Complex and fixed nature of urban infrastructure

2.1 Complex and fixed nature of urban infrastructure

Urban areas’ dependency on complicated and extensive networks for transportation, communication and trade are a key factor in their vulnerability to climate impacts. Functioning urban infrastructure and a healthy environment not only provide the urban population with the necessary structure for carrying out economic and social activities, but are also prerequisites for ensuring the competitiveness of a city. Cities’ stability and prosperity rely on vast networks of provisional infrastructure – solid waste disposal; wastewater treatment; transportation; water, energy and sanitary provisional systems. However, environmental impacts are dynamic. Not only do they often exhibit non-linear and cumulative effects, but they have sustainability thresholds and involve irreversibilities (OECD, 2008b). Disruptions in infrastructure systems create inefficiencies and slow down economic progress, imposing costs on the local and national economy.

Physical infrastructure, such as transportation, energy and communications infrastructure, and social infrastructure, such as health, governmental and educational services, are strongly interdependent in urban areas (Hitchcock, 2009), and vulnerable to the non-linear disruptive effects that can result when critical temperature, wind or water exposure thresholds are surpassed. For example, large portions of mass transportation systems and road networks, which are critical to cities’ productivity, communication and competitiveness, can be cut off or shut down due to flooding in key locations (Box 2.1). Urban infrastructure is not typically designed to handle extreme events, particularly in developing countries. Temperature extremes and less predictable precipitation cycles will likely require key infrastructure (e.g. for energy production or transport) to be replaced or repaired more frequently and may reduce their operational capacity (e.g. blackouts or service interruptions), if infrastructure design does not take potential

climate variations into account (OECD, 2009b). 9 Many of the dangers of climate change can be mitigated

9. Mansanet-Bataller et al, (2008) Cochran et al., (2009) in OECD (2009b).

by folding the expectation of a new climate into existing infrastructure development, although this is complicated by the dense interconnections among the infrastructures on which cities rely. It is also made more difficult by the tendency for the information most relevant for climate decision-making (e.g. impact of climate on local rainfall extremes) to be associated with the highest degree of uncertainty. Although urban infrastructure is an essential element in city competitiveness, cities in many parts of the world are struggling to meet the basic needs of their populations, and have limited resources to devote to adapting to climate (Ruth 2006, Ruth & Kirshen, 2006).

Box 2.1. Climate change, transportation and flood risk

The City of New York’s airports, as well as many of its power plants and waste transfer facilities, are at sea level and/or on waterfront sites. The subway system and subterranean water and sewer systems were designed for current sea levels. A Category III hurricane would flood all the tunnels leading out of New York, as well as the city’s airports, requiring the emergency evacuation of up to 3 million people (City of New York, 2007).

The Thames Barrier, which protects London from high seas, was raised only three times in its first six years of operation, but was been raised 56 times between 2001 and 2007. Flash floods caused approximately 600 flooding incidents in the London Underground between 1992 and 2003. A single 2002 flooding incident in the Borough of Camden caused traffic disruptions amounting to losses of at least GBP 100,000 per hour’s delay on each main road affected, without counting the costs of infrastructure damage. A recent report concluded that significant changes to current drainage systems would be needed to maintain current service levels in the event of even a small increase in storm rainfall. (Mayor of London, 2007).

Source: OECD (2008a), Competitive Cities and Climate Change: OECD Conference Proceedings, Milan, Italy, 9-10 October 2008, OECD, Paris.

Adaptation is also made difficult by the fact that modifications to urban infrastructure and the built environment are expensive and occur incrementally over long periods of time. For instance, transportation and flood control infrastructure can be built to withstand a wide range of extreme weather events, but such infrastructure generally lasts decades, heightening the need to incorporate extreme climate scenarios into current infrastructure design and planning. Vulnerability to storm and hurricane risks can be reduced through spatial planning and land management, but land-use changes occur over decades and urban buildings typically last 50 to 100 years, if not longer. As a consequence, urban adaptation options often must be anticipated by at least decades to be effective. Current adaptation efforts are challenged by the

uncertainty about the nature of future climate change impacts 10 especially given that adaptation costs are immediate while benefits are delayed and based on present assumptions of climate impacts (Hallegatte et

al., 2008). Adaptation to the most catastrophic events would require costly investments while running a strong risk of being unnecessary (Jones, 2004) at the least, and could potentially contribute to greater climate change damage by offering a false sense of security that puts larger population at risks if impacts exceed expectations (Nicholls et al., 2008).