What's causing the record-bad floods in Russia?

PARIS, France — What is driving the record-bad flooding that has devastated parts of Russia and Kazakhstan and forced tens of thousands of people to escape the fast-rising water?

AFP looks at the worst flooding in decades to hit this region:

Spring floods in Russia and northern Kazakhstan "are to be expected and are a regular occurrence", said Maria Shahgedanova, a climate scientist at the University of Reading.

This region endured similar major floods in 1922, 1942 and 1957 though the current disaster was "extraordinary and all previous 'records' have been surpassed", she added.

The Ural River flooded Russia's Orenburg region in particular, while the Ishim -- which feeds the Siberian regions of Tyumen and Omsk, and northern Kazakhstan -- also burst its banks.

The cause is primarily the rapid onset of warm spring weather meeting lots of winter snow, causing a sudden melt and quick filling of rivers.

Shahgedanova said about half of all floods in this region have started this way, with another third attributed to rainfall and about 15 percent due to ice blockages in rivers.

This region of Russia and Kazakhstan experienced above-average snowfall this past winter, with snow depth exceeding normal levels by 60 percent in some areas.

Shahgedanova said this was followed by a sudden jump in temperatures from below zero to nearly 20 degrees Celsius in a matter of days as spring arrived.

This rapid shift compounded by heavy rainfall "exacerbated the already critical situation" by quickly turning that excess snow into enormous volumes of water.

"This is a case of a perfect storm," she said.

Scientists are in agreement that global warming caused by rising levels of greenhouse gases in the atmosphere is driving more extreme weather, including floods.

But "there is no clear trend towards more frequent floods" in this particular part of Russia and Kazakhstan, said Shahgedanova.

"I would attribute it... to climatic variability, as opposed to a more long-term change, which may be a natural process," she said.

A clearer link has been established between global warming and the increased likelihood of floods during the winter months in northwestern Europe, Shahgedanova added.

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