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Defining Resiliency

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Key characteristics of a resilient city include:

  • Spare capacity - When a key system fails or a vital resource is lost, what backups and alternatives exist?
  • Flexibility - How strong is the city's ability to evolve and adapt to changing climate conditions and extreme weather events?
  • Limited or 'safe' failure - When a system component fails, can it be contained or could its effects spill over into other areas, potentially causing a cascade of more serious problems.
  • Rapid rebound – How quickly and how fully can functions be re-established after a disruption?

A report from CDP Cities has found that actions to mitigate or adapt to the effects of climate change are not only helping to slow the growth of greenhouse gas (GHG) emissions, but are also contributing to the health and wealth of cities. Cities that show strong engagement on climate change are "saving money, creating more attractive investment environments, and enabling citizens to live healthier lives".

To combat climate change, cities are redefining resilience with a multi-faceted strategy. On the one hand, they must build up defences against rising sea levels but, on the other, they recognise that old approaches won’t work forever.

For example, the Netherlands, with 60% of its land below sea level, has held back the sea for centuries with dikes, dams, locks and storm surge barriers. It is the site of ‘Delta Works’, the most extensive flood management system in the world. However, new strategies are being considered. Areas prone to flooding have been vacated or turned into parkland, while water is being reintroduced to some areas to improve plant and animal diversity.

Natural disasters have affected an average of 220 million people per year over the last two decades, according to the United Nations Development Programme (UNDP). The UNDP spends around US$150 million every year to improve resilience in developing countries and notes that the loss of life is concentrated in such countries due to a lack of resources. But if the toll on human lives is highest in emerging countries, the bulk of property damage is in established cities.

Flooding is one of the biggest concerns, with flood-related costs increasing at a rapid rate. By 2050, the cost of urban flooding could reach US$1 trillion if no adaptive measures are taken – even if steps are taken, the costs may reach US$60 billion.

"The rate of sea-level rise appears to be accelerating, and while the impact of that is uncertain we know it will be significant," McIlwain said. "Meanwhile, after decades of planning, almost all American cities are still in the preliminary stages of managing climate impacts. The economic and political cost of reshaping a city is too steep".

But, the cost of doing nothing will be even steeper. While it’s unfeasible to move Manhattan buildings onto higher ground, New York has pursued a US$20 billion to reinforce existing sea walls and expand surge barriers. One of the most ambitious suggestions was a proposed 4,800 foot movable sea wall stretching between Brooklyn and Staten Island at a cost of US$6.5 billion.

However, many other plans have moved forward, with government grants having helped owners to make flood-resistant infrastructure improvements and governments passing measures to adapt building codes in flood-threatened areas. An ‘Office of Resiliency’ was also created to coordinate adaptation actions across multiple agencies, while design competitions were held to find creative ways to fortify vulnerable areas.

Originally published : November 2013

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