WE KNOW all too well that the way we use a technology ultimately decides
whether it will be a blessing or a curse. Genetic testing, for example, should
be great for helping people to stave off disease, yet it could also stop them
getting jobs and insurance. The really tricky cases, though, are the
technologies that creep round the back and bite you when you least expect
it.
There鈥檚 a long list of nasty surprises. We thought the insecticide DDT and
chemicals such as PCBs were revolutionary, until we discovered their darker
sides. They cropped up in humans and whales living in the high Arctic, half a
world away from the nearest malarial mosquito and thousands of miles from
industrial centres. CFCs were terrific for keeping food cold, but turned out to
have a chilling effect on the ozone layer.
We鈥檝e been caught out so many times before, it鈥檚 worth taking a look over our
shoulder to check what surprises might still be lurking there to take a bite.
One prime candidate is the hydroxyl radical, a simple, highly reactive
combination of oxygen and hydrogen. This molecule plays a pivotal role in two of
humanity鈥檚 dumbest products鈥攁tmospheric pollution and climate change.
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Researchers have just reported that increasing emissions of nitrogen oxides
could reduce global warming, which seems perverse since some nitrogen oxides are
greenhouse gases while others create ozone, which is another
(see 鈥淗anging in the air鈥�). But
NOx emissions also create hydroxyl, which removes gases such as methane
from the air鈥攁nd methane is a far more potent greenhouse gas than
NOx. But now comes the tricky part鈥攎ix in some carbon monoxide,
and it will lap up hydroxyl like a sponge. Although carbon monoxide is pretty
insignificant as a greenhouse gas, it becomes the villain of the piece because
it stops hydroxyl cleaning up methane.
What this tells us is that atmospheric chemistry is a lot more complex than
it looks. Climate scientists must know a gas鈥檚 relationship with hydroxyl to
gauge its full contribution to global warming. Secondly, it implies that our
best efforts to reduce pollution could come back to haunt us. By continuing to
cut NOx emissions while ignoring carbon monoxide, we could run short of
hydroxyl, which would increase global warming.
And that鈥檚 not all. Hydroxyl purges the atmosphere of other pollutants and is
intimately connected with a third embarrassing human endeavour鈥攄estruction
of the ozone layer. Read the
feature on p 8 of the Global Environment Supplement
with this issue for the effects of this calamity.
We humans have never for a minute doubted our ability to solve environmental
problems. But, for most of our history, those problems have been localised. We
could always start over somewhere else. But that option has gone. The unexpected
consequences of today鈥檚 technologies can affect the whole world. We ignore that
fact at our peril.
