Why We Need to Have Broad-Based Societal Discussions of the Governance of Geoengineering, at national and international levels, starting with scientists and increasingly with policy makers?

The Paris Agreement aims to limit the global temperature rise to 1.5 to 2°C above preindustrial temperature, but achieving this goal requires much higher levels of mitigation than currently planned. This challenge has focused greater attention on climate geoengineering approaches, as part of an overall response starting with radical mitigation. Geoengineering cannot address climate change on its own, but some scientists say that it could delay or reduce the overshoot. In so doing, we may expose the world to other serious risks. There is , however, no comprehensive international framework for governing these emerging technologies. Carbon dioxide removal technologies can have serious environmental, social and economic impacts, which need to be addressed. The largest immediate risk, however, could be the unilateral deployment of solar engineering by one country, a small group of countries, or a wealthy individual. The real or perceived impacts of deployment, including geopolitical reactions, could further destabilize a world already going through rapid change. Effective global governance frameworks could reduce this risk. SRM research is in its infancy. The real challenges are not technical, but pertain to ethics and governance. Should there be a strategic research programme, coupled with a global agreement to prohibit deployment unless and until certain risks and governance questions are adequately addressed? How would the world's governments determine if the potential global benefit of geoengineering is worth the risks to certain regions? How should trans-border and trans-generational issues be addressed? How would governance frameworks withstand geopolitical changes over decades or more of deployment? How might such technologies be developed and deployed without undermining political will to cut emissions? The world is heading to an increasingly risky future and is unprepared to address the institutional and governance challenges posed by these technologies. Geoengineering has planet-wide consequences and must therefore be discussed within intergovernmental institutions, including the United Nations. The research community has been addressing many of these issues, but the global policy community and the public largely have not. It's time to do so.