CLIMATE CHALLENGESTo Reduce Growing Climate Dangers, the World Needs to Consider Sunlight Reflection

By Stewart M. Patrick

Published 29 April 2022

Nothing about the present climate crisis or its implications is natural. Perhaps how the world deals with a warming planet shouldn’t be either.

For too long, sunlight reflection has been the third rail of climate change politics, a relegation that has severely crippled its basic research and discussion in diplomatic circles. This situation, however, is starting to change as the devastating implications of a fast-warming planet become impossible to ignore. Today, the Council on Foreign Relations released a new Special Report on the topic: Reflecting Sunlight to Reduce Climate Risk: Priorities for Research and International CooperationIt calls on the United States to launch a robust sunlight reflection research program and spearhead international negotiations to advance multilateral scientific assessments of and collective decision-making regarding these novel techniques and their potential future implementation.

Sunlight reflection, also known as solar climate intervention (SCI) or solar geoengineering, would entail reflecting a tiny percentage of sunlight back into space to reduce the heating effects of solar radiation on greenhouse gases, thus limiting—and conceivably even reducing—the rise in global temperatures that would otherwise occur. The two simplest and most cost-effective means of doing so would be either dispersing aerosols in the stratosphere or spraying salt crystals from ocean-based platforms to brighten low-lying marine clouds.

While these interventions may sound radical, they have existing analogues. The first approach, for instance, would mimic the cooling effect of volcanic eruptions like that of Mount Pinatubo in the Philippines in 1991, which reduced global temperatures between 0.5 and 1.1°C over the next fifteen months.

Desperate times, moreover, may call for desperate measures. As the reports of the Intergovernmental Panel on Climate Change’s sixth assessment cycle make clear, the climate emergency is now. Unfortunately, the world’s current approaches to preventing catastrophic warming and muting its implications are failing. Just yesterday, the United Nations Office for Disaster Risk Reduction warned that climate change is putting humanity on course for a “spiral of self-destruction.” Thanks to unchecked global warming, once rare calamities like extreme heatwaves, prolonged droughts, violent storms, and catastrophic floods are becoming commonplace. The number of major disasters per year quadrupled from about ninety to one hundred during the period between 1970 and 2000 to about 400 in 2015. This number could increase to 560 (or 1.5 per day) by 2030.