Their evidence is about unregulated geoengineering – governance repurposes geoengineering for good---it’s otherwise disastrous.

Facing such a future, nations are unlikely to stand idly by. They could decide to take matters into their own hands. What is to stop the government in Dhaka, for example, faced with the prospect of losing much of Bangladesh’s low-lying territory to the Indian Ocean, from purchasing jumbo-jets and spraying reflective aerosols into the stratosphere in hopes of reducing the absorption of sunlight? Nor will individuals remain on the sidelines. In 2012, an American scientist 100 tons of iron sulfate off the coast of British Columbia. The result was a massive phytoplankton bloom that absorbed atmospheric carbon and led to record salmon runs. How long before a progressive-minded billionaire seeks to do something similar on a far grander scale? Geoengineering is quickly moving from the radical fringe to the center of global public policy. In its October 2018 , the United Nations’ Intergovernmental Panel on Climate Change found no feasible pathway to keep average global temperature rise below 1.5 degrees Celsius—a target endorsed in 2015 at the Paris climate conference—without large-scale carbon dioxide removal. At last month’s U.N. Environment Assembly in Nairobi, Switzerland submitted a , co-sponsored by a dozen other countries, asking the U.N. Environment Program to “prepare an assessment of the status of geoengineering technologies.” Its purpose would be to establish criteria to define geoengineering; assess the scientific state of play; identify leading actors; summarize the potential risks, benefits, and uncertainties; and propose “global governance frameworks” for all of these things. The resolution failed within the consensus-based assembly. Such resistance is likely to crumble as the climate crisis worsens, however, and as more actors begin to freelance. Already, hundreds of scientists are conducting small-scale geoengineering experiments outside of public view and official supervision. Geoengineering could become a free-for-all, as uncoordinated governments and individuals take decisions with momentous implications for global security, prosperity and equity. Carbon dioxide removal, for instance, could place enormous demands on land, energy, water and oceans at the expense of biodiversity, food production, groundwater availability, soil quality and nutrient balance. Likewise, sweeping efforts to increase reflectivity of the atmosphere, clouds, land and oceans could alter regional and global weather patterns, temperatures, hydrological cycles, crop yields and development prospects. Solar radiation modification poses an additional dilemma: Because it does not actually reduce greenhouse gases, it must be continued in perpetuity—or at least until carbon removal has lowered CO2 levels. Given these risks, the world urgently needs a multilateral governance framework for geoengineering. Such an institution, or set of institutions, would permit sovereign nations to negotiate common standards and shared rules for forays into this uncharted territory. An immediate priority should be to improve transparency—a precondition for good governance. To this end, researchers from the Carnegie Endowment and Atlantic Council creating a central clearinghouse to collect and share data on geoengineering research and experiments, as well as to encourage protocols for public disclosure. Over the longer term, the U.N. system should move from simply sharing information about climate change to making rules, and enforcing them. A logical setting in which to launch negotiations is the U.N. Framework Convention for Climate Change. Member states can use its annual conference of parties to designate geoengineering a third pillar of climate risk management, alongside mitigation and adaptation. In parallel, the Intergovernmental Panel on Climate Change should expand its expertise on geoengineering. Stewart Brand of the Long Now Foundation in the 21st century, “humanity is stuck with a planet stewardship role.” But as it fails in that mission, humanity may be drawn, ineluctably, to become Earth’s engineers.