IF THE DOOMSAYERS of global warming are right and the water level rises by 3ft this century, our grandchildren may look back on Hurricane Katrina as an object lesson in how not to deal with the rising tide: how not to prepare for it, how not to respond to it, and how not to take adequate precautions against a repetition. Katrina was a disaster; the aftermath of Katrina has been a fiasco, and a cautionary tale.

This week British scientists gave warning that coastal areas face increased threat of flooding from high tides and changing weather patterns; but at the same time the Government is cutting back on flood defence spending. New Orleans may seem a long way away, but the storm surge that struck Louisiana on August 29 last year is the same water that laps our own shores, a little higher every year.

A year after Katrina, New Orleans remains submerged in bureaucracy, paralysed by failed politics, and alarmingly vulnerable. Much of the money needed to repair essential infrastructure has not yet materialised, and some $2 billion has vanished in fraud or waste. The city is operating on about one quarter of its pre-Katrina revenue because so many businesses remain closed and only half the city’s residents have returned.

My sister, who has lived in New Orleans for ten years, describes how her beloved home, once one of the most joyful places on Earth, has become a city under siege, climatically and mentally. Life in the Big Easy is hugely difficult. The suicide and murder rates are rising. One third of children have post-traumatic stress, and a further third show signs of depression. In some areas the jungle is growing back from the swamp, with creepers snaking into once-tended gardens, now abandoned. This summer, searchers found yet more bodies in wrecked homes.

For those who see their glass of mint julep half-full, there are a few reasons to be cheerful: most of the city’s 300,000 abandoned refrigerators have been removed; most houses now have gas and electricity, albeit intermittently; Antoine’s, the famous French Quarter restaurant, is open for business, although losing $5,000 a night. Some 45 million cubic yards of debris have been hauled away.

But no amount of optimism and sinew-stiffening mint julep can disguise the knowledge that hurricane season is here again. Repair work on the 150 miles of levees and floodwalls will not be completed for another four years. Even then, the defences may not be high or strong enough to protect the city against a Category 5 storm. New Orleans is so fragile today that another direct hit would wipe it off the map.

Katrina exposed rank inefficiency, some traditional corruption and an apparent lack of concern summed up in President Bush’s words to his emergency management director Michael Brown — “Brownie, you’re doing a heckuva job” — just before he was sacked. Above all, it exposed the disproportionate suffering of the poor and black residents of New Orleans, vividly reflected in Spike Lee’s angry new documentary, When the Levees Broke. Many blame the US Corps of Engineers for failing to design and maintain adequate defences. Those with longer memories blame the French for building a city on a swamp, much of it below sea level.

The excuses and recriminations will continue to ebb and flow. Guilt and innocence are never clearly defined in the vaporous atmosphere of New Orleans. What is inexcusable, amid the shifting responsibilities and accusations, is the failure to address with sufficient urgency how the city should be protected in the future.

Coastal marshlands to the south have always acted as a buffer, protecting the city against storms riding in from the Gulf of Mexico, but with rising water and more violent weather patterns, they are disappearing. In 24 hours, Hurricane Katrina destroyed wetlands that had been expected to last at least another half century. According to the US Geological Survey, some 500 square miles of marsh have vanished since 1980. These, more even than the strength of the levees, are what the future of New Orleans depends on, for without the barrier islands and coastal marsh, the city would be exposed to the ocean itself.

Re-establishing the coastal wetlands is an enormous ecological project, the “biggest, costliest restoration effort ever tried”, according to Fortune magazine, which estimates the cost at $14 billion. But it could be done, and unless it is, New Orleans will become an Atlantis, its fabled pleasures and beauties no more than aquatic legend.

In the wake of Katrina, the German Environment Minister enraged many in the US by saying: “The American President has closed his eyes to the economic and human damage that natural catastrophes such as Katrina — in other words, disasters caused by a lack of climate protection measures — can visit on his country.” President Bush has an opportunity to prove him wrong, defend New Orleans, dramatically improve race relations, take the environmental lead and protect a unique ecosystem — all at the cost of one twentieth of what has been spent so far on Iraq. There is little political will to do so. Since Katrina, the US Congress has not allocated a single dollar to restoring the wetlands.

The legend of Canute holds that the King, irritated by a flattering courtier’s claim that the great monarch could command the waves to turn back, made a point of planting his throne as the tide came in at Bosham to show that no man can control nature. This was a demonstration of humility, not arrogance, contrary to popular belief. Canute was right in the 11th century, but wrong in the 21st; we can hold back the tide and, as the waters rise at Bosham and New Orleans, we must.

New Orleans will not survive another Katrina, but given how little has been done to rebuild and defend the city in the last year, nor would President Bush. The residents of the Big Easy are not the only ones uneasily watching the weather forecast.

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