Climate and land use: Europe's floods raise questions

Jun 05, 2013 by Richard Ingham
A man sits at a flooded street in Putim, near Pisek, Czech Republic, on June 5, 2013. Less than three months after being battered by snow and ice, central Europe now finds itself fighting floods—and some scientists are pointing the finger at human interference with the climate system.

Less than three months after being battered by snow and ice, central Europe now finds itself fighting floods—and some scientists are pointing the finger at human interference with the climate system.

Leading the charge is the Potsdam Institute for Climate Impact Research (PIK) near Berlin, which says a low-pressure system that dumped the rain was locked into place by a disturbance with a global wind pattern.

"We think it is linked to the current in Russia as well," Stefan Rahmstorf, PIK's professor of ocean physics, told AFP.

Normally, air moves around the mid-latitudes of the planet in the form of waves, oscillating irregularly between the tropics and the poles, Rahmstorf explained.

The main force behind this movement is the big temperature gap between the frigid Arctic and the warmer southerly latitudes. Like a pump, this differential helps to force air northward or southward.

The problem, though, is that the Arctic is steadily warming—last year, its summer sea ice hit its lowest extent on record—so the temperature difference is declining.

As a result, according to the theory, the wave movement diminishes. At a certain point, pressure systems stay locked in place, causing a that persists wretchedly.

"This planetary wave resonance is not a local effect but spread around the whole (northern) hemisphere," said Rahmstorf in an email exchange.

When a "resonance" episode occurs, half a dozen peaks and troughs of high or low pressure form around the hemisphere. This explains why some parts of the world become unseasonably hot or cold and others unusually dry or rainy, said Rahmstorf in an email exchange.

More and more of these events have been occurring since 2003, coinciding with higher temperatures and widening loss, Rahmstorf said. Current data from point to a repeat of this episode, he added.

The resonance theory has become widely discussed among since PIK first published it in the scientific journal Nature Climate Change last year.

An aerial view shows a flooded house near Meissen, eastern Germany on June 5, 2013.

But it has met resistance among experts who are leery about associating a single extreme-weather event today—or even several—with climate change, which is considered a longer-term phenomenon.

"To confirm the exact role played by in flooding trends in past decades, it would be necessary to have more reliable, long-term series data for a rivers with a natural flow regime," the European Environment Agency (EAA) cautioned on Wednesday.

It said, though, that as far as the future is concerned, rising temperatures in Europe will accentuate rainfall, "leading to more frequent and intense floods in many regions."

According to a probe by European hydrologists, around a fifth European cities with a population of more than 100,000 are very vulnerable to river flooding, a risk that raises questions about how land is used.

Concrete and tarmac ensure that rainfall drains off very quickly into rivers, whose levels may rise swiftly if farmland is already soggy—as was the case in much of central Europe after last March's snowfalls.

The green group WWF called for a restoration of flood plains, a natural buffer against floodwaters that for decades has been eroded by urbanisation and agriculture.

Austria, it noted, was enduring its second big flood in 10 years. Yet each day, the equivalent of around 12 football pitches of Austrian land were being sealed over, especially in river valleys.

"Flood plains are like sponges allowing large volumes of water to be stored and slowly and safely released down rivers and into the groundwater," said Orieta Hulea, WWF's conservation director for central and eastern Europe.

"If we cut them off from the main river beds and drain them for agriculture, as has happened on the Lower Danube and across most of Europe for the last century, their potential for flood retention is lost and the risks from floods are increased."

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Neinsense99
3.3 / 5 (14) Jun 05, 2013
The usual suspects will be along shortly with "the science is not settled", "Al Gore is a crook", it's been cooling, etc., blah blah blah...
antigoracle
1.6 / 5 (14) Jun 05, 2013
The usual suspects will be along shortly with "the science is not settled", "Al Gore is a crook", it's been cooling, etc., blah blah blah...

Of course the AGW Alarmist morons are first with absolutely nothing but insults.
This is exactly the kind of event the AGW Alarmist seek so they can prey on the concern and suffering of people.
VENDItardE
1.7 / 5 (12) Jun 05, 2013
neinsense is so appropriate a name for an idiot without a lick of sense
Sinister1811
2.7 / 5 (11) Jun 05, 2013
Climate change is exactly what is causing floods around the world. Agree, or disagree - it really makes no difference to the reality.
Howhot
4.4 / 5 (7) Jun 06, 2013
OH the great @anti whose oversize feet only hints of the owners massive girth measure by belt size; says "Of course the AGW Alarmist" etc. One can only suppose that his intellect is like the sandals his hobbit like foot wears; at the bottom of his feet.

Anyone that knows anything about AGW knows this flooding event was caused by CO2 global warming. Its as plain as the nose on your toad stool shaped head.

antigoracle
1.4 / 5 (11) Jun 06, 2013
OH the great @anti whose oversize feet only hints of the owners massive girth measure by belt size; says "Of course the AGW Alarmist" etc. One can only suppose that his intellect is like the sandals his hobbit like foot wears; at the bottom of his feet.

Anyone that knows anything about AGW knows this flooding event was caused by CO2 global warming. Its as plain as the nose on your toad stool shaped head.


The AGW Alarmist stupidity knows no limit. By your reasoning, the US should be covered in floods.
Howhot
4.5 / 5 (8) Jun 06, 2013
With a flagellant presents the extremist @anti barks like an annoying rodent;
By your reasoning, the US should be covered in floods.
Flooding is a very common effect of AGW. Simply a warmer global atmosphere evaporates more water which lofts higher by stronger thermal currents, causing droughts in some areas, but also causing trends where it rain harder when it does rain. Floods and droughts are expected from global climate change from increased CO2 from humans burning fossil fuels.