As communities around the world battle severe floods in living memory, experts warn such events may become more frequent due to climate change and that lessons still need to be learned to limit losses.
Floods may result in lower death tolls than earthquakes, wars or tsunamis — and therefore gain less international attention — but they can cause similar devastation.
"It would be wrong to deny the possible impact of climate change on flooding because if we (waited for more) statistical proof it may be too late," said Wolfgang Grabs at the World Meteorological Organization, a United Nations agency.
Warmer air can hold more water and will unleash more energy when the weather turns bad, Grabs said, making storms heavier and boosting rainfall.
That mechanism may well explain an observed rise in flash floods in Europe over the last decade, he said.
Recent weeks have seen a string of such disasters around the globe.
Parts of China had the heaviest rainfall since records began, killing more than 700 so far this year. Some 770 people have been killed by flooding in South Asia, with hundreds of thousands displaced by flash floods in southern Pakistan.
'No time to react' in Pakistan
"They had no time to react," said UNICEF spokeswoman Kathryn Grusovin from the affected province of Baluchistan. "They hadn't seen rains like this in living memory. There had been episodes of flooding but this was right off the map. You are talking massive amounts of rain that has never been seen before."
It is a similar story around the globe.
Thousands have had to flee homes in northern England as the water rose. More than 50 people were killed in Sudan last week. In Colombia, slums disappeared under rising floodwaters and some 50,000 people were displaced.
Experts say the worldwide floods are probably linked. One explanation could be strong waves in the jet stream, high in the atmosphere.
"There are certain configurations that can produce flooding simultaneously in different parts of the world," said Professor Colin Thorne, head of physical geography at England's Nottingham University.
Climate change could make the problem worse, he warned. Many scientists say the world is warming because of carbon emissions from human activity, making weather more unpredictable.
"You can't attribute particular events to climate change," Thorne said. "But on the other hand, the conditions that promote serious flooding will become much more frequent than they are now so the probability is we will have more extreme events."
'Something is changing'
Floods killed more than 7,000 people in the world last year, a recent study by reinsurance group Swiss Re study showed -- roughly a third of all victims of natural catastrophes such as storms, earthquakes, droughts and extreme cold or heat.
Statistics gathered by insurers — who look at the cost of a catastrophe to measure its severity, not the death toll — also indicate climate is changing.
"One single event can never be a sign of climate change," said Jens Mehlhorn, who heads a team of flood experts at the Zurich-based company.
"But when you see a series of such events, and that's what it looks like at the moment ... it may be about time to say something is changing," he said.
This year's floods in Britain were an event statistical models say should happen once only every 30 to 50 years, Mehlhorn says, and floods in 2000 were a 25-30 year event.
Two such events in only seven years are not statistically impossible, but they are unlikely. Other countries have seen similar increases in such disasters.
Huge strides have been made in coping with the consequences.
A couple of decades ago, floods in Bangladesh used to kill thousands, almost all from disease. Now, cholera outbreaks after floods have been almost eradicated, mainly through better access to sanitation and public education.
When floods hit Mozambique earlier this year, aid workers say the government was swift to broadcast radio warnings and evacuate people from vulnerable areas. Some 45 people died, compared to 700 in 2000-2001.
But experts say many lessons still need to be learned and warn that flood defenses have sometimes created a false sense of security, particularly in the most developed countries.
"With floods, the first thing to learn is that you cannot stop them," said Professor Graham Chapman at Lancaster University. "You have to have a society that learns to live with them."
Rural communities from the Zambezi in southern Africa to Bangladesh traditionally used small mounds of raised ground to escape floodwater, but rapid urbanization and reliance on dykes and embankments built by European colonizers have reduced the emphasis on traditional coping strategies.
Raised railway lines or roads can limit drainage and stop water escaping — which is why they are so often swept away, experts say. And yet post-disaster Western aid frequently concentrates on rebuilding them exactly as they were before.
Drainage is often inadequate, while building is carried out without regard to flood patterns. Sometimes there is no long-term flood planning at all.
Experts recommend building houses that are more durable and survivable as well as capable of being brought back into use within a couple of months instead of over a year.
Failings in the response to Hurricane Katrina in 2005 showed that even a developed country like the United States could fall short in the face of widespread flooding if it is not fully prepared.
While Britons ponder whether homes should still be being built on flood plains, in the Netherlands — where many live on land well below sea level — people in some cities are building floating houses and houses on stilts.
The country is also upgrading a 20-mile-long dyke at a cost of $1 billion that protects much of the land.
If such protection is on offer, flood plains should not be a bad place to live most of the time, said Notthingham's Thorne.
"Flood plains are not bad places to live 99 per cent of the time," he said. "Most of the world's great civilizations grew up along rivers — people are always going to live there. But you have to have plans for flooding."