Wednesday, September 7, 2005

When the Levee Breaks

When the levee breaks 
Ian Christie 
Sept. 6, 2005 
Read the entire article at:
The New Orleans disaster should inundate the rich world’s political imagination with awareness of man-made climate change, says Ian Christie.

The drowning of New Orleans is a disaster that will scar bodies, minds and landscape for many years to come.

Like the Asian tsunami of December 2004, it has transfixed the attention of people all over the world.

And like the tsunami, it seems to be a portent for those hundreds of millions who live on the shorelines of the Earth.

It could be that the "Big Easy" is the first of the world's cities to be wrecked by man-made climate change.

Whether or not climate change is a key factor, the magnitude of the two disasters is such that they might just be what it takes to break down the mental "levees" that have prevented leading politicians from facing up to the risks from climate change.

In particular, New Orleans could be a decisive symbol of unsustainable hubris: built below sea level, next to a "dead zone" of nitrate pollution from the Mississippi river, and looking out on to a seascape of wrecked oil rigs.

Heedless over-development of wetlands, reliance on fossil fuels from risky places, diffuse pollution on a vast scale -- all the United States's (and many others') ecological sins and blindspots are on display.

The hurricane system in the Caribbean and Gulf of Mexico may not yet be directly affected by global warming -- there is plenty of evidence for half-century cycles of activity that account for the special severity of recent storms.

But models of climate change show that warming will probably lead to more severe and frequent storms along with sea-level rise.

The tsunami highlighted the vulnerability of big cities and commercial developments that have grown on the coastlines of south Asia and have removed the natural sea defences provided by mangrove swamps.

The New Orleans catastrophe provides warning of what to expect on a far wider scale if climate change proves to be as serious as most climate scientists now fear.

The bulk of the world's population lives on or near coasts.

The largest cities tend to be at the mouth of big rivers and close to sea level.

This presents major risks even for those cities not in the line of fire from hurricanes or tsunamis induced by earthquakes.

Sea-level rise poses mounting dangers to great cities such as Venice (notoriously vulnerable to flood and decay, and human loss) and Shanghai (which is beginning to sink into its foundations).

Development in heavily populated deltas, such as extraction of fresh water, leads to land sinking at a faster rate than sea-level rise.

No less threatening than storm surges and the breakdown of sea defences, is the insidious risk of salt intrusion into water tables.

As urban populations demand more fresh water and global warming alters rainfall patterns, so water tables will sink and salt water will invade the aquifers on which cities depend.

Dependence on groundwater is all the greater given the high level of pollution in big cities' rivers and lakes, so the damage done by salt intrusion over the long term could be fatal to large areas of many cities.

Salt water has already penetrated 5km below Manila as its water table falls.

Here the TV images are even more powerful, coming as they do from the heart of the USA.

And fierce debate over the relief effort, the stranding of poor blacks in danger and squalor in the city centre, and the maintenance of the levees, has begun to make connections between the specific case of New Orleans and the wider politics and culture of the USA and the rich world.

This is clear in the heartsearching the hurricane has prompted about racial division in American cities.

The next connection to be made is with global warming and the urgent need to adapt -- and also to reduce risk by cutting carbon emissions fast.

On the west coast, the California governor Arnold Schwarzenegger is breaking ranks with his fellow-Republican president on energy and climate policy, and cities across the USA are signing up to carbon emission cuts.

Summarized by Copernic Summarizer


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