.
My recent
Times column argued that the alleged healing
of the ozone layer is exaggerated, but so was the impact of the
ozone hole over Antarctica:
The ozone layer is healing. Or so said the news
last week. Thanks to a treaty signed in Montreal in 1989 to get rid
of refrigerant chemicals called chlorofluorocarbons (CFCs), the
planet’s stratospheric sunscreen has at last begun thickening
again. Planetary disaster has been averted by politics.
For reasons I will explain, this news deserves to be taken with
a large pinch of salt. You do not have to dig far to find evidence
that the ozone hole was never nearly as dangerous as some people
said, that it is not necessarily healing yet and that it might not
have been caused mainly by CFCs anyway.
The timing of the announcement was plainly political: it came on
the 25th anniversary of the treaty, and just before a big United
Nations climate conference in New York, the aim of which is to push
for a climate treaty modelled on the ozone one.
Here’s what was actually announced last week, in the words of a
Nasa scientist, Paul Newman: “From 2000 to 2013, ozone levels
climbed 4 per cent in the key mid-northern latitudes.” That’s a
pretty small change and it is in the wrong place. The ozone
thinning that worried everybody in the 1980s was over
Antarctica.
Over northern latitudes, ozone concentration has been falling by
about 4 per cent each March before recovering. Over Antarctica,
since 1980, the ozone concentration has fallen by
40 or 50 per cent each September before the sun rebuilds
it.
So what’s happening to the Antarctic ozone hole? Thanks to a
diligent blogger named Anthony Watts, I came across a press release
also from Nasa about nine months ago, which said: “
Two new studies show that signs of recovery are not yet
present, and that temperature and winds are still driving any
annual changes in ozone hole size.”
As recently as 2006, Nasa announced, quoting Paul Newman again,
that the Antarctic ozone hole that year was “the largest ever
recorded”. The following year a paper in Nature
magazine from Markus Rex, a German scientist, presented new
evidence that suggested CFCs may be responsible for less than 40
per cent of ozone destruction anyway. Besides, nobody knows for
sure how big the ozone hole was each spring before CFCs were
invented. All we know is that it varies from year to year.
How much damage did the ozone hole ever threaten to do anyway?
It is fascinating to go back and read what the usual
hyperventilating eco-exaggerators said about ozone thinning in the
1980s. As a result of the extra ultraviolet light coming through
the Antarctic ozone hole, southernmost parts of Patagonia and New
Zealand see about 12 per cent more UV light than expected. This
means that the weak September sunshine, though it feels much the
same, has the power to cause sunburn more like that of latitudes a
few hundred miles north. Hardly Armageddon.
The New York Times reported “an increase
in Twilight Zone-type reports of sheep and
rabbits with cataracts” in southern Chile. Not to be outdone, Al
Gore wrote that “hunters now report finding blind rabbits;
fisherman catch blind salmon”. Zoologists briefly blamed the near
extinction of many amphibian species on thin ozone.
Melanoma in people was also said to be on the rise as a
result.
This was nonsense. Frogs were dying out because of a fungal
disease spread from Africa — nothing to do with ozone. Rabbits and
fish blinded by a little extra sunlight proved to be as mythical as
unicorns. An eye disease in Chilean sheep was happening outside the
ozone-depleted zone and was caused by an infection called pinkeye —
nothing to do with UV light. And melanoma incidence in people
actually levelled out during the period when the
ozone got thinner.
Then remember that the ozone hole appears when the sky is dark
all day, and over an uninhabited continent. Even if it persists
into the Antarctic spring and spills north briefly, the hole allows
50 times less ultraviolet light through than would hit your skin at
the equator at sea level (let alone at a high altitude) in the
tropics. So it would be bonkers to worry about UV as you sailed
round Cape Horn in spring, say, but not when you stopped at the
Galapagos: the skin cancer risk is 50 times higher in the latter
place.
This kind of eco-exaggeration has been going on for 50 years. In
the 1960s Rachel Carson said there was an epidemic of childhood
cancer caused by DDT; it was not true — DDT had environmental
effects but did not cause human cancers.
In the 1970s the Sahara desert was said be advancing a mile a
year; it was not true — the region south of the Sahara has grown
markedly greener and more thickly vegetated in recent decades.
In the 1980s acid rain was said to be devastating European
forests; not true — any local declines in woodland were caused by
pests or local pollution, not by the sulphates and nitrates in
rain, which may have contributed to an actual increase in the
overall growth rate of European forests during the decade.
In the 1990s sperm counts were said to be plummeting thanks to
pollution with man-made “endocrine disruptor” chemicals; not true —
there was no fall in sperm counts.
In the 2000s the Gulf Stream was said to be failing and
hurricanes were said to be getting more numerous and worse, thanks
to global warming; neither was true, except in a Hollywood
studio.
The motive for last week’s announcement was to nudge world
leaders towards a treaty on climate change by reminding them of how
well the ozone treaty worked. But getting the world to agree to
cease production of one rare class of chemical, for which
substitutes existed, and which only a few companies mainly in rich
countries manufactured, was a very different proposition from
setting out to decarbonise the whole economy, when each of us
depends on burning carbon (and hydrogen) for almost every product,
service, meal, comfort and journey in our lives.
The true lesson of the ozone story is that taking precautionary
action on the basis of dubious evidence and exaggerated claims
might be all right if the action does relatively little economic
harm.
However, loading the entire world economy with costly energy,
and new environmental risks based on exaggerated claims about what
might in future happen to the climate makes less sense."
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