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Page 59
(Table 6.1 continued on page
58)
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Sunlight Screening
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Space Mirrors
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Place 50,000 100-km2 mirrors in the earth's orbit to
reflect incoming sunlight.
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Stratospheric Dustc
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Use guns or balloons to maintain a dust cloud in
the stratosphere to increase the sunlight reflection.
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Stratospheric Bubbles
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Place billions of aluminized, hydrogen-filled
balloons in the stratosphere to provide a reflective screen.
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Low Stratospheric Dustc
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Use aircraft to maintain a cloud of dust in the
low stratosphere to reflect sunlight.
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Low Stratospheric Sootc
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Decrease efficiency of burning in engines of
aircraft flying in the low stratosphere to maintain a thin cloud of
soot to intercept sunlight.
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Cloud Stimulationc
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Burn sulfur in ships or power plants to form
sulfate aerosol in order to stimulate additional low marine clouds
to reflect sunlight.
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Ocean Biomass Stimulation
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Place iron in the oceans to stimulate generation
of CO2-absorbing phytoplankton.
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Atmospheric CFC Removal
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Use lasers to break up CFCs in the atmosphere.
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a1 quad =
1 quadrillion Btu = 1015 Btu.
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bCorporate
average fuel economy.
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cThese
options cause or alter chemical reactions in the atmosphere and
should not be implemented without careful assessment of their
direct and indirect consequences.
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options, including space mirrors and removal of CFCs from the
atmosphere, are not included among those recommended for further
investigation in Chapter 9.
Geoengineering options appear technically feasible in terms of
cooling effects and costs on the basis of currently available
preliminary information. But considerably more study and research
will be necessary to evaluate their potential side effects,
including the chemical reactions that particles introduced into the
atmosphere might cause or alter. The data presented in Table 6.3
were developed during the course of the study and represent iniial
estimates. These or other options may, with additional
investigation, research, and development, provide the ability to
change atmospheric concentrations of greenhouse gases or the
radiative forcing of the planet.
Geoengineering options have the potential to affect greenhouse
warming on a substantial scale. However, precisely because they
might do so, and because the climate system and its chemistry are
poorly understood, these options must
