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Thursday, November 26, 2015

Writing on the wall - Understanding global warming is fine, the point is to stop it

The November 27th New Scientist Editorial
NEW SCIENTIST 
issue: 2214, volume: 164, year: 1999, 
pages: 5 - 5

Writing on the wall
Understanding global warming is fine, the point is to stop it

CONSENSUS is a dangerous thing in science.
The notion that researchers can ever prove their
theories is long gone--they can only wait for
others to knock them down. This means that to
be healthy, science needs an opposition, and
when politicians ask scientists to reach a common
view, it pays to be wary.

For a decade now, the UN's Intergovernmental
Panel on Climate Change (IPCC) has had the task
of moulding adversarial science into a consensual
form. Its third assessment of climate change
science, now circulating in draft form for
comment, is an impressive example of the art,
dealing as it does with a controversial matter of
utmost importance to the whole world.

As we reported last week, the IPCC says there is
now little room for doubt that global warming in
the past 25 years is our fault. With the help of
increasingly successful climate models, it lays out
our likely future in awful detail. We have
probably already signed death warrants for
several low-lying Pacific islands, casualties of
rising sea levels. And if we let concentrations of
greenhouse gases increase more than 50 per
cent above present levels--which could happen
by the middle of next century--the Amazon
rainforest will simply shrivel up and die.

Of course, committees charged with reaching a
consensus may gloss over contentious details,
and simplified models of the real world still leave
plenty of room for improvement. We know little
about how clouds created by extra evaporation in
a warmer world will influence temperature. And
there is an alarming fuzziness about atmospheric
mechanisms that could turn small changes in
solar radiation into large temperature swings
here on Earth. But the IPCC's draft report is
honest on these points, stressing that uncertainty
should be a cause for more concern, not an
excuse for delaying action.

Among other uncertainties, it asks whether
melting Arctic ice will dilute the waters of the
North Atlantic, shutting down a massive "pump"
that is driven by salty waters sinking to the ocean
floor. If this happens, it would reduce the ocean's
uptake of carbon dioxide and accelerate global
warming. Perversely, it would also cut off the
currents that warm Western Europe, so London,
Paris and Madrid would shiver while the rest of
the world sweltered. In this issue we report the
first evidence from the Atlantic that this
hypothetical event may be starting to happen.

In the few years since the world woke up to the
threat of climate change, science has made
impressive strides in describing how Earth's
life-support systems work. At a meeting in Bonn
earlier this month, where more than 160
governments discussed targets for cutting
emissions of greenhouse gases, NOT ONE VOICED
DOUBTS ABOUT THE SCIENTIFIC UNDERPINNINGS OF THEIR
DELIBERATIONS.

But can you have too much of consensus? The
IPCC must guard against this. It makes a point of
drawing sometimes hostile sceptics into its
deliberations. The latest report, for instance,
includes major contributions from researchers
studying the potential impact of changes in solar
radiation on our temperature. It has also set up a
group specifically to search for scientific surprises
that could upset its calculations.

Dangerous it may be, but the IPCC has turned
consensus into a virtue. It is now time for
governments to show that they can act as one to
halt the coming nightmare.

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