Det er Sydkinas største by, Guangzhou (Canton), 120 km nord-nordvest for Hong Kong med nu 13 mio. indbyggere i stor-Canton, men også byer i USA, Bangladesh, Ecuador, Elfenbenskysten, Indien, Indonesien og Vietnam er i farezonen, fremgår det af nyt studie.
WASHINGTON DC, 19 August 2013 (World Bank): Climate change, rapid urbanization, and subsiding (synkende) land are putting the world’s coastal cities at increasing risk of dangerous and costly flooding, a new study calculating future urban losses from flooding shows.
The study (link neden for) led by World Bank economist Stephane Hallegatte and the OECD, forecasts that average global flood losses will multiply from 6 billion US dollar per city in 2005 to 52 billion a year by 2050 with just social-economic factors, such as increasing population and property value, taken into account.
Add in the risks from sea-level rise and sinking land, and global flood damage could cost 1 trillion dollar a year if cities do not take steps to adapt.
Most coastal cities’ current defenses against storm surges and flooding are designed to withstand only current conditions.
They are not prepared for the rising sea levels accompanying climate change that will make future floods more devastating, the authors write. Protecting these cities in the future will take substantial investment in structural defenses, as well as better planning, they write.
The findings add to a series of recent studies, led by the World Bank’s “Turn Down the Heat” reports, that have looked closely at expected rises in sea level and their impact on vulnerable regions around the world.
Who is most at risk?
The new study, part of an ongoing OECD project, examined maps and databases of population and world assets, flood-prone (udsatte) regions, storm frequency data, and cost of damage models for 136 large coastal cities.
For the first time, it took into account existing coastal defenses and their level of protection.
In terms of the overall cost of damage, the cities at the greatest risk are:
1) Guangzhou (China), (http://en.wikipedia.org/wiki/Guangzhou)
2) Miami,
3) New York,
4) New Orleans,
5) Mumbai (Bombay),
6) Nagoya (Japan),
7) Tampa,
8) Boston,
9) Shenzen (China), and
10) Osaka (Japan).
The top four cities alone account for 43 per cent of the forecast total global losses.
However, developing-country cities move up the list when flood costs are measured as a percentage of city gross domestic product (GDP).
Many of them are growing rapidly, have large populations, are poor, and are exposed to tropical storms and sinking land.
The study lists the 10 most vulnerable cities when measured as percentage of GDP as:
1) Guangzhou, China;
2) New Orleans, United States;
3) Guayaquil, Ecuador;
4) Ho Chi Minh City (Saigon), Vietnam;
5) Abidjan, Ivory Coast;
6) Zhanjing, China;
7) Mumbai, India;
8) Khulna, Bangladesh;
9) Palembang, Indonesia; and
10) Shenzen, China.
In most of these cities, the poor are most at risk as rapid urbanization has pushed them into the most vulnerable neighborhoods, often in low-lying areas and along waterways prone to flooding.
Taking action now
Læs videre på
http://www.worldbank.org/en/news/feature/2013/08/19/coastal-cities-at-highest-risk-floods
Man kan se yderligere omtale af studiet på
http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1979.html
