鈥淎ND now, the weather for the next decade.鈥� It sounds wildly optimistic, but
meteorologists could be offering such forecasts within 20 years.
In Paris last week, researchers from 60 countries unveiled an international
programme of research into climate variability called CLIVAR which could help
predict the world鈥檚 weather for years ahead. But they warned that it will only
happen if their governments contribute 鈥渉undreds of millions of pounds鈥�. CLIVAR
will operate under the UN鈥檚 World Climate Research Programme but has no
independent funds.
The scientists, meeting at the headquarters of the UN鈥檚 science organisation
UNESCO, cast aside the view that the weather was inherently chaotic and
unpredictable. They said there were recurrent patterns, and they were close to
understanding those patterns. 鈥淲e can start to see into the future. This really
is a revolution,鈥� said Ed Sarachik, an oceanographer at Seattle University who
helped to write the plan for CLIVAR.
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The aim of CLIVAR is to root out the 鈥渉idden hand鈥� behind the climate
variability that causes droughts and tropical storms and determines the strength
and frequency of monsoons, El Ni帽o and less well-known fluctuations such
as the North Atlantic Oscillation. For much of the world鈥檚 weather, the hidden
hand is in the oceans. Fluctuations in ocean circulation and temperatures happen
much more slowly than in the atmosphere, but through the exchange of heat and
water vapour they drive much of what happens in the air. If you can predict the
ocean, so the thinking goes, you can predict the weather.
The researchers鈥� optimism comes from their recent successes in using
observations and computer models to predict El Ni帽o. This followed a
10-year international research project known as the Tropical Ocean Global
Atmosphere (TOGA), which deployed ocean-monitoring buoys across the Pacific. The
buoys revealed an unusual warming beneath the surface of the ocean which
computer models interpreted as the precursor to El Ni帽o.
Now the researchers want to apply the same techniques to predict other
patterns in the weather, such as the North Atlantic Oscillation. The NAO is a
fluctuation in pressure over the North Atlantic and is responsible for up to
half of all the climate variability in western Europe, causing droughts, floods and storms
(鈥淭he Storm in the Machine鈥�, New 杏吧原创, 31 January, p 22).
What intrigues forecasters is that while the NAO can change wildly from week
to week, it has long-term patterns. Climatologists believe that these patterns
are determined by changes in ocean currents. 鈥淢y vision is to get predictions of
these major features a decade ahead,鈥� said Hartmut Grassl of the World Climate
Research Programme in Geneva.
