Methods · Stratospheric aerosol injection (SAI) · Marine cloud brightening (MCB) · Cirrus cloud thinning (CCT) · Reflective surfaces · Space-based methods.
Space-based geoengineering involves the use of space-based devices to reflect or block sunlight, thereby reducing the amount of solar energy reaching the Earth.
These include stratospheric aerosol injection (SAI), marine cloud brightening, and surface albedo modification. While SRM could temporarily
**Solar Radiation Modification (SRM) refers to deliberate, large-scale actions intended to decrease global average surface temperatures by increasing the reflection of sunlight away from the Earth.** Proposed SRM methods involve the use of aerosols (small particles) or other materials to increase the reflectivity of the atmosphere, clouds, or Earth’s surface. **Long-term protection of Earth’s climate and oceans requires substantial reductions in emissions and atmospheric concentrations of CO2 and other GHGs. SRM is not considered a substitute for climate mitigation efforts, which include decarbonization and GHG emission cuts.** SRM research is being conducted as a response to growing concerns that the pace of CO2 emissions reductions and CDR technology development is not sufficient to avoid severe impacts of climate change in the next decades. **Many of the processes most important for understanding SRM approaches—such as those that control the formation of clouds and aerosols—are among the most uncertain components of the climate system.** Climate models differ in simulating large-scale aerosol climate effects, including on surface temperatures, due to variations in how aerosol processes, atmospheric transport and mixing, and physics are represented.
For example, geoengineering includes the removal of carbon dioxide from the atmosphere (also called Carbon Dioxide Removal – CDR) through methods such as direct air capture and storage, ocean iron fertilization, or ocean alkalinity enhancement. These activities are referred to as **Solar Geoengineering** or **Solar Radiation Modification (SRM).** Most proposed solar radiation modification techniques involve adding material to the atmosphere to increase the amount of incoming sunlight reflected back to space. Marine solar radiation management (mSRM) techniques, on the other hand, involve adding materials to ocean waters, sea ice, or the lower atmosphere to increase the amount of solar radiation reflected at or near the ocean's surface to limit surface warming or sea ice melt. * *Marine Cloud Brightening (MCB)* – adding particles, such as sea spray, to the lower atmosphere (near the surface) to increase the reflectivity of clouds over the ocean. Another subset of geoengineering activities intends to cool the Earth by intentionally modifying the concentration of certain gases in the atmosphere, including carbon dioxide.
by I Szapudi · 2023 · Cited by 16 — Two strategies proposed for SRM involve adding dust or chemicals to the Earth's atmosphere to increase the reflected fraction of sunlight (6–8)
In this chapter, we briefly review what is known about proposed solar radiation management (SRM) approaches and related governance and ethical issues and conclude with a discussion of the research needed to better understand SRM. For use of SRM as a potential “backstop option” in the case of an emerging “climate emergency,” improved observations and understanding of climate system thresholds, reversibility, and abrupt changes (see Chapter 6)—for example, observations to let us know when an ice sheet or methane hydrate field may become unstable (e.g., Khvorostyanov et al., 2008; Shakhova et al., 2010)—could inform societal debate and decision making about needs for deployment of a climate intervention system. There is, however, additional research that would be needed to support full evaluation of SRM approaches (just as there is with other options for limiting the magnitude of future climate change), including a variety of social, ecological, and physical sciences (see Chapter 4).
The Harvard Solar Geoengineering Research Program (SGRP) aims to reduce uncertainties surrounding solar geoengineering; generate critical science, technology, and policy insights; and help inform the public debate surrounding this controversial idea. Recognizing that solar geoengineering could not be a replacement for reducing emissions or adapting to climate impacts, SGRP draws on Harvard’s research capabilities and global convening power to provide the knowledge necessary in considering solar geoengineering as a supplement to broader mitigation and adaptation efforts. The Harvard Solar Geoengineering Research Program (SGRP) aims to reduce uncertainties surrounding solar geoengineering; generate critical science, technology, and policy insights; and help inform the public debate surrounding this controversial idea. Recognizing that solar geoengineering could not be a replacement for reducing emissions or adapting to climate impacts, SGRP draws on Harvard’s research capabilities and global convening power to provide the knowledge necessary in considering solar geoengineering as a supplement to broader mitigation and adaptation efforts. * In 1980, Professor Tom Schelling chaired a National Academy of Sciences committee whose report, *Changing Climate*, addressed the potential for solar geoengineering to counter global warming.