When politicians and journalists declare that the science of
global warming is settled, they show a regrettable ignorance about
how science works. We were treated to another dose of it recently
when the experts of the Intergovernmental Panel on Climate Change
issued the Summary for Policymakers that puts the political spin
on an unfinished scientific dossier on climate change due for
publication in a few months’ time. They declared that most
of the rise in temperatures since the mid-20th century is very
likely due to man-made greenhouse gases.
The small print explains “very likely” as meaning
that the experts who made the judgment felt 90% sure about it.
Older readers may recall a press conference at Harwell in 1958
when Sir John Cockcroft, Britain’s top nuclear physicist,
said he was 90% certain that his lads had achieved controlled
nuclear fusion. It turned out that he was wrong. More positively,
a 10% uncertainty in any theory is a wide open breach for any
latterday Galileo or Einstein to storm through with a better idea.
That is how science really works.
Twenty years ago, climate research became politicised in favour
of one particular hypothesis, which redefined the subject as the
study of the effect of greenhouse gases. As a result, the rebellious
spirits essential for innovative and trustworthy science are greeted
with impediments to their research careers. And while the media
usually find mavericks at least entertaining, in this case they
often imagine that anyone who doubts the hypothesis of man-made
global warming must be in the pay of the oil companies. As a result,
some key discoveries in climate research go almost unreported.
Enthusiasm for the global-warming scare also ensures that heatwaves
make headlines, while contrary symptoms, such as this winter’s
billion-dollar loss of Californian crops to unusual frost, are
relegated to the business pages. The early arrival of migrant
birds in spring provides colourful evidence for a recent warming
of the northern lands. But did anyone tell you that in east Antarctica
the Adélie penguins and Cape petrels are turning up at
their spring nesting sites around nine days later than they did
50 years ago? While sea-ice has diminished in the Arctic since
1978, it has grown by 8% in the Southern Ocean.
So one awkward question you can ask, when you’re forking
out those extra taxes for climate change, is “Why is east
Antarctica getting colder?” It makes no sense at all if
carbon dioxide is driving global warming. While you’re at
it, you might inquire whether Gordon Brown will give you a refund
if it’s confirmed that global warming has stopped. The best
measurements of global air temperatures come from American weather
satellites, and they show wobbles but no overall change since
1999.
That levelling off is just what is expected by the chief rival
hypothesis, which says that the sun drives climate changes more
emphatically than greenhouse gases do. After becoming much more
active during the 20th century, the sun now stands at a high but
roughly level state of activity. Solar physicists warn of possible
global cooling, should the sun revert to the lazier mood it was
in during the Little Ice Age 300 years ago.
Climate history and related archeology give solid support to
the solar hypothesis. The 20th-century episode, or Modern Warming,
was just the latest in a long string of similar events produced
by a hyperactive sun, of which the last was the Medieval Warming.
The Chinese population doubled then, while in Europe the Vikings
and cathedral-builders prospered. Fascinating relics of earlier
episodes come from the Swiss Alps, with the rediscovery in 2003
of a long-forgotten pass used intermittently whenever the world
was warm.
What does the Intergovernmental Panel do with such emphatic evidence
for an alternation of warm and cold periods, linked to solar activity
and going on long before human industry was a possible factor?
Less than nothing. The 2007 Summary for Policymakers boasts of
cutting in half a very small contribution by the sun to climate
change conceded in a 2001 report.
Disdain for the sun goes with a failure by the self-appointed
greenhouse experts to keep up with inconvenient discoveries about
how the solar variations control the climate. The sun’s
brightness may change too little to account for the big swings
in the climate. But more than 10 years have passed since Henrik
Svensmark in Copenhagen first pointed out a much more powerful
mechanism.
He saw from compilations of weather satellite data that cloudiness
varies according to how many atomic particles are coming in from
exploded stars. More cosmic rays, more clouds. The sun’s
magnetic field bats away many of the cosmic rays, and its intensification
during the 20th century meant fewer cosmic rays, fewer clouds,
and a warmer world. On the other hand the Little Ice Age was chilly
because the lazy sun let in more cosmic rays, leaving the world
cloudier and gloomier.
The only trouble with Svensmark’s idea — apart from
its being politically incorrect — was that meteorologists
denied that cosmic rays could be involved in cloud formation.
After long delays in scraping together the funds for an experiment,
Svensmark and his small team at the Danish National Space Center
hit the jackpot in the summer of 2005.
In a box of air in the basement, they were able to show that
electrons set free by cosmic rays coming through the ceiling stitched
together droplets of sulphuric acid and water. These are the building
blocks for cloud condensation. But journal after journal declined
to publish their report; the discovery finally appeared in the
Proceedings of the Royal Society late last year.
Thanks to having written The Manic Sun, a book about Svensmark’s
initial discovery published in 1997, I have been privileged to
be on the inside track for reporting his struggles and successes
since then. The outcome is a second book, The Chilling Stars,
co-authored by the two of us and published next week by Icon books.
We are not exaggerating, we believe, when we subtitle it “A
new theory of climate change”.
Where does all that leave the impact of greenhouse gases? Their
effects are likely to be a good deal less than advertised, but
nobody can really say until the implications of the new theory
of climate change are more fully worked out.
The reappraisal starts with Antarctica, where those contradictory
temperature trends are directly predicted by Svensmark’s
scenario, because the snow there is whiter than the cloud-tops.
Meanwhile humility in face of Nature’s marvels seems more
appropriate than arrogant assertions that we can forecast and
even control a climate ruled by the sun and the stars.
The Chilling Stars is published by Icon. It is available for
£9.89 including postage from The Sunday Times Books First
on 0870 165 8585
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