Science News - July 17, 2010

Engineering irritation 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,
Scotland

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

Send communications to: Editor, Science News, 1719 N Street, NW, Washington, D.C. 20036 or editors@sciencenews.org. Letters subject to editing.

Cyprus & Malta • Ethiopia • American Southwest
Iran • Oman • Maya World • Cambodia & Laos • China
Easter Island • Syria • Turkey • Egypt • England
Italy • India • Jordan • the Crusades • Scotland • Peru
Creating unique journeys
led by renowned scholars since 1983
JOURney into the
heart of History

www.aerosleeper.com Never Travel Without It!

2 for 1 9. 9 5

Travel
Widget
SLEEP
ON
PLANES

New
• Gently holds your head in
position.

Marketplace

1-800-552-4575 • www.farhorizons.com

New book profiles 20+ of the planet’s most active volcanoes and features: news; science; stats; maps; photos; alert status.

MAGAZINE OF THE SOCIE T Y FOR SCIENCE & THE PUBLIC
Save time, save
money and give
the magazine that
covers science
in a biweekly,
user-friendly
format. www.sciencenews.org/gift