The global populace, most specially those living along the world's coastal cities, either pack up and relocate to high grounds as early as now or accept their fate as the intensity of floods currently lapping the Earth will get more severe and damaging in the coming years.

Stéphane Hallegatte, an economist at the World Bank, warned that global change, inflicted by careless treatment and consideration to the world's resources, will all the more provoke severe flooding that could render useless any mitigation plans and efforts.

According to a paper published in Nature Climate Change, severe flooding on the 136 largest coastal cities will put global damages to as much as US$1 trillion per year, with those in the developing countries hardest hit.

"No city is doomed, but we have to expect huge disasters in the future. And better international coordination to provide support for the affected countries is really important," Mr Hallegatte, senior economist of the WB's Sustainable Development Network and lead author of the study, said.

"For each city we assessed the total cost of potential damages," Mr Hallegatte added. "But we also looked at the relative losses, comparing the absolute cost to the city's gross domestic product, to give an idea of the actual vulnerability of each city."

And even if the global coastal cities do improve and intensify mitigation efforts, there remained a nine-fold increase in losses to $52 billion per year by 2050.

The cities with the highest projected annual losses by 2050, based on the study, were Guangzhou ($13.2 billion), Mumbai ($6.4 billion) and Kolkota ($3.4 billion) in India, Guayaquil ($3.2 billion) in Ecuador and Shenzhen ($3.1 billion) in China.

Also included were Miami ($2.5 billion), Tianjin in China ($2.3 billion), New York ($2 billion), Ho Chi Minh City in Vietnam ($1.9 billion) and New Orleans ($1.9 billion).

"More disasters are expected in the future, and it is very likely that the poor will be disproportionally affected," Robert Nicholls from the University of Southampton, United Kingdom, and another author of the study, said.

"We cannot observe the risk increasing in real life until a disaster actually occurs, which is why it's important to analyse and reduce the risk in advance," Mr Hallegatte said.