40 | New Scientist | 31 August 2019How to be Superhuman
Rowan Hooper is speaking at New Scientist Live
about people at the peaks of human potential
newscientistlive.com10 million windmills across the entire Arctic to
refreeze it, at a cost of $500 billion. That is a
huge sum, but just a fraction of the estimated
$67 trillion economic impact of Arctic warming
if we don’t act. Bitz has evaluated Desch’s idea
in a paper currently submitted for publication.
“The physics can work,” she says. “The basic
principles make sense. To me that’s
promising.” But so far, Desch only has a
prototype windmill that works in the lab.
For a true test, field trials are essential.
The second proposal for geoengineering
the Arctic has had some success outside the
lab. It involves covering the ice with shiny,
white beads. The idea is that these microbeads
increase the reflectiveness, or albedo, of thin,
young ice, so protecting it from the sun. The
leading advocate is Leslie Field, an engineer at
Stanford University in California, who also
runs Ice911 Research, a non-profit organisation
exploring methods of restoring Arctic ice,
mainly using hollow silica microspheres.
These bright, non-toxic beads are chemically
and physically similar to sand but smaller,
more like powder, with a diameter of about
65 micrometres (0.065 millimetres).
Field and her colleagues have tested the idea,
most notably on about 4200 square metres of
North Meadow Lake in Alaska. They have
shown that the microspheres increase albedo
by around 20 per cent and slow the ice melting.
To cover 25,000 square kilometres of the Arctic
with the stuff would cost about $300 million for
the materials alone, says Field. This represents
just 0.7 per cent of summer ice coverage at its
lowest extent on record: 3.4 million square
kilometres in 2012. Yet many questions remain,
not least whether it works on sea ice – so far it
has only been tested on frozen lakes. And what
happens to the beads when ice melts? Some
sink and are incorporated into the mud on the
lake floor, says Field.
There are, however, concerns about the
biological hazards of this approach. Bitz says
she is worried about the ecological impact of
adding millions of tonnes of silica to the Arctic.
“For me this raises a red flag,” she says.
Ken Caldeira, who researches
geoengineering at the Carnegie Institution for
Science in California, has doubts about the
workability of modifying the surface of the
ice – whether by the methods proposed by
Field or Desch – and about whether this could
be an effective tool against climate change.
“I am highly sceptical that this approach will
prove feasible and desirable at scales required
to be climatically substantial,” he says.
For Bitz, Wadhams and several other climate
scientists who spoke to New Scientist, the mostLast ice?
About one-third of the Arctic’s summer
sea ice has disappeared over the past
40 years. This is an area of approximately
2.4 million square kilometres – roughly
the size of AlgeriaSept 1979
7.1 million km^2
Sept 2018
4.7 million km^2Algeria
2,382,000 km^2“ Arctic sea ice may be restored
by brightening ocean
stratocumulus clouds”
Reflective microspheres
(below left) are being used to
preserve winter ice in North
American lakes (right)AL
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