As soon as he arrived at Dubai airport, his passport was taken from him by his construction company. He has not seen it since. He was told brusquely that from now on he would be working fourteen hour days in the desert-heat - where Western tourists are advised not to stay outside for even five minutes in summer, when it hits 55 degrees - for 500 durhams a month (£90), less than a quarter of the wage he was promised. If you don't like it, the company told him, go home. "But how can I go home? You have my passport, and I have no money for the ticket," he said. "Well, then you'd better get to work," they replied.

The work is "the worst in the world," he says. "You have to carry 50kg bricks and blocks of cement in the worst heat imaginable ... This heat - it is like nothing else.

Since the credit crunch, they say, the electricity has been cut off in dozens of the camps, and the men have not been paid for months. Their companies have disappeared with their passports and their pay. "We have been robbed of everything. Even if somehow we get back to Bangladesh, the loan sharks will demand we repay our loans immediately, and when we can't, we'll be sent to prison."

"This is the best place in the world to be young! The government pays for your education up to PhD level. You get given a free house when you get married. You get free healthcare, and if it's not good enough here, they pay for you to go abroad. You don't even have to pay for your phone calls. Almost everyone has a maid, a nanny, and a driver. And we never pay any taxes. Don't you wish you were Emirati?"

For Emiratis, this is a Santa Claus state, handing out goodies while it makes its money elsewhere: through renting out land to foreigners, soft taxes on them like business and airport charges, and the remaining dribble of oil.

The Middle East will be far more dangerous if Dubai fails. Our export isn't oil, it's hope. Poor Egyptians or Libyans or Iranians grow up saying - I want to go to Dubai. We're very important to the region. We are showing how to be a modern Muslim country. We don't have any fundamentalists here. Europeans shouldn't gloat at our demise. You should be very worried.... Do you know what will happen if this model fails? Dubai will go down the Iranian path, the Islamist path."

All the guidebooks call Dubai a "melting pot", but as I trawled across the city, I found that every group here huddles together in its own little ethnic enclave

All over Dubai, crazy projects that were Under Construction are now Under Collapse. They were building an air-conditioned beach here, with cooling pipes running below the sand, so the super-rich didn't singe their toes on their way from towel to sea.

This is the most water-stressed place on earth, according to the UN - yet it is littered with sprinklers, giant artificial ski-slopes frozen to create real snow, and tanks filled with dolphins.

Environmental Director of the Gulf Research Centre, sits in his Dubai office and warns: "This is a desert area, and we are trying to defy its environment. It is very unwise. If you take on the desert, you will lose."

There is no surface water, very little aquifer, and some of the lowest rainfall in the world. So Dubai drinks the sea. The Emirates' water is stripped of salt in vast desalination plants around the Gulf - making it the most expensive water on earth.

Dubai had expanded so fast its sewage treatment facilities couldn't keep up. The sewage disposal trucks had to queue for three or four days at the treatment plants - so instead, they were simply drilling open the manholes and dumping the untreated sewage down them, so it flowed straight to the sea.