Potsdam, Germany (dpa) – The evidence is mounting that climatic change is leading to an increase in natural disasters. Whether floods in Asia, droughts in Africa or storms in Europe, natural catastrophes are being attributed to global warming.
If temperatures rise by a further 2 degrees Celsius, water resources in many parts of the world could become noticeably scarcer, says Hans-Joachim Schellnhuber, who heads climatic research at a scientific institute in the German town of Potsdam near Berlin.
“The earth is drying out because more water is evaporating from it,” Schellnhuber says, adding that this is being accompanied by extreme storms, rivers bursting their banks and coastal flooding.
Climatologist Hartmut Grassl believes some facts are clear. Average global warming on the earth’s surface – caused principally by carbon dioxide (CO2) emissions – amounted to an increase of between 0.5 and 0.7 degrees in the course of the 20th century, and the intensity of individual precipitation occurrences on all continents has increased.
“It rains less often, but when it does, the fall is heavier,” Grassl says. Central Europe is experiencing high winter precipitation, and in addition the polar ice is melting, with the caps shrinking both in extent and thickness over recent decades.
“It is clear that we have contributed to these changes,” Grassl says, citing the United Nations’ Intergovernmental Panel on Climate Change. He acknowledges, however, that the precise impact of human activity is not known, “as natural climatic changes are not sufficiently understood”.
“Should average temperatures change further, there will be even greater weather extremes,” Grassl says, adding that all regions becoming warmer will see new precipitation records.
A question mark hangs over whether Germany will become warmer, as this depends to a large extent on the Gulf Stream, but what is clear is that in the southwest of the country, high river levels have occurred every 10 years or so since 1950, whereas before they occurred every 50 years.
According to Schellnhuber “considerable changes” have taken place in Atlantic low-pressure systems that produce their typical high winds and precipitation over western Europe. Whereas these systems lasted 2.5 to three days before the 1970s, they now remain in place for four days.
Higher temperatures also have an impact on the global water circulation system, because more water evaporates, especially near the Equator.
According to recent data provided by the IPCC, global temperatures will rise on average by between one and 5.5 degrees during the course of this century.
As a result, sea levels will rise by between 14 and 80 centimetres. According to Schellnhuber, they rose at least two centimetres over the past decade.
A rise of 2 degrees would lead to a drop in global food production, according to IPCC researchers, among them Schellnhuber.
“We have discovered that tropical countries will be the clear losers, in particular sub-Saharan Africa, Southeast Asia, India and Latin America,”Schellnhuber says, adding that diseases like malaria and bilharzia could spread.
Schellnhuber urges a two-track strategy for keeping the greenhouse effect in check: a switch to alternative sources of energy and adaptation to the higher temperatures by changing agricultural practice in the countries worst affected.
Reducing greenhouse gases by 5 per cent in line with the Kyoto Protocol would cut the global warming effect by only 0.1 to 0.2 degrees by 2100, Schellnhuber says.
“This has only symbolic significance, and a cut of 50 to 80 per cent in carbon dioxide is necessary over the longer term.”
The solution lies in alternative forms of energy. “In my opinion large energy concerns have already realized this,” Schellnhuber says, adding that he believes solar-thermal power stations are a key part of the answer.
They do not use solar cells but rather convert the sun’s energy into electricity with the aid of air turbines or parabolic mirrors.
Schellnhuber believes that hydrogen and methanol can be produced in an environmentally sound way and in turn be converted into electricity with the aid of fuel cells without producing noxious exhaust gases.
“This will result in clean air in cities and help the climate,” he says.
Industrialized countries should convert their energy production to alternative sources at a rate of 1 percentage point a year. “If we manage to halt the warming effect at up 2 degrees on the level in 2000, then we will have fulfilled our aim,” Schellnhuber says.
