Asia’s Sinking Cities

“Sinking Cities, Rising Seas” is a paper was published just ahead of the United Nations’ Intergovernmental Panel on Climate Change.  The paper comments on how the world must work together to limit the rise in global temperatures to 1.5 degrees Celsius above pre-industrial levels in order to stave off certain climate catastrophe.

If not limited, sea levels could rise as much as 40 centimetres — nearly 16 inches — in the coming decades and a 2 degree Celsius rise in global warming “would take us into a climate regime unparalleled in human history.”

High-risk sinking cities are collectively home to over 83 million people. This number is sure to grow exponentially as global urban centres continue to burst from their seams.

Asia has experienced — and will continue to experience — the most rapid urban growth. Currently, 54 percent of the Asian population resides in low-lying, storm-prone coastal areas.

Case studies in the report have heightened “overall vulnerability to sea level rise and to damaging storm surges”. Some cities, such as Jakarta, have lost their valuable natural means of flood protection to rampant development. Additional factors like poor planning exacerbate an already dire situation while “climate change acts as a further multiplier of existing and future vulnerabilities.”

Here’s a look at the Asian cities spotlighted in “Sinking Cities, Rising Seas” with info on why they’re sinking, what’s at stake and how they’ve taken action if at all.

Jakarta

A giant sea wall is used as a barrier to prevent sea water from flowing into land and cause flooding in Jakarta. (AP photo)

The Indonesian capital of Jakarta holds the dubious distinction as the fastest sinking city in the world at a clip of roughly 10 inches per year. About 40 percent of the sprawling city now lies below sea level per the report.

The main reason this city of nearly 10 million is sinking — and sinking so fast — is relatively straightforward: the absence of a reliable network of piped-in water has led to a preponderance of illegal private wells used by Jakarta residents to extract groundwater.

And that’s not the only issue. Jakarta’s soaring skyline packed-full of hulking, high-rise buildings is further squashing the city while the loss of groundwater undermines Jakarta from underneath, the sheer weight of its buildings pushes from above, causing further sinking.

Indonesia’s president says he wants to see the speedy construction of a giant sea wall around Jakarta to prevent the low-lying capital from sinking under the sea.  His government is up against a tight timetable, including a forecast by experts that at the current rate, one-third of Jakarta could be submerged by 2050.

He also has other ambitious plans for Jakarta, a congested, polluted and sprawling metropolis of 10 million. He wants to build a new capital, suggesting it should be outside Indonesia’s main island of Java, where 57 percent of the country’s nearly 270 million people are concentrated.

“We want to separate the capital, the centre of government and Jakarta as a business and economic centre,” he said.  Jakarta’s vulnerability to flooding and earthquakes is also a factor, Widodo said. “We need to make sure our capital is safe from disasters,” he said, without naming the location for the new capital.

Bangkok

Asia’s Sinking Cities

With an elevation that reaches just five feet above sea level, governmental officials estimated in 2015 that the Thai capital, which is sinking at a little under an inch per year, could be submerged within 15 years if the water around the city doesn’t cease rising at the current rate.

While subsidence caused by groundwater extraction is less an issue than it once was in Bangkok, the ground beneath the city is essentially caving in under the substantial heft of its cloud-brushing built environment. 

Bangkok’s sinking feeling has ironically been made worse by its reaching for the skies. The sheer weight of its buildings is pressing into the riparian sediments and compacting them as the sustaining water is depleted from them,

Thailand’s National Reform Council  recommended building a massive seawall around the city, there are more than 700 building with more than 20 floors spread out across Bangkok and more than 4,000 buildings with between eight and 20 stories.

Shanghai

Image result for shanghaI sinking

Like many other sinking cities that are particularly vulnerable to the effects of climate change, Shanghai, the world’s most populous city, is sinking under the weight of its own development. This has been made worse by groundwater extraction. Per the report, the total losses resulting from the structural havoc that subsidence has wreaked on Shanghai’s buildings and infrastructure was roughly $2 billion from 2001 through 2010.

Shanghai, however, has demonstrated that aggressive schemes to slow subsidence have proven effective. Restrictions on private wells, a GPS system to better monitor the sinking and a larger shift away from groundwater extraction have helped to slow the city’s annual sinking rate from 3.5 inches to less than half an inch.

What’s more, an effort to pump billions of gallons of water into once tapped-out aquifers hasn’t just slowed but even reversed sinking in some areas.

ManilaT

Asia’s Sinking Cities

he Philippine capital of Manila is chaotic, vibrant and impossibly dense. It’s also a verified fast-sinker at roughly 4 inches per year — that’s 10 times the rate of sea level rise caused by global warming.

Groundwater extraction is again the main culprit here.  As the city has an average elevation of around 5 metres [16 feet], it seems to be living on borrowed time. The subsidence not only increases the absolute risk of flood, but also the areas affected: high tides can penetrate further inland and floods may recede more slowly. This means that there is increased risk of salination of soils that were previously fertile.

Water-intensive rice production just north of the city and illegal, flood-causing expansion of agricultural fishponds aren’t helping matters.

Dhaka

Asia’s Sinking Cities

Described as “another low-lying, river-side city beset by a sinking feeling caused by unsustainable extraction of groundwater,” the Bangladeshi capital city of Dhaka is sinking at a rate of a little over a half-inch per year. Shifting tectonic plates play a hand in the subsidence experienced in the region although groundwater extraction is the primary cause.

Although Dhaka’s sink rate isn’t as alarmingly fast as in some other cities, the overall situation is made exponentially worse by the fact that sea level rise in the Bay of Bengal is 10 times the global average. This has caused millions of people in low-lying coastal areas southwest of the city to migrate en masse to Dhaka’s already overstuffed slums.

To their credit, city officials have undertaken some efforts to lessen the deadly impact of flood-producing weather events.