Climate change poses grave danger to MUMBAI city

Mumbai: Climate change and reckless development are leaving Mumbai increasingly vulnerable to the elements. A news report on an ongoing climate study places India's financial capital sixth in alist of 20 port cities worldwide that are at risk from severe  storm-surge flooding, damage from high storm winds and rising seas. By 2070, according to the study, an estimated 11.4 million people and assets worth $1.6 trillion would be at peril in Mumbai due to climatic extremes.      The in-progress study, by Organisation for Economic Co-operation and Development (OECD), reveals that many of the susceptible port cities are in Asia. In the news report's list—ranked by assets at risk—eight among the top 10 fall in the world's most populous continent. Poor planning increases climate risk to Mumbai Experts Seek Reduced Concretisation And Drainage System Revamp; BMC Says Work Is Underway On Storm Water Project      Climate change is putting millions of lives and assets worth billions in port cities at increasing risk, reveals a study by Organisation for Economic Cooperation and Development (OECD). Among the 20 port cities whose assets are in danger from climate extremes is Kolkata which, according to a news report, stands in the fourth spot. In the City of Joy, 14 million citizens and assets worth $2 trillion will be at peril by 2070.      Experts assert that rampant concretization in global cities is not only leading to fluctuations in temperatures worldwide but also causing shifts in microclimates. These changes together are likely to build up into disastrous scenarios by 2070, effecting excessive rainfall. In cities like Mumbai, where poor planning has left little space for water to percolate into the ground, the impact may be severe.      "A big portion of Mumbai is concretized and this is increasing. Solar radiation is absorbed by concrete, triggering urban heat island effect, where temperature within the city rises. The circulation of warm air from the city with cooler air currents from less urbanized areas can cause extreme weather conditions," says Subimal Ghosh, an associate professor in the civil engineering department of IIT-Bombay.      Ghosh had contributed to an OECD study in 2010 on flood risks, climate change and adaptation in Mumbai. That report predicts an increase in the intensity of the Asian summer monsoon. It foretells a 3.6 degrees Celsius increase in the mean temperature in Mumbai by 2070 or 2080. "This is the worst-case scenario. Even if not so high, the mean temperature will rise significantly. Another preliminary research by IITBombay too shows that heat waves will be warmer by about 2degrees Celsius," Ghosh says.      According to the 2010 study, human heedlessness is as much a cause of Mumbai's susceptibility to flooding as its geographical location. The city's concretization has reduced the possibility of rainwater getting absorbed into earth and its high population density has put additional strain on the creakingly old drainage system.      "Large areas of reclaimed land are situated just above sea level and below high-tide level. This inhibits natural runoff of surface water and impacts the complex network of drains, rivers, creeks and ponds that channel water into the sea. During high tide, seawater can enter the system, preventing drainage and, in extreme cases, lead to salt water deluge. The city's drainage system is inadequate to cope with heavy rainfall and is impeded by urban encroachment," the 2010 study explains.      Rakesh Kumar, head of National Environmental Engineering Research Institute, also warns that "with very tall buildings around, sunlight will get blocked, causing humidity levels to rise, making the city a breeding ground for diseases".      The solution, most experts concur, lies in revamping the drainage system, among other steps. "We need to make sure that urbanization is allowed after careful planning and keeping in mind spatial distribution. Development needs to happen away from the city. Also, stronger weather forecast systems are needed and so are evacuation facilities for dwellers of low-lying areas," says Ghosh.