Climate Adaptation Begins with a Retreat
Published in The EarthSphere Blog. Cover Image: Cut and Run (modified from Google Maps)
Low lying areas of Indonesia are feeling the pinch of climate change and rising seas. Indonesia’s current capital city Jakarta is slipping below sea level and beset by a host of environmental problems. The government announced its long-range plan in 2019 for dealing with Jarkata’s issues — migrate and move to higher ground. Plans call for the government to move its operations to a new capital city named Nusantara. This migration could start as early as 2024.
Their new digs are in the province of East Kalimantan, about 700 miles northeast of Jakarta and on the other side of the Java Sea. Some confusion is inevitable since Nusantara is also the name applied to the Malay Archipelago, a region encompassing both Malaysia and Indonesia. Nusantara, Nusantara will be like describing New York, New York.
The move to terra firma should not come as a surprise since Jakarta is the fastest sinking city on the planet. This distinction as a leader in global inundation does not bode well for a long and happy future. Sections of North Jakarta subside at 25 centimeters a year. The irony of this situation is that the seawalls, designed to keep the city dry, are also subsiding at the same rate.
Jakarta’s Downward Spiral
Jakarta, situated on the northwest end of the elongated island of Java, has a metro-area population of 33 million people living at an average elevation of eight meters above sea level. But averages are deceiving since they simply even out the highs and lows. Currently, about 40 percent of Jakarta is below sea level.
Jakarta has the unwanted distinction of suffering from two anthropogenic effects — the ocean is rising, and the land is falling.
Climate change is driving a sea-level rise in two ways, both related to rising temperatures. A warming atmosphere encourages the melting of ice from glaciers and ice caps. But as the atmosphere warms, so do the oceans, leading to thermal expansion. Seawater, like most materials, expands as it heats up. Since the ocean basins have fixed boundaries, the only way seawater can expand is by rising higher. According to NASA, 38 percent of sea-level rise is from thermal expansion, and the remaining 62 percent is from meltwater.
However, human beings tend to exacerbate their problems through unintended consequences from their collective ignorance and indifference. The second of Jakarta’s problems is again man-made. Not only are its residents contributing to increasing ice melt as they burn fossil fuels, but they are also working hard to lower ground levels across the city. This self-induced ground subsidence allows them to sink beneath the sea much faster than the rest of the world. They accomplished this feat by pumping out groundwater.
Groundwater Woes and a Planned Retreat
Under normal conditions, rainwater sinks into the ground and replenishes underground aquifers, so water pumped out for human use is replaced by new rainwater sinking into the ground. We disrupt this healthy balance by pumping out more water than the rain can replace. Water residing in the rock and soil beneath our feet takes up space and provides some structural support. Pressure from the water pushes against grains of rock and clay, keeping the pore spaces open. This structural support is lost when water is removed and rock grains collapse into the empty pore spaces. The space a cube of land takes up is a combination of rock, soil, and water. When the water disappears, the land volume decreases. It accomplishes this by subsiding.
There are three climate adaptation options for coastal cities as sea levels rise. Walls and pumps are usually the first choices. Build seawalls to keep out the oceans and then install pumps to remove rainwater that can no longer drain into the ocean. Jakarta is actively pushing this option since 40 percent of the city is already below sea level.
Option number two is to rise above the fray with buildings on stilts or floating homes and offices. This solution is challenging for Jakarta, with 33 million people to elevate. And then there is option three for those with enough money, cut and run. The government has weighed the options and evidently decided in favor of option number three.
We cannot escape the reality of migration as one of the most likely tools for future climate adaptation.
Indonesia names new capital Nusantara, replacing sinking Jakarta (by Rebecca Ratcliffe; The Guardian)
Understanding Sea Level (Source: NASA)
A watery onslaught from sea, sky and land in the world’s fastest-sinking city (By Johan Augustin; Mongabay)
Melting Glaciers and Less Fresh Water (by WM House; ArcheanWeb)