Download New Scientist Sept 13, 2003

New Scientist
September 13, 2003
SECTION: News; This Week; Pg. 6
LENGTH: 1364 words
HEADLINE: Global warming: the new battle;
It's time to accept that climate change is unstoppable, but working out how to adapt to it won't be
easy
BYLINE: Jenny Hogan
BODY:
STOP debating whether global warming is happening. The priority now is to start preparing for
its consequences, be they droughts and heatwaves or floods and harsh winters. That is the
message from meteorologists, who say adapting to climate change will be one of the world's
major challenges for the 21st century.
It marks an astonishing shift in how experts view global warming. Confident that they have all
but convinced the world that warming is taking place, climate scientists are concentrating on
predicting its local effects. The problem, they say, is that so far we have no way of knowing what
those effects will be.
Pushing the idea of adapting to climate change is not popular with all climate scientists, and
some worry that it could detract from protecting the environment. But Mike Hulme, director of
the Tyndall Centre for Climate Change Research in Norwich, UK, is one of those who argue that
decisions made now will affect us for decades to come as temperatures rise. Changes to the
climate affect all areas of human activity, he points out, from what clothes people are likely to
buy next summer to long-term plans for transport, flood defences and agriculture .
Until now, the benchmark of climate change has been the Earth's average temperature. Scientist
have geared their models towards forecasting this simple measure, and used the results to shock
policy makers into action. The UN's Intergovernmental Panel on Climate Change collects
predictions from centres around the world, and in its 2001 report concluded that human activity
is likely to cause the average global temperature to rise by between 1.4 degreesC and 5.8
degreesC by 2100.
Politicians responded with efforts to curb greenhouse gas emissions and promote renewable
energy. And with refinements to the global picture appearing almost every week, climate
scientists feel there is now an urgent need to move on. "People are fighting less about whether
there is climate change," says Jonathan Gregory of the University of Reading in the UK. "It is
now more sensible to think about adapting to it."
When it comes to coping with the changes, global temperatures are essentially irrelevant. "All
people are interested in is the regional and local details," says Rowan Sutton of the Centre for
Global and Atmospheric Modelling at the University of Reading, UK -- and climate science is
completely unprepared for this challenge, he warns.
At the Royal Meteorological Society's annual meeting in Norwich last week, Sutton presented
his audience with a topical British example. During this summer's heatwave, rail companies had
to cancel trains, fearing tracks would buckle as the temperature soared to almost 38 degreesC.
"Should Network Rail invest in upgrades to avoid future heat-induced speed restrictions?" he
asked. "Clearly there will be a need for climate information there. What are you going to tell
them?"
There was silence. Answering this question would require climate models that can predict peak
temperatures in the region of south-east England where the problem occurred. This is not
something current models are capable of. Even when answers can be given, the uncertainties are
often huge .
The need for local data is urgent. According to the European Commission, droughts have already
caused crop yields to drop across southern Europe . But without predictions of exactly what will
happen where, farmers can't prepare for the future.
The floods that devastated central Europe in August 2002 are another example. The industries
left to clean up after the river Elbe flooded were eager to blame global warming . Were they right
and should we prepare for more of the same? Research published this week that re-examines
historical records of the area concludes that summer floods around the river have not increased,
while winter floods have become less common (Nature, vol 425, p 166). This fits climate
models, which suggest warmer surface temperatures stop the river from freezing in winter,
making it less likely to become blocked by breaking ice.
Add social factors to the mix, and the picture changes again. Edmund Penning-Rowsell, head of
the Flood Hazard Research Centre at Middlesex University and his colleagues reported the
results of a study of flood risk in the UK at the annual meeting of the Royal Geographical
Society in London last week. "Our aim was to come up with a national picture for 100 years'
time," says Penning-Rowsell. The researchers included factors such as population density, land
use and flood defences and found that even though global warming seems to be reducing the risk
of severe floods, the risk facing Londoners and people living along the coast of south-east
England looks set to rise significantly over the next century. "If we build poor houses in dumb
places, the flood risk increases," says Ilan Kelman, part of the research team. The worst-case
scenario predicts that an extra million people in the UK will be at high risk by the 2080s.
Detailed local information about climate change will be invaluable for studies like these. But
getting it right won't be easy. Because local climate is heavily dependent on what is happening
elsewhere, the whole planet has to be included just to look at one particular place.
Running the existing global models at higher resolution would take more computing power than
we have. Even the Earth Simulator in Japan, the most powerful supercomputer ever built,
struggles to reach a resolution of 10 kilometres. What's more, as the scale gets smaller, "you have
to completely re-evaluate the science," says Alan Thorpe, who chaired the Norwich conference.
Local models will need to include features such as clouds and mountain ranges, and make
different compromises from global models, embedding a high-resolution local model within a
lower-resolution global one, say.
For climate scientists, there is a huge task ahead. So far, says Sutton, hardly anyone is working
on solving these problems.
Fuzzy forecasts
Jenny Hogan
One thing climate modellers don't tend to let on is how confident they are in their results. "We
just give the forecast, with no idea of how likely or unlikely that outcome is," says Mat Collins
from the UK's Hadley Centre for Climate Prediction and Research in Bracknell, Berkshire. But
that won't be good enough to base decisions on, he warned colleagues at the Royal
Meteorological Society meeting in Norwich last week.
Putting error bars on climate forecasts is one of next challenges for the field, says Collins.
"There seems to be a body of agreement that this is a real priority." Collins and his team
presented the first results from a project that aims to quantify the uncertainty in their climate
model. They tweaked various settings, such as the parameters describing clouds or convection,
then checked to see whether the new versions of the model matched today's global climate. The
researchers took the 53 that did, and ran them forward to predict how temperatures will change if
levels of carbon dioxide in the atmosphere double. The different versions predicted temperature
increases of anywhere from 1.8 degreesC up to 8.3 degreesC - a far wider spread than the
Intergovernmental Panel for Climate Change's prediction of 1.5 to 4.5 degreesC, which is based
on results from all the 10 or so climate models run around the world. In the short term at least,
says Collins, we will have to accept that climate prediction will become less certain.
The drawback of this approach is that running several versions of a model eats up computer time
that could be used to make more precise forecasts. But a unique project to be launched this week
could help climate modellers do a little more. Climateprediction.net will use idle time on
people's computers to calculate how the climate is going to change. Each volunteer runs a
slightly different model, and the results are sent back for comparison.
Anyone can download the software at www.climateprediction.net and watch the weather patterns
on screen as they take part in what the organisers hope will be the largest distributed computing
project in the world.
Additional reporting by Carolyn Fry
LOAD-DATE: September 15, 2003