Monday, 11 February 2013

Breathless in Bombay

Slum housing along the perimeter fence of Mumbai Airport
Most people would associate marine science with the bracing sea air and sound of the wind and sea. It is getting increasingly hard to find anywhere remote from the imprint of humanity and when an attractive place is ‘discovered’ and gets into a travel guide, the visitors soon begin to roll in. So much effort is placed on the ‘remote’ or ‘pristine’ that it is easy to ignore the other end of the spectrum; the coastal megacities where a quarter of a billion people live. Recently, I was sharply reminded of this when my plane landed in Mumbai on a hazy day and I felt my lungs filling with the acrid air of this city of over 18 million people. India’s increasing prosperity, like China’s, is putting a lot of pressure on the environment.

Last month, I was part of a group of 17 co-authors of a paper examining this issue and titled Megacities and Large Urban Agglomerations in the Coastal Zone: Interactions Between Atmosphere, Land, and Marine Ecosystems. My interest in mega-cities was a very practical one because I spent some years living in them. In 1987 I did a routine medical when I left Mexico City after living there for about three years. The doctor showed me the striations on my chest x-ray that were typical of a heavy smoker. “But I don’t smoke” I protested. “I know, but I do,” he said with a sheepish smile. “Imagine what mine look like!”  Six years later, I moved to Istanbul at a time when massive amounts of lignite were burned to keep the apartment blocks and houses warm in the winter. The air was full of yellow fumes made worse by the heavy traffic and there were few days when I didn’t wake up with a headache. But then the city switched to gas and things dramatically improved and serious efforts began to curb the millions of tons of raw sewage discharged to the Bosporus, the vital connection between the Mediterranean and the Black Sea.

But the issues of such dense human agglomerations go far beyond the problems that can be fixed by means of simple engineering. As we demonstrate in our paper, the cities act as heat islands and change the flow of air between land and sea, transporting pollution for tens to hundreds of kilometres over the ocean. They have strong influences over overfishing, harmful algal blooms, eutrophication (the over-fertilisation of the sea) and cause feedbacks to the atmosphere via marine emissions. So far, as scientists we have been unable to keep pace with the rapidly developing and complex array of problems. Our paper suggests a strategy for how some of the poorly researched issues can be tackled and hopefully serves as wake-up call. Already 16% of the world’s population lives in cities of more than 5 million people (the population of Norway or Scotland) and they place a huge resource demand on surrounding areas, also separating people from their natural environment and making it more difficult to instil a caring attitude towards it from an early age. Reconnecting people with their environment is a huge task that parallels the need to study and solve the problems technologically, for if there is no willingness to pay the costs, nothing will change.

Further information
Roland von Glasgow et al (2013) Megacities and Large Urban Agglomerations in Coastal Zones: Interactions Between Atmosphere, Land, and Marine Ecosystems. AMBIO 42: 13-28

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