Climate change is the most determinant change factor of our time and cities must play a central part in addressing it.
Climate change is the most determinant change factor of our time and cities must play a central part in addressing it. Cities are compelled to do so because the effects of climate change, which include rising sea levels, an increased frequency and severity of storms, precipitations, floods, droughts, hurricanes, heat waves and other extreme weather events would be for the most part felt by people living in urban areas; and because they produce ¾ of green house gas (GHG) emissions globally.
Building resilience in urban planning
Building resilience depends on the capacity to anticipate and plan for the future. The continued implementation of a plan that anticipates the effects of future shocks can help a city withstand them and rebuild itself when necessary.
Resilience is not an add-on but an integral part of a city’s plan
Hence, resilience is greatly influenced by the quality of local management, its capacity to anticipate and enforce, the availability of information and the quality of the infrastructure and services that the city provides.
Resilience is not an add-on but an integral part of a city’s plan. It can only be achieved if all components of the complex urban system are taken into consideration. Therefore, instead of seeing vulnerability as an additional concern to be address with stand-alone efforts, cities will benefit from better integrating resilience into urban planning.
A resilient city is competitive and can sustain its advantage over time. By proactively increasing resilience, cities will be better positioned to absorb and respond to shocks. The primary purpose of urban investment is to enhance the functioning and performance of the relevant urban area. New investment for resilience will be more attractive for investors as it mitigates risk and enhances reliability of system performance. Resilience investments should aim to create a development premium for an urban area.
the cost of Hurricane Katrina … was estimated at USD 100 billion.
Inaction is expensive. Cities that have not been able to prepare themselves for the effects of extreme weather events have suffered severe disruption which will take decades to overcome. In the absence of action, the expected costs are high. The cost of Hurricane Katrina on New Orleans and other affected areas was estimated at USD 100 billion. In Manila, Bangkok, and Ho Chi Minh City, costs of damage from climate change-related flooding are likely to be substantial, ranging from 2 to 6% of regional GDP.
Adapt to reduce vulnerability
In addition to loss of life, extreme weather events cause major damage to property and infrastructure, resulting in massive economic and productivity losses. The estimates of sea level rise for this century vary between 18 cm and 2 metres, with cities such as Kolkata, Mumbai, Dhaka, Guangzhou and Ho Chi Minh City among the most affected. Much of Singapore’s city centre is built on reclaimed land and would be affected by sea level rise putting the financial district and other multi-million infrastructural investments at risk.
Vulnerable areas should be demarcated according to risk levels
Planning standards mainstream risk reduction into urban development. Vulnerable areas should be demarcated according to risk levels, for instance areas exposed to annual flooding, areas exposed to flooding once every 10 years and so on. Land use and building standards should be adjusted to each of those areas.
For instance, areas exposed to regular flooding should be left vacant or reserved for parks and sport facilities; trees and vegetation should be protected to sponge up water excess and prevent occupation. Building requirements in areas exposed to periodic flooding can include banning residential uses on ground floors and construction over pillars. Capacity building of planning staff and ongoing training for local builders and contractors, including informal ones, should be promoted. In Durban, the Municipal Adaptation Plan (MAP) incorporates climate change adaptation across departments in municipal day to day operations, planning and decision making.
Planning should guide development to non-vulnerable areas. Urban settlements often develop in hazardous areas due to a lack of land in safer locations. Unaffordable land leaves no alternative to the poor but to settle next to jobs and transportation nodes irrespective of how hazardous the site may be. Planning can guide growth away from high risk sites such as flood plains, areas affected by sea level rise and drought areas and encourage it there where it is safe. The layout of trunk infrastructure and rights-of-way, and public transportation networks are major tools for achieving this.
Infrastructure location and construction standards must be adapted to local risk factors so that roads, bridges, power lines and pipes can cope with extreme weather events. Adaptation cannot be separated from basic infrastructure deficits in drainage, water supply and sanitation. Heavy rains that would be channelled away causing no damage in one city can be devastating in informal areas lacking adequate drainage or where the system is clogged and not properly maintained. Potable water shortages can become more serious in contexts of substandard supply and contribute to spreading diseases.
Heavy rains that would be channelled away causing no damage in one city can be devastating in informal areas lacking adequate drainage
Most coastal zone related measures have centred on tackling floods through hard infrastructure. Regulating land use according to risk assessments is a proactive measure that can complement and improve the efficiency of such investments. Dhaka has reinforced river and canal embankments and built protective walls, sluice gates, and pumping stations, but also worked on addressing encroachment on several city canals which has reduced canal-filling and drain-clogging. The programme has proved effective in protecting over 50% of the city from major floods in 1998 and 2004. Singapore’s buffer zone development requires new land reclamations to be 2.25 metres above the highest recorded tide level.
Take advantage of climate change mitigation opportunities at the local level
Efforts to reduce emissions start with knowing how they are produced. An inventory allows a city to quantify its emissions, providing policy makers with a baseline and identifying reduction opportunities. It is important to set a clearly quantified GHG reduction target; most cities have established these as a percentage of improvement compared to the baseline year.
Emission reduction should be embedded in spatial and transport planning. Lower density development occupies more land, resulting in loss of forest and vegetation. This reduces nature’s CO2 uptake capacity. Compact city policies rationalise the use of land which creates opportunities for making compatible growth and the retention of open areas. Mixed-use reduces the need to travel, and if public transport could provide a time and cost advantage over private cars, car ownership would be dissuaded, reducing emissions.
Buildings consume about one third of energy worldwide throughout their life-cycle. Rapid population growth is expected to lead to an increase in the building stock, which under the “business as usual” model will entail a greater energy demand. Building regulations at the local level aimed at energy efficiency can contribute to reduce consumption and GHG emissions.
Industry can generate up half of a city’s total emissions. Although some industries have invested in energy efficiency and offsetting technology, it is still an energy intensive sector and can be extremely polluting.
Waste can generate up to one forth of emissions, the bulk of these stemming from burning of waste and disposal in uncontrolled sites. Waste generates 11% of total emissions in Mexico City, 20% in Bangkok and about 25% in Sao Paulo.
Urban greening, through projects such as tree-planting schemes and green roofs, can improve air quality and reduce the heat island effect.
Urban greening, through projects such as tree-planting schemes and green roofs, can improve air quality and reduce the heat island effect. In the US, carbon sequestration – the capture and storage of carbon – in forests has been estimated at between 1.5 and 6.5 metric tons of CO2 per hectare. However, even after saturation, trees would need to be sustained to maintain the accumulated carbon and prevent its release back in the atmosphere.
Captured methane in sanitary landfills can be used as an energy source to produce heat and hot water. The city of Lille reuses methane extracted from its municipal landfill for fuelling a share of its public bus fleet. Methane from Sao Paulo’s Bandeirantes plant generates 7% of the city’s electricity consumption, enough to supply a population of 600,000 for 10 years. The Okhla composting project in Delhi reduces around 1,600 tonnes of methane emissions per year which is equivalent to 34,000 tonnes of CO2.
Adapted from Urban Planning for City Leaders published by UN-HABITAT. Lead author: Pablo Vaggione
Original Link: Building Resilience And Reducing Climate Risks In Cities