快猫短视频

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鈥檚 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 (see Timeline).

Until now, the benchmark of climate change has been the Earth鈥檚 average temperature. 快猫短视频 have geared their models towards forecasting this simple measure, and used the results to shock policy makers into action. The UN鈥檚 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 掳C and 5.8 掳C 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. 鈥淧eople are fighting less about whether there is climate change,鈥� says Jonathan Gregory of the University of Reading in the UK. 鈥淚t is now more sensible to think about adapting to it.鈥�

When it comes to coping with the changes, global temperatures are essentially irrelevant. 鈥淎ll people are interested in is the regional and local details,鈥� says Rowan Sutton of the Centre for Global and Atmospheric Modelling at the University of Reading, UK 鈥� and climate science is completely unprepared for this challenge, he warns.

At the Royal Meteorological Society鈥檚 annual meeting in Norwich last week, Sutton presented his audience with a topical British example. During this summer鈥檚 heatwave, rail companies had to cancel trains, fearing tracks would buckle as the temperature soared to almost 38 掳C. 鈥淪hould Network Rail invest in upgrades to avoid future heat-induced speed restrictions?鈥� he asked. 鈥淐learly there will be a need for climate information there. What are you going to tell them?鈥�

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 (see 鈥淔uzzy forecasts鈥�).

The need for local data is urgent. According to the European Commission, droughts have already caused crop yields to drop across southern Europe (快猫短视频, 23 August, p 5). But without predictions of exactly what will happen where, farmers can鈥檛 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 (快猫短视频, 26 April, p 24). 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. 鈥淥ur aim was to come up with a national picture for 100 years鈥� time,鈥� 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. 鈥淚f we build poor houses in dumb places, the flood risk increases,鈥� 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鈥檛 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鈥檚 more, as the scale gets smaller, 鈥測ou have to completely re-evaluate the science,鈥� 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.