Providing jobs and services for the 1.1 billion people expected to move to Asia's cities over the next 20 years is a task of a magnitude "never before attempted by humanity," Asian Development Board (ADB) President Haruhiko Kuroda warned on Wednesday, according to dpa. Asian cities are growing by more than 100,000 people a day, he told the World Cities Summit in Singapore. The cities need increased investment in sustainable infrastructure, "which will only come through more appropriate and relevant financing options," Kuroda said. A 3-billion-dollar shortfall in urban infrastructure investment is recorded every year, he said, resulting in greater deterioration. In another grim statistic, Kuroda said more than half a billion people live in slums. Referring to a new ADB report on Managing Asian Cities, Kuroda said London took 130 years to grow from 1 million to 8 million while Asian cities are fast attaining a "tidal wave of humanity." The report calls for a "wholesale rethink" about how laying out cities in an energy-efficient way. Cities like Singapore and Busan, South Korea, show it is possible "to grow at breakneck speed without undermining nature," said Dr Ahmed Djoghlaf, executive secretary of the UN's Convention on Biological Diversity. Speaking at a discussion, he attributed the two cities' progress to a partnership between government and green groups on the same wavelength. Philadelphia, Dublin, Bilbao and Barcelona were also praised for their model urban planning. Singapore was also cited for its public transport system. "Cities have to be returned to the people," said Sanjeev Kumar Lohia of India's Urban Development Ministry, which has implemented some of the city-state's best practices in bus and rail systems.