Are we approaching a decade of ‘the wrong sort of water’? While rising sea levels threaten some the world’s largest cities, freshwater shortages could increase water stress. South Asia in particular may face the worst of both.
Sea levels are rising at an accelerating rate
According to the Intergovernmental Panel on Climate Change, seas will rise 84 centimetres by the end of this century, a change that will be accompanied by stronger and wetter hurricanes (due to higher temperatures) and fewer fish (due to acidification). Seas are currently rising by 3.7mm per year, which is 2.5x faster than the rate from 1900 to 1990.
The unwanted coastal view
8 of the 10 largest global cities are near the coast, according to UN data. By 2050, the homes of at least 300mn people will flood annually, according to Nature Communications (up from a previous estimate of 80mn), including 100mn people in China, 42mn in Bangladesh, 35mn in India and 23mn in Indonesia. A worst-case scenario could see 640mn people affected by 2100.
Sea defences are expensive and could prove futile
Singapore recently announced a US$72bn programme to protect itself from rising sea levels over the next the next century, via sea defences, and by building on higher ground (eg Changi Airport’s newest terminal is being built at a height of 5.5m above sea level). Like other island nations, the country does not face any easy alternative courses of action if sea levels continue to rise.
Moving people inland is disruptive, and not always possible
In a contrasting approach, and despite approving a US$40bn defensive seawall project, Indonesia has chosen to move its nation’s political capital from Jakarta to a new location in East Kalimantan, Borneo. Jakarta is one of the fastest-sinking cities globally, partly due to unregulated water extraction. Rising ocean water levels are compounding the issue. But actually moving a city of 10mn inhabitants in its entirety 1,300km to a different island is not going to happen: it will be too costly at various levels, economically, environmentally and socially.
Investors are underpricing climate change risks
A previous World Bank study had estimated US$11tn annual costs from higher sea levels by 2050. However, given recent changes in our understanding of the pace and severity of climate change, these estimates could prove conservative. For example, flooding in US coastal communities is 3-9x more frequent than it was just 50 years ago; 40% of the US population live in such communities. Low-lying emerging economies, such as Bangladesh, are likely to be much more affected, given weaker physical infrastructure and a likely increase in the severity and frequency of flooding incidents.