The slow pace of carbon emissions reductions and the increasingly obvious, devastating consequences of climate change make it imperative for the world’s governments to develop a broad portfolio of strategies to manage climate risk. That portfolio currently includes three main strategies, all of which will be discussed at the upcoming United Nations Climate Change Conference in Glasgow: mitigation of the causes of climate change, via emissions cuts; adaptation to its effects; and carbon dioxide removal, via both nature-based solutions and negative-emissions technologies.
Given the quickening pace and growing magnitude of the climate emergency, however, the world must also consider the feasibility and wisdom of adding a fourth arrow to this quiver: solar climate intervention, or SCI. Also known as solar radiation management, solar geoengineering or albedo modification, SCI refers to large-scale efforts to counteract the warming effect caused by accumulating greenhouse gas emissions, particularly by enhancing Earth’s reflectiveness through experimental techniques such as dispersing aerosols in the stratosphere or brightening marine clouds with salt crystals.
SCI has been proposed as a relatively inexpensive and fast-acting strategy to slow or even reverse climate change and its consequences while humanity makes progress on emissions reductions and carbon-dioxide removal. It will surely become more tempting as the world blows well past the Paris Agreement targets and planetary temperatures rise. At the same time, considerable scientific uncertainty surrounds the potential efficacy and impacts of such interventions, and there are few international rules governing the intentional manipulation of the Earth’s climate system.