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Climate Change May Bring Severe Flooding to Some Regions

New models show how global warming may increase flooding from southeast Asia to western Europe
Passau floods, Danube river flood



Flickr/Stefan Penninger

As the Danube River reaches record high levels and thousands flee Europe's worst flooding in more than a decade, scientists already are predicting that this deluge may be a portent of things to come.

In Passau, in southern Germany at the confluence of the Danube, Inn and Ilz rivers, floodwaters reached 42.3 feet over the last few days. The previous record was in 1501, when levels reached 40 feet.

Extreme weather of the kind ravaging the Danube and Elbe rivers in Central Europe is expected to become more frequent. And while experts note that individual events can't be attributed to climate change, they say Europe needs to start preparing for even worse floods.

"The E.U. needs a comprehensive strategy including flood prevention and warning systems," said Gregor Vulturius, a research associate at the Stockholm Environment Institute. "They need to increase public awareness and carry out risk mapping to ascertain where they should allocate resources."

Vulturius pointed out that flooding is influenced by social and economic conditions as well as climate. Cities need to add a layer of preparedness, such as land-use restrictions in flood-prone areas, provisions for groundwater pumping and regular dredging in some areas to minimize silt and sand deposits on riverbeds following heavy rainfall.

Cities, he said, must ready public infrastructure not just for 100-year events -- which are now occurring every few years -- but also for 500-year events. At the same time, he noted, some parts of Europe, like Dresden and Saxony in Germany, have done significant work since the last major flooding in 2002, such as placement of channels on the Elbe River to cope with runoff from an extreme flood event. The E.U. price tag for mopping up after those floods was $16.5 billion.

According to Munich Re AG, the world's largest reinsurer, the cost to insurance underwriters of the 2002 flood was $3.4 billion. To date, Munich Re has been unable to estimate what the exact cost of the 2013 floods is likely to be.

"It is still too early to evaluate the current flood catastrophe and its related losses, especially because the floodwaters have yet to drain away," said Anette Lamberts, Munich Re's head of media relations. She added that it would likely be several weeks before the company could issue a reliable figure because, despite the fact that the rain has mostly stopped, the floodwaters have not yet reached their zenith in some areas.

Changing climate means heavy weather

In northern Germany, the water is expected to rise even further before the worst is over. The Danube's waters are predicted to peak today in Hungary's capital, Budapest, and are expected to reach 29.5 feet, some 10 inches higher than the river's previous record in 2006.

Prime Minister Viktor Orban has declared a state of emergency. Thousands of volunteers worked overnight to reinforce the riverbanks, and an emergency evacuation facility capable of temporarily housing 15,000 people has been set on Budapest's fairground.

Cities will not be the only casualties. Germany's agricultural ministry estimated damages from the flooding to be in the range of $232.6 million.

The DBV, the German Farmers Association, estimates the total cost will be much higher in the neighborhood of $396.5 million. The association expects total area of farmland under water -- currently 370,658 acres -- to rise to 617,763 acres. It won't know the scope of the damage until the waters recede. These figures do not take into account the replacement cost of equipment, buildings and livestock. DBV President Joachim Rukwied announced the creation of a relief fund in conjunction with a charitable foundation to make up the shortfall.

Although scientists hesitate to draw a direct relationship between weather and climate, observation of weather patterns shows a definite correlation between extreme weather events and a warming climate.

"If we look at precipitation events over the long term, there is an increase in frequency of extremes. Events such as the one we're seeing now are occurring about twice as often as they did a century ago," said climate scientist Mojib Latif from the Helmholtz Center for Ocean Research in the German Baltic city of Kiel.

Extreme events, points out Latif, are not limited to floods. Nor are they limited by geography.

"Weather is unpredictable," said Latif. "But what we are seeing from the scientific data is instability, and not just in Europe." Africa, for example, has experienced severe flooding in the past few years with tens of thousands displaced. And extreme events are not limited to flooding.

"Drought conditions are increasing as well as flood conditions," said Latif. "We're going to be seeing many more extremes in both directions in the future. They are two sides of the same coin."

The cause of the present flood has to do with the mass of water vapor in the air, which is partly the result of higher air temperature. "The water content in the air depends on the temperature, as temperature regulates how much water can evaporate," said Latif.

The European flooding of the past few weeks was caused by a low-pressure system over eastern Europe drawing warm, moist air from the Mediterranean region. The warm water vapor concentrated north of low-lying mountain ranges and the Alps, and then condensed when it arrived in the cooler regions of central and eastern Europe. The result was torrential rainfall.

Where there are cities, there will be floods

Areas where the ground is sealed at the surface, such as roads and heavily developed urban expanses like plazas and parking lots, are at high risk for flooding. Most cities provide little in the way of a porous layer of earth or sand through which surface water can permeate.

Gerhard Lux, a meteorologist at the German Meteorological Office, told Deutsche Welle: "We had a very wet May. That means we had already seen a lot of precipitation, and the ground was completely saturated. Then we had excessive, heavy rainfall in many areas of Germany in late May and early June. The ground could not absorb it, so it had to flow off on the surface, rapidly filling streams and rivers."

In Prague, areas in the north and south of the city are under water, according to a report in The Financial Times. Metal barriers erected along the Vltava have stemmed the tide in the city's historic center, mitigating flood damage. However, large parts of the Prague underground system remained shut last week, and officials said it would not reopen for days.

Prague's central sewage-treatment plant was shut down on June 3 to prevent damage from the high water. That means sewage from the capital seeps into the river, which as of this weekend was still flooding parts of the city. The city government hopes to restart the plant within a few days.

Although floodwaters in Prague have begun to recede, the German city of Dresden is bracing itself for the river Elbe to rise 16 feet higher than normal. Dresden, whose baroque city center was swamped in the 2002 flood, hopes its remediation efforts after that flood will pay off. The Elbe River, which runs through it, has been rising relentlessly against a barrier of sandbags, and one of the bridges over the river was closed.

Footing the bill

German Chancellor Angela Merkel toured some of the worst-affected areas of flooding in Germany last week and pledged €100 million ($130 million) in immediate federal government aid, Der Spiegel reported.

Merkel was accompanied by Bavarian Gov. Horst Seehofer, who pledged an additional €50 million ($65 million) in regional aid for Bavaria. German Transport Minister Peter Ramsauer said the road and rail network alone had sustained more than €100 million ($130 million) worth of damage. The true cost of damage, he told Deutsche Verkehrs-Zeitung, could not be assessed until the water had receded.

Although Kristalina Georgieva, the E.U. commissioner for international cooperation, humanitarian aid and crisis response, tweeted a pledge of E.U. assistance in the early days of the flooding, a report in Der Spiegel provided a far less sanguine outlook about the prospect that the European Union would provide financial aid for the cleanup. On June 5, European Budget Commissioner Janusz Lewandowski told journalists in Brussels that the promises may have been premature. The bloc's Solidarity Fund, he said, is empty.

The report quoted Lewandowski as saying: "The scale of the catastrophe is absolutely beyond the reimbursement [possible] in these countries. We are without resources, for sure, for the European Solidarity Fund. In 2013 it is not possible."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500

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