Geoengineering and Climate Change: Basics Explained
Geoengineering refers to a set of emerging technologies that could manipulate the environment and partially offset some of the impacts of climate change; geoengineering is conventionally split into two broad categories:
The first is carbon geoengineering, often also called carbon dioxide removal (cdr); the other is solar geoengineering
Carbon geoengineering seeks to remove carbon dioxide from the atmosphere, which would address the root cause of climate change — the accumulation of carbon dioxide in the atmosphere. In the chain from emissions to concentrations to temperatures to impacts, it breaks the link from emissions to concentrations.
Solar geoengineering refers to proposed approaches to cool the Earth by reflecting solar radiation back to space—also referred to as solar radiation management—describes a set of proposed approaches to reflect sunlight to rapidly cool the Earth.
Researchers are considering two main approaches. The first—stratospheric aerosol injection, or SAI—would involve injecting tiny reflecting particles, known as aerosols, into the upper atmosphere to cool the planet. The second—marine cloud brightening, or MCB—would use sea salt to stimulate cloud formation over the ocean, which would also help reflect sunlight in the region.
In effect, SAI simulates what happens during large volcanic eruptions, when volcanoes emit small particles into the upper atmosphere (called the stratosphere). These particles reflect sunlight and lead to cooling for as long as they remain in the stratosphere, which may be up to a few years after injection. By injecting sulfate or other aerosol particles into the stratosphere, SAI would mimic the cooling effect of a large volcanic eruption’s effect of lower global temperatures.
If ever deployed, SAI would have global impacts, reducing temperatures and altering precipitation patterns across the planet.
MCB would involve spraying sea salt into low-lying marine clouds to enhance their brightness and reflectivity in order to increase regional-scale cooling
But the deployment of this technology will become an excuse to slow emissions reductions and stop moving toward a low-carbon economy-the root cause of climate change: rising emissions of heat-trapping gases from burning fossil fuels—or some of the resulting impacts, such as ocean acidification.
Solar geoengineering, in particular, could not be a replacement for reducing emissions (mitigation) or coping with a changing climate (adaptation); yet, it could supplement these efforts.
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