Geoengineering
Geoengineering is the deliberate large-scale interventions in the Earth’s climate system intended to counteract human-caused climate change. The term commonly encompasses two broad categories: large-scale carbon dioxide removal and solar radiation modification. CDR involves techniques to remove carbon dioxide from the atmosphere and is generally considered a form of climate change mitigation. SRM aims to reduce global warming by reflecting a small portion of sunlight (solar radiation) away from Earth and back into space. Although historically grouped together, these approaches differ substantially in mechanisms, timelines, and risk profiles, and are now typically discussed separately. Some other large-scale engineering proposals—such as interventions to slow the melting of polar and alpine ice—are also sometimes classified as forms of geoengineering.
Some types of geoengineering present political, social and ethical issues. One common objection is that focusing on these technologies could undermine efforts to reduce greenhouse gas emissions. Effective governance and international oversight are widely regarded as essential.
Major scientific organizations have examined the potential, risks, and governance needs of geoengineering, including the US National Academies of Sciences, Engineering, and Medicine, the Royal Society, the UN Educational, Scientific and Cultural Organization, and the World Climate Research Programme.
Governance
Most governance issues relating to geoengineering are specific to the category or the specific method. Nevertheless, a couple of international governance instruments have addressed geoengineering collectively.The Conference of Parties to the Convention on Biological Diversity have made several decisions regarding "climate related geoengineering." That of 2010 established "a comprehensive non-binding normative framework" for "climate-related geoengineering activities that may affect biodiversity," requesting that such activities be justified by the need to gather specific scientific data, undergo prior environmental assessment, be subject to effective regulatory oversight. The Parties' 2016 decision called for "more transdisciplinary research and sharing of knowledge... in order to better understand the impacts of climate-related geoengineering."
The parties to the London Convention on the Prevention of [Marine Pollution by Dumping of Wastes and Other Matter] and its associated London Protocol have addressed "marine geoengineering." In 2013, the parties to the London Protocol adopted an amendment to establish a legally binding framework for regulating marine geoengineering, initially limited to ocean fertilization and requiring assessment and permitting before any activity proceeds. This amendment has not yet entered into force due to insufficient ratifications. In 2022, the parties to both agreements acknowledged growing interest in marine geoengineering, identified four techniques for priority review, and encouraged careful assessment of proposed projects under existing guidelines while considering options for further regulation. In 2023, they cautioned that these techniques could pose serious environmental risks, highlighted scientific uncertainty about their effects, urged strict application of assessment frameworks, and called for broader international cooperation. Their work is supported by the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection of the International Maritime Organization.