Rising tides threaten to sink Earth’s megacities

Water, water, everywhere: Major cities on all continents are threatened by flooding.

Experts warn that vast numbers of people living in urban areas are at risk of losing their homes to severe flooding. Must they abandon the cities and seek safety in the hills?

Sam Notaro had toiled tirelessly to pile up a five-feet mud wall around his house and garden. But finally, he could only look on as water breached the perimeter, and the immaculate lawn became like most of Somerset, a bog.

Like Sam, for the past two months Britons have battled record rainfall. Over 5,000 properties have been damaged and 1.6m more are considered at risk. The sheer scale of the deluge has prompted worries that floods will become the norm.

Britain is not the only country facing the problem. Experts warn that we should expect global devastation in the coming years. From New York to Bangkok, Manila to Venice, the world’s cities face devastation.

The cost of dealing with the floods will be astronomical. One report has forecast that by 2100, coastal cities will need to pay $1 trillion in damages annually if changes are not made. This is more money than the Netherlands makes each year.

Yet cities have traditionally prospered close to waterways. Water allowed farmers to irrigate their crops and provided a means of transport and commerce at a time when travelling by ship was faster than by land. It was their huge ports that made New York, Hong Kong and London into global centres. Then success bred success as these cities drew talented immigrants.

Now, it is the popularity of major cities that has put them at so much at risk. Studies show clear links between population density and flooding as fields and forests are replaced with urban concrete. The UN expects this to get particularly worse in Africa, where the city population will have tripled by 2050 as rural populations look for jobs in urban centres.

Urbanisation coupled with rising sea levels due to global warming is a disastrous cocktail. By the end of the century sea levels are expected to rise by 2.3m, which may well swamp New York, Guangzhou and Mumbai.

As our cities face stern tests, scientists are imploring governments to take action. But what is to be done?

High Tide

Some believe that it is time to reverse the traditional pattern of living by the waterside and move to new safer urban centres in the hills. We no longer rely on ships for travel or rivers to grow crops, and modern wonders have sprung up in Las Vegas and Dubai without a river in sight.

‘Madness!’ others cry. Defending our cities will come at considerable cost, but entire generations of families cannot be uprooted from their homes. Flood barriers, skyscrapers on stilts – these are the adaptations we need to make. Making our cities suitable for the changing conditions will be expensive, but not impossible.

You Decide

  1. Would you rather move to safety or risk floods in the city?
  2. ‘The UK should stop sending £12 billion of aid abroad each year and focus on its own problems.’ Do you agree?


  1. Split into groups of four. Imagine how life might be different in a city of the future.
  2. Research flood control methods used around the world and design a flood-safe city.

Some People Say...

“We forget the water cycle and the life cycle are one. Jacques Cousteau”

What do you think?

Q & A

At least my house isn’t flooded!
Global flooding still affects everyone on the planet. Housing prices will rise in places away from the floods, meaning more competition for homes in those areas. Countries with higher land will witness a surge in immigrants from lower areas. And global trade would be affected, which would disrupt the import of food and other vital goods.
So are more floods on the way in the UK?
Senior government adviser Sir David King has warned that the UK should expect much more severe weather in the years to come and that we need to double spending on flood defences to £1 billion a year by 2020. He added that whereas the UK used to see extreme weather maybe once every 100 years, we should now expect it much more frequently thanks to climate change.

Word Watch

A report in the Hydrological Sciences Journal estimates that almost 1 in 7 people currently lives in areas vulnerable to flooding. Scientists say that flooding, even with prevention measures in place, will cost the world’s coastal cities vast sums of money.
New York
The Statue of Liberty is an iconic symbol of America’s cultural melting pot as for many immigrants arriving on ships, it was the first sight they had of their new home. New York City’s population is now a hundred times larger than it was 200 years ago.
Hong Kong
The city was founded by the British in 1842 and was intended as the empire’s major trading port in the Far East. Since then it has grown to be one of the most densely populated places on Earth with a population of over seven million.
Rising sea levels
One solution to the problem is sea barriers, but these come at tremendous expense. The Thames Barrier has been safeguarding London for over 30 years and protects 48 square miles of central London from flooding. Other cities are considering similar measures. Swansea has submitted plans for an £850m ‘lagoon’ which could be used to control the sea level while generating electricity.


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