Page 250 - James Rodger Fleming - Fixing the sky

In this vein, atmospheric scientist Alan Robock, a leader in modeling efforts
to evaluate climate-engineering schemes, recently wrote,

The reasons why geoengineering may be a bad idea are manifold, though a mod-
erate investment in theoretical geoengineering research might help scientists to
determine whether or not it is a bad idea. Small-scale deployments are out of the
question until we are sure that known adverse consequences can be avoided. Then
there are the [Donald Rumsfeld–like] multiple unknown unknowns that argue
against ever undertaking a large-scale deployment. 23

His list of twenty reasons (subsequently pared down to seventeen) why geoen-
gineering (especially solar radiation attenuation by sulfates) may be a bad idea
includes:

(1) Potentially devastating effects on regional climate, including drought in Africa
and Asia, (2) Accelerated stratospheric ozone depletion, (3) Unknown envi-
ronmental impacts of implementation, (4) Rapid warming if deployment ever
stops, (5) Inability to reverse the effects quickly, (6) Continued ocean acidifica-
tion, (7) Whitening of the sky, with no more blue skies, but nice sunsets, (8) The
end of terrestrial optical astronomy, (9) Greatly reduced direct beam solar power,
(10) Human error, (11) The moral hazard of undermining emissions mitigation,
(12) Commercialization of the technology, (13) Militarization of the technology,
(14) Conflicts with current treaties, (15) Who controls the thermostat? (16) Who
has the moral right to do this? (17) Unexpected consequences. 24

Some of these results (1–5) are derived from general circulation model simula-
tions and others (6–9) from back-of-the-envelope calculations; most, however,
(10–17) stem from historical, ethical, legal, and social considerations. Robock
admits that geoengineering would have certain benefits, including cooling the
planet, possibly reducing or reversing sea ice and ice sheet melting and sea level
rise, and increasing plant productivity and thus the terrestrial carbon sink.
Most enthusiasts for solar radiation management have overlooked, however,
its “dark” side: the scattering of starlight as well as sunlight, which would further
degrade seeing conditions for both ground-based optical astronomy and general
night sky gazing. A recent article by astronomers Christian Luginbuhl, Con-
stance Walker, and Richard Wainscoat discusses the rapid growth of light pollu-
tion from ground-based sources but does not consider aerosol scattering effects
25
that reduce nighttime seeing. Imagine the outcry from professional astrono-
mers and the general public if the geoengineers pollute the stratosphere with a

tHe Climate enGineerS | 233