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Climate change adaptation - what the big cities are doing

Whilst reversing climate change is still a going concern, many scientists have resigned themselves to developing processes for adapting to the change. So what preparations are major cities with varying climates making?

London, UK

The key to London's climate-change adaptation lies in its defences against increases in flooding and temperature, which will affect all industries from finance to logistics.

London has become an 'urban heat island' it suffers from greater absorption of heat into building fabrics, which results in an intensified rise in temperature due to all the buildings, tarmac roads and people. New and existing buildings and infrastructure will need to be adapted to integrate low-carbon cooling methods to prevent the massive 5,900 heat-related deaths predicted by 2050.

A rising population means the London Underground will have to cope with up to 300,000 more passengers per day, so ventilation systems will need to be integrated into the already narrow tunnel structure to prevent rail buckling. By 2080 up to one and a half million properties will be at risk of flooding, and a seven-metre rise in the Thames would result in the loss of Canary Wharf, Chelsea and Westminster. London's competent Roman tidal estuary will protect London more effectively than any other city in the UK, but only if relevant upgrades and overtopping of walls are maintained.

Some 15 per cent of the city is on flood plains. To ensure it doesn't flood, all marshes must be used for storage, rivers must be deepened and widened, and oversized drainage systems integrated. To stop the 72 at-risk Tube and railway stations flooding, elevated rail lines should be incorporated into the network like those at London Bridge. To avoid the city's water supply becoming contaminated, sewers and culverts will need to be reengineered, costing a predicted £32,000 per property.

Shanghai, China

Shanghai has already begun to integrate emergency systems to combat climate change. A heat health-warning system has been developed using weather forecasts to predict irregular air masses attributed to heat death, and a Heatline call-out service has been introduced to assist elderly and vulnerable people during drastic rises in temperature.

Shanghai will see a rise in extreme events, such as floods, typhoons, droughts and landslides, and five months per year will exceed temperatures of 28°C. A seven-metre flood rise would cover most of the surrounding areas during wet seasons, majorly disrupting Shanghai's supply chain. Its current flood walls had an original lifespan of 1,000 years, but this has since been downgraded to only 100 years.

China's distribution network is predominantly above ground but authorities should consider moving it underground to avoid flooding during the wet months and evaporation during the hotter months. New buildings must also be built with better resilience to climate change: the current lifespan of a Chinese house is only 30 years.

Gaborone, Botswana

Botswana has little existing developed engineered infrastructure, networks and systems, leaving it most vulnerable to the ravages of climate change and least capable to adaptation.

For eight months of the year Botswana will suffer temperatures exceeding 28°C, which will impact heavily on agriculture and result in higher import rates. In contrast to other regions, which will experience higher levels of flooding, Botswana will fall victim to extreme droughts and increasingly unreliable rains, which will lead to desertification of the region.

To combat lack of water, supplies will have to be taken from groundwater sources and stored underground to reduce evaporation, and energy-free desalination using solar power must be integrated.

Schemes like the N-S Carrier Pipe connecting water from local regions should be continued. To reduce the need for cooling, street layouts and building orientation should be adjusted to encourage natural ventilation and self-cooling. Power generation should be decentralised, using dual-layer networks with lower voltage that can cope with minimal disruption. As the region has abundant coal deposits, small-scale carbon capture and storage systems could be exploited.

Rio de Janerio, Brazil

In recent years Brazil has improved its adaptation to climate change in relation to power generation and environmentally friendly living. The country generates more than 75 per cent of its electricity from hydroelectric power, and is second only to Japan in terms of recycling aluminium and plastics.

However, its adaptation to the impending floods, droughts and extreme temperatures faced by Rio de Janerio falls worryingly short; typhoons that were once believed a meteorological impossibility are now becoming a real threat. The unique geography of the area makes it prone to natural disasters. The Atlantic rainforest that once surrounded the elevated areas around the city has been stripped away, meaning Rio's capacity to absorb rainwater has been affected, compounded by its lowlying coastal marshes and lagoons being filled in by developers.

There is a government plan in place to urbanise Rio's most vulnerable sector of society, the hillside favelas, by 2020 but current measures such as concrete walkways have only hampered the favelas' ability to cope with flooding.

Sydney, Australia

Sydney is a city synonymous with hot summers and mild winters, seasonal characteristics that will only intensify due to climate change. Heatwaves and accompanying bush fires will become more commonplace, affecting all industries from transport to agriculture.

Sydney has already experienced rail lines buckling due to a rise in temperature. Research into developing crops with genetics suited to hotter and drier environments with higher carbon dioxide levels are being developed to encourage farmers to move to less fertile environments. The government has accepted that it must assume an important role in establishing the right conditions for communities and industry, facilitating their ability to adapt to climate change policy, including the improvement of land-use planning, codes and standards or environmental or public health legislation.

Ensuring the sustainability of protected natural environments such as the Great Barrier Reef and the Murray-Darling Basin features high on Australia's agenda. For the latter, irrigation systems will be improved and new water will be put back into the basin to address evaporation concerns.

Water shortage will be a major concern, so the Bureau of Meteorology is researching ways to improve current water quality. A robust water market and trade environment is also being developed to deliver water to areas of high priority, and alternative water supplies in remote cities and towns are under consideration for investment.

New York, US

Hurricane Sandy has demonstrated to the rest of the world New York City's less-than-adequate flood defences. These must be improved as the likelihood is that the frequency of these extreme events is set to increase.

It is estimated that annual precipitation will increase by 5 per cent by the 2020s and up to 10 per cent by the 2050s. Rapid ice-melting due to climate change suggests sea levels could rise by approximately 104cm by the 2080s, causing increased flooding like that seen in Wall Street area of New York this autumn.

A large area of New York lies less that 10ft above sea level, meaning storm-related coastal flooding due to sea level rise is likely to increase which will interact with the other stresses that the city faces such as the population and accompanying pollution grows. This will affect the city's plans for coastal waterfront development, leading to enhanced flooding of low-lying neighbourhoods and infrastructure, threats to consistent delivery of water supplies and the risk of increased structural damage.

To overcome this, New York must recalibrate built-environment design standards to include climate-change projections. One viable solution to preventing future flooding on the scale of Hurricane Sandy would be to integrate flood defences like those seen in Scandinavia, using a complex system of locks and dams to protect parts of the city's low-lying coastal areas. 

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