The Role of Geoengineering among Climate Strategies
Robert E. Kopp, Rutgers University
Humans are conducting a massive experiment with Earth’s climate, extracting billions of tonnes of carbon that have been buried in sediments for millions of years and, by combusting them to power our energy system, injecting them into the atmosphere and ocean. Most scientific and policy discussions addressing climate change have focused on mitigation and adaptation -- changing economic behaviors that emit CO2 to reduce emissions, and acting to limit damages caused by a changing climate. But an increasing interest in geoengineering approaches has been spurred both by skepticism about whether society will embark upon significant mitigation in a timely basis and concern about potential "tipping points" leading to effectively irreversible changes in the Earth system.
Geoengineering strategies fall into two main categories: carbon dioxide removal (CDR), which accelerates the removal of carbon dioxide in the atmosphere (for example, by capturing atmospheric CO2 either biologically or chemically and then burying it) and solar radiation management (SRM), which reduces the amount of incoming solar radiation that makes it to Earth's surface (for example, by dispersing aerosols in the stratosphere).
CDR is slow, costly, and probably a crucial part of strategies to limit global warming to 2°C. SRM is fast and arguably low-cost; requires constant maintenance; involves human takeover of an additional, previously unmanaged component of Earth's climate system; has different distributional impacts than carbon-driven climate change; and involves a different set of risks and uncertainties. SRM cannot substitute for mitigation and carbon dioxide removal, and it raises new ethical and governance issues.
