Sunday, November 24, 2013

Holding Back the Waves

Photo: Woman wading through flooded Venice plaza
One of the biggest environmental worries is the rising sea level which is now threatening many coastal cities. Across the globe the seas are rising up to meet us. A profoundly altered planet is what our fossil-fuel-driven civilization is creating, a planet where Katrina-scale flooding will become more common and more destructive for the world’s coastal regions. By releasing carbon dioxide and other heat-trapping gases into the atmosphere, we have warmed the Earth by more than a full degree Fahrenheit over the past century and raised sea level by about eight inches. Even if we stopped burning all fossil fuels tomorrow, the existing greenhouse gases would continue to warm the Earth for centuries. We have irreversibly committed future generations to a hotter world and rising seas.
The aftermath of Typhoon Haiyan, perhaps the most powerful storm on record to make landfall anywhere in the world, is a clear warning of the power of the weather and the elements to wreak havoc and destruction on us. The uncontrollable force of the environment attacking our cities is one of the most worrying threats facing the world, not least because, despite the immense danger it poses, there is little, in the short run, that we seem able to do to combat it. This will have huge consequences for our coastal cities. If we do not want the forced resettlement of millions, we are going to need some radical new solutions.
The UN’s Intergovernmental Panel on Climate Change has predicted a sea-level rise of between 18 and 59 meters by 2100. This could affect up to 634 million people who now live in low-lying coastal areas across the globe. More than 180 countries have populations in those zones, and two thirds of those have urban areas of more than five million people that are under threat.

Our usual response to threats of any kind is a demonstration of force and power. We fight attacks with weapons. We fight crime with police and harsh criminal punishments. You can therefore understand why we are stumped to find an immediate response to an environmental threat. Our natural reaction to any threat is to fight. But how do you fight wind and water?
Where our natural instinct is to do something bold, the argument of environmentalists that we should do the opposite – do less, make less, travel less, emit less – makes for hard reading. One  typical human response to rising sea levels and the threat of bigger storms and storm surges, has been to hold back the waves with hard engineering schemes made of concrete and steel. But flood defense barriers and storm drains do not come cheap and it is impossible to shore up thousands of kilometers of coastline globally.

So many coastal cities are going against the natural human grain and are increasingly turning to natural solutions, so-called soft engineering schemes, that redesign waterfronts to incorporate wetlands, oyster beds and other natural features. In New York, the emotional heartland of the skyscraper and of all things big, brash, steel and shiny, some scientists and engineers feel the soft approach to combating the elements might ironically be the most effective. Stephen Cassell is a New York architect who has designed an approach he hopes will influence town planning in New York. Rather than protect the city with hard defenses, his idea is to use nature to build its own protective barrier. If you build wetlands, beaches and marshes around the coastal regions, you are effectively building a sponge which not only absorbs the water but gradually lessens the impact of any waves of tidal attack on the city. A common rule of thumb, we are told, is that a wetland extending 14.5 kilometers out to sea will reduce the height of a storm surge by a meter.

The argument for the soft solution is not just about the effectiveness of the water barriers, it is also about the quality of life. You can walk on top of a concrete sea barrier but there is a limit to how enjoyable that is.  But if you build wetlands and beaches you introduce new wildlife and new environments which not only work to protect the city but improve the city as well. They offer people new things to enjoy and enhancements to their daily lives. It may not sound like a great rallying cry but it is heartening to know that brute force architecture can sometimes be beaten by pretty, sympathetic natural designs.

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