A technique to cool the planet, in which particles are added to the atmosphere to reflect sunlight, would not require developing special aircraft.
Nevertheless, James Hansen, director of the Program on Climate Science, Awareness and Solutions at Columbia’s Climate School, who first warned Congress about climate change risks in 1988, and a group of over 60 scientists are calling for more research into solar geoengineering. Most research into solar geoengineering strategies is currently focused on stratospheric aerosol injection (SAI, also called solar radiation management or SRM) and marine cloud brightening; other strategies include cirrus cloud thinning and the use of mirrors or sunshades. According to Gernot Wagner, co-founder of Harvard’s Solar Geoengineering Research Program and currently a climate economist at Columbia, the most important and determinative modeling variables are how high up in the stratosphere and where specifically SAI is deployed. In 2011, David Keith, Harvard’s Solar Geoengineering Research Program co-founder who is now at the University of Chicago, and atmospheric scientist Ken Caldeira estimated that to reverse 10% of the warming caused by a doubling of CO2 levels compared to the pre-industrial era, several hundred thousand tons of sulfur dioxide would have to be injected annually over a decade.
A technique to cool the planet, in which particles are added to the atmosphere to reflect sunlight, would not require developing special aircraft but could be achieved using existing large planes, according to a new modelling study led by UCL researchers. Previously, most research has assumed that the technique, known as stratospheric aerosol injection, would be deployed in the tropics and so would require specially designed aircraft capable of flying at altitudes of 20km or more to inject the particles. For the new study, published in the journal *Earth’s Future*, scientists ran simulations of different aerosol injection strategies and concluded that adding particles 13km above the polar regions could meaningfully cool the planet, albeit much less effectively than at higher altitudes closer to the equator. The strategy is not a quick fix – any stratospheric aerosol injection would need to be introduced gradually, and reduced gradually, to avoid catastrophic impacts from sudden warming or cooling.
Researchers at the University of California, Santa Barbara examined two methods designed to reduce the amount of sunlight reaching Earth’s surface: cloud seeding over the eastern Pacific Ocean and the release of aerosols into the stratosphere. ENSO is a recurring climate pattern that develops every 2 to 7 years and shifts the distribution of warm water across the tropical Pacific Ocean. “It’s hard to get ENSO to change by that much that quickly,” said Associate Professor Samantha Stevenson, a co-author of the study and advisor to Xing and Pfleger. Because of this broader distribution, SAI creates a more uniform cooling effect and is less likely to disrupt regional climate systems like ENSO. “There’s nothing that compares to the speed with which ENSO would change in these MCB experiments,” Stevenson said. “Two interventions can get to the same warming target globally and have extremely different regional climate impacts,” Stevenson said. #### Reducing Climate Change Risks With the Right Dose of Geoengineering.
This episode of *Weathered* explores solar geoengineering, a controversial method of injecting sulfate aerosols into the stratosphere to create a global cooling effect. Science Earth and Space Science Earth's Atmosphere Global and Regional Climate Change Atmospheric Composition Global Warming Mitigation and Adaptation Strategies Structure of the Atmosphere English Language Arts and Literacy Reading in Science & Technical Subjects Speaking and Listening Comprehension and Collaboration Integration of Knowledge and Ideas Argument and Reasoning Point of View, Reasoning, Evidence, and Rhetoric Engineering & Technology Engineering Design and Practices Designing Solutions Personal and Professional Ethics Safety, Health, and Welfare of the Public. 4. After watching the video, do you lean more toward using or not using geoengineering as a tool to address the effects of climate change, and why? * **Is injecting aerosols into Earth's atmosphere a good solution for reducing the effects of global climate change?**. 5. Which components of the global climate system does Dr. Aarti Gupta mention could be affected by large scale injection of aerosols into the atmosphere?
By substituting their cooling effect by deploying stratospheric aerosol geoengineering we can have cleaner air without the extra warming.
Chicago Curriculum on Climate and Sustainable Growth. For some of us in the world of climate science, this raises a thorny question: Should we explore replacing the inadvertent cooling effects of sulfur with a cleaner, deliberate version? But if policymakers decide that it is needed, a more modest approach would be to run a small, carefully scaled program that slightly increases the upper atmosphere’s reflectivity to compensate for the loss of cooling as sulfur pollution is eliminated. It would be to keep the total cooling from sulfur roughly constant for a period of time, reducing near-term climate risk while decarbonization efforts continue. As world leaders gather in New York for the U.N. General Assembly and Climate Week, any discussions of sunlight reflection should have a clear, enforceable commitment to never cool the Earth more than today’s current sulfur emissions do. Chicago Curriculum on Climate and Sustainable Growth.
This paper analyzes the potential to mitigate global warming using radiative cooling (RC) surfaces on a large scale.