Trends: socio-economic, climate change
The GDP projections for Indonesia as a whole show overall growth rates of 4.5% per year between the periods 2005 and 2030, and the population of Jakarta is expected to grow from 8.8 million to up to 25 million by 2025.
The mean annual temperature in Indonesia increased by ca. 0.3°C over the course of the 20th century and the average annual rainfall decreased by ca. 2-3% across Indonesia. The temperature is projected to increase by ca. 0.1° to 0.3°C per decade over the 21st century. The annual precipitation might decrease in Java, where Jakarta is located, but different models project different changes for different scenarios. Extreme rainfall events will increase in severity and frequency in the 21st Century. In South East Asia tropical cyclones are predicted to increase in intensity, which could lead to increased storm surge heights.
Sea level rise is currently taking place at a rate of ca. 1-3 mm (0.04-0.12 inches) per year in coastal areas of Asia, and is projected to accelerate in the future. However, the rapid rates of land subsidence play a more prominent role in relative sea level change: recent estimates suggest an average subsidence rate of 40 mm (1.6 inches) per year in Jakarta and in some places in northern Jakarta up to 20cm subsidence per year. This is likely due to the high volume of groundwater extraction from the middle and lower aquifers, with secondary contributions by building/construction loading and natural consolidation of sedimentary layers. The high population growth is likely to further intensify the already severe land use pressures that play a role in flooding.