open letter signed by hundreds of academics have called for a non-use agreement on solar geoengineering, while other researchers argue for structured research programs. For Model UN delegates, the term commonly arises in UNEP, UNFCCC, and disarmament-adjacent committees referencing the 1976 ENMOD Convention, which prohibits hostile environmental modification.
Example
At UNEA-6 in Nairobi in March 2024, Switzerland withdrew a draft resolution that would have established an expert group on solar radiation modification after opposition from states including the United States and several African and Pacific nations.
Frequently asked questions
No. There is no comprehensive ban. The 1976 ENMOD Convention prohibits hostile environmental modification, the CBD has issued non-binding moratorium-style decisions since 2010, and the London Protocol regulates ocean fertilization, but peaceful research and deployment are not generally prohibited.
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