The article “Engineering a cooler
Earth” ( SN: 6/5/10, p. 16) was incredibly irritating. The solution to global
warming is not technology of the
type presented, but population and
pollution control. You need to start
talking about that. The longer we see
the problem in technical terms, the
less likely we are to even talk about
the real solutions. (How many articles
have you had recently discussing
limiting population — that’s science,
isn’t it?) Suppose we dump a bunch of
chemicals in the biosphere and it cuts
global temperatures a bit or holds them
steady. Is that the kind of outcome we
want so we can dump ever more CO2
into the atmosphere and add a billion
or two more people?
Bill Amborn, West Linn, Ore.
Your article on geoengineering raised,
but did not fully explore, the crucially
important question of the impact of
the cloud-brightening scheme on rain-
fall over land. Three studies have been
made, by three separate groups, using
three different and well-regarded mod-
els. One by Jones et al (2009) seeded
a small fraction of suitable maritime
clouds and reported significant reduc-
tions of rainfall over northern South
America. Another, Rasch et al (2009),
seeded an intermediate fraction, found
no rainfall reduction in this area, and no
significant rainfall reduction over land.
A third, to be published by Bala et al,
seeded all suitable clouds and found
no rainfall reduction anywhere over
land. They provided a plausible physi-
cal/meteorological explanation for this
result. No categoric statement can cur-
rently be made as to whether or not the
cloud-brightening scheme would reduce
rainfall significantly anywhere over land.
John Latham, National Center for
Atmospheric Research, Boulder, Colo.
Stephen Salter, University of Edinburgh,
ET, phone where?
It seems from your article “Can you
hear me now?” (SN: 4/24/10, p. 22) that
most searches for ET communications
have assumed that we were looking for
a deliberate signal — that we assumed
ET was trying to phone us. But seriously, why should he? It would be horribly foolish to assume that ET politics
resembled ours, but the allocation of
resources according to priorities is a
necessary preoccupation of life from
the single cell on up. Yelling into the
void by any of the methods described
would use power that would likely be
needed elsewhere. (Are we doing it on
purpose?) Only the searches for leakage
from ET power generation are likely to
turn up anything, and they will be difficult to sort out from natural causes.
Nancy Parker, Caldwell, Idaho
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