“Cooling credits” are not a viable climate solution

Abstract

As the world struggles to limit warming to 1.5 or 2 °C below pre-industrial temperatures, research into solar climate interventions that could temporarily offset some amount of greenhouse gas-driven global warming by reflecting more sunlight back out to space has gained prominence. These solar climate intervention techniques would aim to cool the Earth by injecting aerosols (tiny liquid or solid particles suspended in the atmosphere) into the upper atmosphere or into low-altitude marine clouds. In a new development, “cooling credits” are now being marketed that claim to offset a certain amount of greenhouse gas warming with aerosol-based cooling. The science of solar climate intervention is currently too uncertain and the quantification of effects insufficient for any such claims to be credible in the near term. More fundamentally, however, the environmental impacts of greenhouse gases and aerosols are too different for such credits to be an appropriate instrument for reducing climate risk even if scientific uncertainties were narrowed and robust monitoring systems put in place. While some form of commercial mechanism for solar climate intervention implementation, in the event it is used, is likely, “cooling credits” are unlikely to be a viable climate solution, either now or in the future.

Responses of Extreme Climates in South Asia under a G6sulfur Scenario of Climate Engineering

“…At the same time, with increasing injection rates in the 21st century, compared to the SSP585 scenario, SAI climate engineering would intensify the decrease in precipitation in southern Europe [7,8]. Such a reduction in both temperature and precipitation is mainly because the implementation of SAI climate engineering would alter temporal and spatial distributions of temperature change between day and night, between seasons, and between the tropics and the poles [9]. Jones et al [4], further, found that the implementation of SAI climate engineering would force an increasingly positive phase of the North Atlantic Oscillation (NAO) as the injection rate increased over the course of the 21st century, and cause the Quasi-Biennial Oscillation (QBO) to stall and become locked in a phase with permanent westerly winds in the lower stratosphere [7].…”