Governments have previously sought to reduce climate-change-inducing concentrations of carbon dioxide in the earth's atmosphere through mitigation and adaptation activities, with limited success. New approaches are being explored, such as negative emissions technologies, including carbon dioxide removal, as well as solar geoengineering, also known as solar radiation management, or modification. This article outlines these emerging technologies focusing on bioenergy, carbon capture and storage, and stratospheric aerosol injection, and explores some of the challenges they pose. Prevention of emissions and their reliable, safe, and environmentally benign removal remain the best options. Robust governance systems and a careful, unbiased, and knowledge-driven assessment of the risks of these emerging technologies are required before they are implemented any further.
Klaus Radunsky received his PhD in Analytical Chemistry and Physics from the University of Vienna. He helped establish the Austrian Background Air Quality Monitoring Network in 1975, moving to the Environment Agency in 1985, where he remained until 2014. He has been the Austrian representative in a range of UNFCCC-related bodies and has had a long-term involvement in the country's greenhouse gas and national emission inventories. He is currently chair of the “mirror committee” at Austrian Standards (ASI) to the International Organization for Standardization's working group on greenhouse gas monitoring and management (ISO/TC 207/SC 7). ORCID iD:
Tim Cadman is a graduate of Girton College at the University of Cambridge, and a Research Fellow in the Institute for Ethics, Governance and Law at Griffith University. His research focuses on the governance of sustainable development, including forest management, climate change, finance, and institutional mapping (https://climateregimemap.net). His climate-related books include Climate Change and Global Policy Regimes: Towards Institutional Legitimacy (2013) and Governing the Climate Change Regime: Institutional Integrity and Integrity Systems (2016). ORCID iD: