- Registration time
- Last login
- Online time
- 3587 Hour
- Reading permission
There is no doubt that there will be droughts in other parts of the world, especially in subtropical regions. But the widespread assumption that it is developing countries -- that is, the world's poor -- who will, as always, be the ones to suffer is incorrect. According to current predictions, precipitation in large parts of Africa will hardly decrease at all, except in the southern part of the continent. In fact, these same forecasts show the Sahel, traditionally a region beset by drought and famine, actually becoming wetter.|
By contrast, some wealthy industrialized nations -- in fact, those principally responsible for climate change -- will likely face growing problems related to drought. The world's new drought zones lie in the southern United States and Australia, but also in Mediterranean countries like Spain, Italy and Greece.
All of this will lead to a major shift within Europe, potentially leading to tough times for southern Spain's mega-resorts and boom times for hotels along the North Sea and Baltic Sea coasts. While the bulk of summer vacationers will eventually lose interest in roasting on Spain's Costa del Sol, Mediterranean conditions could prevail between the German North Sea island of Sylt and Bavaria's Lake Starnberg. The last few weeks of spring in Germany offered a taste of what's to come, as sun-loving crowds packed Berlin's urban beach bars and Munich's beer gardens.
The predicted temperature increase of 3 degrees Celsius would mean that summers in Hamburg, not far from the North Sea coast, would be as warm as they are today in the southwestern city of Freiburg, while conditions in Freiburg would be more like those in Marseille today. Germany will undoubtedly be one of the beneficiaries of climate change. Perhaps palm trees will be growing on the island of Helgoland in the North Sea soon, and German citizens will be saving billions in heating costs -- which in turn would lead to a reduction in CO2 emissions.
But climate change will also have its drawbacks. While German summers will be less rainy, fall and winter rainfall in the country's north will increase by up to 30 percent -- and snow will be a thing of the past. Heavy downpours will also become more common. To avoid flooding, steps will have to be taken to provide better drainage for fields and farmlands, as well as to restore natural flood plains.
Meanwhile, the Kiel Institute for World Economics warns that higher temperatures could mean thousands of heat-related deaths every year. But the extrapolations that lead to this dire prediction are based on the mortality rate in the unusually hot summer of 2003, for which Germans were wholly unprepared. But if hot summer days do become the norm, people will simply adjust by taking siestas and installing air-conditioning.
The medical benefits of higher average temperatures have also been ignored. According to Richard Tol, an environmental economist, "warming temperatures will mean that in 2050 there will be about 40,000 fewer deaths in Germany attributable to cold-related illnesses like the flu."
Another widespread fear about global warming -- that it will cause super-storms that could devastate towns and villages with unprecedented fury -- also appears to be unfounded. Current long-term simulations, at any rate, do not suggest that such a trend will in fact materialize.
"According to our computer model, neither the number nor intensity of storms is increasing," says Jochem Marotzke, director of the Hamburg-based Max Planck Institute for Meteorology, one of the world's leading climate research centers. "Only the boundaries of low-pressure zones are changing slightly, meaning that weather is becoming more severe in Scandinavia and less so in the Mediterranean."
According to another persistent greenhouse legend, massive flooding will strike major coastal cities, raising horrific scenarios of New York, London and Shanghai sinking into the tide. However this horror story is a relic of the late 1980s, when climate simulations were far less precise than they are today. At the time, some experts believed that the Antarctic ice shield could melt, which would in fact lead to a dramatic 60-meter (197-foot) rise in sea levels. The nuclear industry quickly seized upon and publicized the scenario, which it recognized as an argument in favor of its emissions-free power plants.
But it quickly became apparent that the horrific tale of a melting South Pole was nothing but fiction. The average temperature in the Antarctic is -30 degrees Celsius. Humanity cannot possibly burn enough oil and coal to melt this giant block of ice. On the contrary, current climate models suggest that the Antarctic will even increase in mass: Global warming will cause more water to evaporate, and part of that moisture will fall as snow over Antarctica, causing the ice shield to grow. As a result, the total rise in sea levels would in fact be reduced by about 5 cm (2 inches).
It's a different story in the warmer regions surrounding the North Pole. According to an American study published last week, the Arctic could be melting even faster than previously assumed. But because the Arctic sea ice already floats in the water, its melting will have virtually no effect on sea levels.
Nevertheless, sea levels will rise worldwide as higher temperatures cause the water in the oceans to expand. In addition, more water will flow into the ocean with the gradual thawing of the Greenland ice sheet. All things considered, however, in the current IPCC report climatologists are predicting a rise in sea levels of only about 40 centimeters (16 inches) -- compared with the previous estimate of about one meter (more than three feet). A 40-centimeter rise in sea levels will hardly result in more catastrophic flooding. "We have more computer models and better ones today, and the prognoses have become more precise as a result," explains Peter Lemke of the Alfred Wegener Institute for Polar and Marine Research in the northern German port city of Bremerhaven.
Some researchers do, however, estimate that regional effects could produce an 80-centimeter (31-inch) rise in the sea level along Germany's North Sea coast. This will lead to higher storm surges -- a problem the local population, already accustomed to severe weather, could easily address by building taller dikes.
Another comforting factor -- especially for poorer countries like Bangladesh -- is that none of these changes will happen overnight, but gradually over several decades. "We still have enough time to react," says Storch.
In short, the longer researchers allow their supercomputers to crunch the numbers, the more does the expected deluge dissipate. A rise in sea levels of several meters could only occur if Greenland were largely ice-free, but this is something scientists don't expect to happen for at least a few more centuries or even millennia. This lengthy timeframe raises the question of whether the current prognoses are even reliable.
A healthy dose of skepticism is a good idea, especially when scientists become all too confident and make themselves out to be oracles. But there can be a wide gap between their predictions and the end result -- a fundamental weakness of all computer simulations that present only incomplete pictures of reality.
Sign up for Spiegel Online's daily newsletter and get the best of Der Spiegel's and Spiegel Online's international coverage in your In- Box everyday.
In the early years, for example, computer modelers underestimated the influence of aerosols, especially the sulfur particles that are released into the atmosphere during the combustion of oil and coal or during volcanic eruptions. These pollution particles block sunlight and thus cause significant cooling. The failure to adequately take aerosols into account explains why earlier models predicted a more drastic rise in temperatures than those in use today. One major unknown in the predictions depends on how quickly countries like China will filter out the pollutants from their power plant emissions -- if the air becomes cleaner it will also heat up more rapidly.
Other factors that can either weaken or strengthen the greenhouse effect are still not fully understood today. For example, will the carbon dioxide trapped in the world's oceans be released as the water heats up, thereby accelerating global warming? And how much faster do land plants and sea algae grow in a milder climate? Plant proliferation could bind more carbon dioxide -- and serve to slow down the greenhouse effect.
But the main problem lies in correctly calculating the effects of clouds. The tops of clouds act as mirrors in the sky, reflecting sunlight back into space -- thus cooling the planet. But the bottom sides keep the heat radiated by the earth from escaping into the atmosphere -- causing temperatures to rise.
Which of the two effects predominates depends primarily on the altitude at which clouds form. Simply put, low clouds tend to promote cooling while high clouds increase warming. So far scientists agree on only one thing, namely that more clouds will form in a greenhouse climate. They just don't know at which altitude.
Even the most powerful computer models are still too imprecise to simulate the details. However, the clouds alone will determine whether temperatures will increase by one degree more or less than the average predicted by the models. This is a significant element of uncertainty. "Clouds are still our biggest headache," concedes Erich Roeckner of the Max Planck Institute for Meteorology.
Roeckner is a conscientious man and a veteran of climate research, so he, of all people, should know the limits of simulation programs. Roeckner, who constantly expects surprises, neatly sums up the problem when he says: "No model will ever be as complex as nature."
Translated from the German by Christopher Sultan