Over the past half century, population growth has been a significant contributor to the increase in greenhouse gas emissions, but how will climate change impact urban populations living in coastal areas?
The Organization for Economic Cooperation and Development (OECD) released a study yesterday—December 4, 2007—that estimates the exposure of 136 of the world’s largest port cities to coastal flooding. The study concluded that the number of people in these 136 cities (each with a population of one million or higher) that are currently exposed to a 1 in 100-year coastal flood event will more than triple by 2070. At present, about 40 million people are at risk. By 2070, the number will rise to about 150 million due to the “combined effects of climate change (sea-level rise and increased storminess), subsidence, population growth and urbanization.” The OECD report also found that “asset exposure could grow even more dramatically,” reaching $35 trillion by the 2070s, “more than ten times current levels and rising to roughly 9% of projected global GDP.”
The report concluded that even if cities adopt high levels of protection in the future, “the large exposure in terms of population and assets is likely to translate into regular city-scale disasters across the global scale.” The report went on to say that, “The policy implications of this report are clear: the benefits of climate change policies – both global mitigation and local adaptation at the city-scale – are potentially great.”
So which cities and populations are most at risk?
By the 2070s, the top 10 cities in terms of population exposure (including all environmental and socioeconomic factors), are Kolkata, Mumbai, Dhaka, Guangzhou, Ho Chi Minh City, Shanghai, Bangkok, Rangoon, Miami and Hai Phòng. All the cities, except Miami, are in Asian developing countries. The top 10 cities in terms of assets exposed are Miami, Guangdong, Greater New York, Kolkata, Shanghai, Mumbai, Tianjin, Tokyo, Hong Kong, and Bangkok. Hence, cities in Asia, particularly those in China, India and Thailand, become even more dominant in terms of population and asset exposure, as a result of the rapid urbanisation and economic growth expected in
these countries.
Many smaller cities (both in terms of population and wealth) also experience very rapid increases in population and asset exposure. These include, for example, Mogadishu in Somalia and Luanda in Angola. While the absolute exposure of these cities is relatively low, the rapid increase expected by 2070s will nonetheless pose significant challenges for local communities.
