*A man watches as an army helicopter drops water on burning houses in a neighbourhood of New Orleans during Hurricane Katrina, 4 September 2005*

By Wilson da Silva

BODIES FLOATING along flooded streets, cities abandoned, overwhelmed police leaving their posts and committing suicide. It’s a nightmare scenario none of us expect to see in real life; and yet one that played across our television screens and filled our newspapers for weeks in September.

The fall of New Orleans – and the wave of destruction that accompanied it along the Gulf Coast of the United States – has been as spectacular as it has been frightening. Once again, Nature has reminded humanity of her power, smashing buildings as if they were made of matchsticks, and bringing once-proud cities to their knees. Within days.

Last month, Cosmos published a special 25-page report dedicated to the topic of climate change (“Goodbye Earth? The truth about climate change”). In it, we stated that climate change would inevitably trigger storms that were increasingly violent, that these would become more common as well as more intense; and that, as a result, within 25 years we would likely see cities fall and thousands of people perish.

At the time of writing, it seemed unreal to talk about the toppling of modern cities. Although our series was based on the best science available, the kind of future it forecast seemed bleak, strange and unbelievable.

No longer. When that issue hit the newsstands, I was attending a conference of the Science Communicators Association of New Zealand in Wellington – the same day that Hurricane Katrina descended on the Gulf Coast. Over the days that followed, I read with rising incredulity of the devastation of New Orleans, and official calls to abandon the city.

The fall of New Orleans is a warning: it shows us how quickly our proud cities – seemingly powerful and resilient – can buckle in the face of Nature’s onslaught. How quickly our technologies fail, and our intricate networks and vast resources can nevertheless be overwhelmed.

If such instant destruction can happen to one iconic city in the world’s most powerful nation, what of the hundreds of cities that may be battered – again and again – as freakish weather becomes commonplace and storms more violent? Are we really ready for the world of 2030?

We may not be able to blame Hurricane Katrina on global warming: experts say it is impossible to determine if any one storm is attributable to the greenhouse effect. But, while the number of tropical cyclones and hurricanes worldwide has so far remained stable – at about 90 a year – research indicates they are becoming stronger.

Kerry Emanuel, a leading U.S. hurricane researcher at the Massachusetts Institute of Technology in Boston, has shown that the intensity of hurricanes – both in terms of wind speed and duration – has risen by about 70 per cent in the past 30 years.

Many consider Hurricane Katrina a portent of what is to come, among them the European Commission and the World Bank. Even Sweden’s King Carl XVI Gustaf was moved to say, “It is quite clear that the world’s climate is changing, and we should take note. The hurricane catastrophe in the United States should be a wake-up call for all of us.”

Wilson da Silva

OPINION | The Fall of New Orleans