Jakarta and Semarang are predicted to be engulfed by seawater by 2050, based on evidence by the Copernicus Sentinel-6 satellite. The current sinking rate is reaching almost 20 cm annually in both coastal cities, as reported at the World Economic Conference in May 2022, due to climate change, rising sea levels and excess groundwater extraction leading to land subsidence. Therefore, the objective of this study is to analyze the sinking of both coastal cities of Jakarta and Semarang, using indicators of vulnerability, exposure, and impact by 2050.

The YEW Disaster Severity Index (DSI) was used to analyze the impact, vulnerability, and exposure attributed to sinking. Data were obtained from real-time Google, Copernicus Sentinel-6 satellite, and triangulated with United Nations Office for Disaster Risk Reduction, World bank Data, Government of Indonesia Central Bureau of Statistics, as well as reputable journals.

The impact analysis on the sinking of Jakarta and Semarang, calculated in April 2022, using the YEW DSI, scored a High DSI impact of 6.03 and a Moderate DSI impact of 5.76, for each town respectively. Jakarta and Semarang also scored more than 100% baseline ability to cope on the YEW DSI indicators, which accounted for five vulnerability indicators and one exposure indicator of a total 13 million population affected. By 2050, both cities will be 5.6 meters below sea-level, with a constant current sinking of 20 cm per year.

At present, vulnerability and exposure of the affected population account for a total of 13 million in both coastal cities. The analysis showed the inability to cope within local capacity, indicating a response is needed. The future of Jakarta and Semarang is in the hands of local, national, and global decisions and policymakers, in mitigating its impact through forest land conservation, adaptation, and relocation of the affected population.