Jakarta is set to become the biggest city in the world with a population of 35.6 million by 2030. If forecasts are correct, the Indonesian capital will dethrone Tokyo as the city with the most people and become the first emerging economy to be the number one megacity.

The findings came out of a report by Euromonitor International reviewing the rate of growth of developing cities.  The reason why once booming developed places like Tokyo, Moscow, London, New York, and Paris are being overtaken by emerging cities is in part thanks to low birth rates. New York came out top for wage per hour and productivity but is wildly outnumbered in terms of people and populace. By 2030 six new cities are expected to join the megacity scene, with Chicago being the only one from a developed country. Baghdad and Bogotá are also set to join the ranks over the next 12 years.

But as Jakarta’s population numbers mushroom, the city faces a variety of serious issues. With the current population standing at 30 million, and few alternative transport routes, the city’s roads are experiencing massive amounts of gridlock. According to TomTom’s congestion index, it was the third worst city for traffic in 2018, with residents spending an additional 184 hours per year stuck on the roads. The city’s first subway system is set to open next year; costing $1.5 billion and spanning 15.7 kilometers (9.76 miles), the new transport system has been 24 years in the making.

The other major issue in the city is that it’s sinking faster than any other city in the world, coupled with rising sea levels forecasts say the entirety of northern Jakarta could be underwater by 2050. Last month a $40-billion attempt to create a Dubai-style series of artificial islands off the coast of the capital was stopped in its tracks as officials canceled work permits because developers hadn’t fulfilled all their environmental obligations. Although the project has been pushed by the Indonesian government, it’s faced several stumbling blocks.