WE ARE all lucky to be alive. If industry had used bromine instead of its
close relative chlorine in aerosols and refrigerants, we would have had
something far worse than an ozone hole. The entire upper atmosphere would have
lost its ozone by the mid-1970s, Nobel prizewinner Paul Crutzen told the
conference.
We may not be so lucky next time. Crutzen warns that the early signs of other
environmental catastrophes could be going unnoticed.
Crutzen of the Max Planck Institute for Chemistry in Mainz, Germany, won a
Nobel prize in 1995 for his pioneering research into how chlorine burnt a hole
in the Antarctic ozone layer in the 1980s. We were lucky to escape far worse, he
says. Bromine would have done the job much more quickly and thoroughly.
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Chlorine compounds need ice particles to destroy ozone in large quantities,
which is why ozone holes have appeared over the Arctic and Antarctic at the end
of each winter. 鈥淏romine doesn鈥檛 need ice particles,鈥� he says.
We are increasingly likely to be wrong-footed by environmental catastrophes,
says Crutzen, because scientists studying the atmosphere tend to ignore
unexpected observations.
The researchers often throw away data that does not fit the predictions of
their models, he claims. 鈥淭hat is very dangerous. Such data is often the most
important. They threw away the first data on ozone holes,鈥� he says.
The destruction of the ozone layer was a classic case of an unforseen
environmental disaster. The holes appeared where ozone destruction was least
expected. 鈥淲hat else waits for us round the corner?鈥� he asks.
Crutzen says most models of the atmosphere ignore the biggest pollution
danger鈥攚hat effect the massive burning of tropical forests and grasslands
is having on atmospheric chemistry.
Some 9 billion tonnes of biomass is burnt each year, he says. Biomass fires
started deliberately to clear land are causing near-permanent smogs that spread
out from Asia and Africa, smothering much of the Indian Ocean, says Crutzen.
The smogs contain high concentrations of ozone and soot, which absorb
different wavelengths of light and much of the Sun鈥檚 heat. This could upset the
climate and might damage the Asian monsoon.
Typically, this pollution prevents 10 to 15 per cent of solar radiation from
reaching the surface of the land and ocean. 鈥淲e found thick brown smog 4000
metres up in the Himalayas, over the Maldives in the Indian Ocean, and widely
across south and east Asia. 鈥淲e were shocked,鈥� he says.
鈥淢ost studies have neglected this,鈥� Crutzen complains. The biomass smogs
could also use up hydroxyl, the chemical that cleans pollution out of the
atmosphere. Most of the hydroxyl in the atmosphere is generated in tropical
regions.