Jakarta is frequently subjected to earthquakes, landslides and flash floods that take lives and displace thousands of people. Uncontrolled groundwater drainage has led the city to sink at alarming rates, which, combined with rising sea levels is expected to fully sink the city by the end of the century. 

Earth.Org has mapped the extreme flooding potential Jakarta could face by 2100. 

Jakarta is the largest city and capital of Indonesia. It lies on the northwest coast of Java at the mouth of the Ciliwung river. With a population of 10 million people, and a metropolitan area housing 30 million, it is set to become the world’s largest mega-city. The 662 km2 area it covers averages 7 metres above sea level, but 40% stands below this threshold, especially in the northern, sea-adjacent area. When high tides coincide with heavy rain, water fills out these low-lying areas causing casualties (66 in 2020), infrastructure damage and crippling socio-economic activity.

Jakarta has been steadily growing in population and size since the 1940s and many of its inhabitants come in search of better economic conditions. This expansion has been poorly controlled by the government, and has led to a particularly harmful practice. Poorer households use groundwater because piped water is considered a luxury. Excessive groundwater drainage is making Jakarta sink about 5 to 10 centimetres each year, about 130 times faster than sea level rise. 

The dangerous combination of rising waters and sinking land means Jakarta will likely be partly submerged by 2050. The government plans to spend USD $33 billion to move the entire city, but they maybe could have cushioned the blow had they regulated the city’s expansion with more care. 

We have modelled what extreme flooding, combining storm surges, high tides and rising sea levels would look like in Jakarta by 2100 if no action is taken.

sea level rise 2100 jakarta

Sea level rise projections by 2100 for two scenarios with the amount of rise in meters indicated (mild = 3m; extreme = 5m). Percentage and total population displacement indicated bottom right.

Methodology

Global mean sea level is projected to rise by 2m at the end of this century. However, in order to determine local sea level rise (SLR), one has to take into account local coastal flood levels which could be 2.8m above Mean Higher-High Water (MHHW) at extreme forecasts. These local levels bring variability to the projected SLR from 1m to 6.5m (eg. Rio vs Kolkata).

The SLR scenarios used in this study are based on the forecasts from Climate Central – Coastal Risk Screening Tool  with the following parameters:

Sea level Projection Source: is from two highly cited journals by Kopp et al., estimating SLR mainly due to ocean thermal expansion and ice melt. The mid-range scenario projected 0.5-1.2m of SLR based on different representative concentration pathways (RCP) defined by the IPCC. While the pessimistic scenario added more mechanisms of ice-sheet melting, estimating SLR at 1m-2.5m in 2100, with projection of 10m SLR at 2300.

Coastal Flooding: More frequent coastal flooding is a direct impact of sea-level rise. Based on the Global tides and surge reanalysis by Muis et al., (2016), it is estimated that the extreme coastal water level could be from 0.2 – 2.8m over mean level. While in extreme cases like China and the Netherlands it could experience 5-10m of extreme sea levels. Here, the coastal local flood level is added on top of the projected SLR.

Pollution Scenario: allows to choose the RCP, the greenhouse gas concentration trajectory defined by the IPCC.  The mild level is based on RCP4.5, of 2°C temperature rise; while Extreme level is based on RCP 8.5, of 4°C temperature rise.

Luck: applies to the the baseline SLR, defined in the “Sea level projection” section, upon which we add flooding. “Mild” refers to the mid-range scenario of 0.5-1.2m, and “extreme” to the pessimistic scenario of 1-2.5m. We used the high-end value of each scenario (mild = 1m; extreme = 2.5m).

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