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Geoengineering technologies used to cool the planet are conventionally organized into two main categories:
solar radiation management (SRM) – reflecting incoming sunlight back to space - and
carbon dioxide removal (CDR) – taking carbon dioxide out of the atmosphere.
NOAC (and this website) focuses its efforts on SRM techniques.
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The main function of solar radiation management (also referred to as "albedo modification")
is to increase the Earth's reflectivity ("albedo") so that more of the sun's energy is reflected back into space,
thus cooling the planet. The cooling is needed in order to avoid the cascading tipping points that will occur in the next decade or so if there is no intervention in climate system.
Examples of albedo modification include: |
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Increasing the reflectivity of clouds This can be done by
spraying seawater into low-lying marine cloud formations thereby whitening clouds and increasing their albedo
(usually to as "marine cloud brightening" or MCB)
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Whitening land and water surfaces to reduce solar radiation absorption.
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| • | Injecting particles into the upper atmosphere (often referred to as "stratospheric aerosol injection" or SAI). |
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Albedo modification technologies would be relatively fast-acting (yielding results in years to decades), comparatively inexpensive
(costing as little as $1 to $10 billion per year), and extremely high-leverage in their effects.
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Climate-modeling studies show that albedo modification is surprisingly effective, offsetting many but not all climate risks associated with global warming.
Indeed, the results of these studies, combined with observations of the effects of natural perturbations of the atmosphere such as volcanic eruptions,
suggest there is little doubt that albedo modification could be used to limit global mean temperature rise to less than 2°C.
These attributes make albedo modification a potentially hugely disruptive technology on a truly global scale.
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