Coastal flooding risk ‘three times higher if emissions don’t fall’

Workers build a water barrier with sandbags as floodwater threatens their factory at Amata Nakorn industrial estate in Chonburi province eastern Thailand in 2013

The number of people threatened by climate change-triggered flooding is about three times higher than previously thought, a new study says.

The authors urged governments to urgently conduct surveys to find out how feasible it might be to hold back the rising waters as well as take action to reverse carbon emissions, which hit a record high previous year. This is the standard method for estimating the rise in sea levels.

It says 36 million people along the Indian coastlines now live on land that will fall below the annual flood level by 2050, exposing them to risks of flooding, damage to infrastructure, loss of livelihood, or permanent displacement. Indonesia, meanwhile, is building a new capital city, as Jakarta is already feeling the threat of rising seas and is steadily sinking. What this means is that many areas and populations that were previously thought to be relatively safe from the impacts of coastal floods and rise in sea levels are in fact at risk. South Vietnam is projected to nearly disappear, affecting more than 20 million people.

The study by the US-based Climate Central organisation, published on Tuesday by the journal Nature Communications, said major coastal cities such as India's Mumbai, China's Shanghai, and Thailand's Bangkok could be submerged over the next 30 years.

Cautioning the coastal communities worldwide, the study's researchers said people must prepare themselves for much more hard times in the future than what is anticipated if current trends of greenhouse gas emissions continue.

Kulp and Strauss used more modern, higher-resolution information from airborne lidar (laser) instruments to train a computer to make corrections to the shuttle's digital elevation model (DEM).

Additionally, high tides may permanently rise above land home to 150 million people.

"As the tideline rises higher than the ground people call home, nations will increasingly confront questions about whether, how much, and how long coastal defences can protect them", said Kulp. It increases the likelihood of coastal flooding, which can damage infrastructure, destroy crops and threaten entire cities.

"This study represents very significant progress in the understanding of the risk which climate change-related sea level will cause for hundreds of million of people before the end of this century", said Jean-Pascal van Ypersele of the Universite catholique de Louvain in Belgium. This is based on the assumption that emissions cuts will be in line with the promises made under the Paris agreement.

Globally, the authors say that without rapid cuts in emissions, the sea would entirely submerge land that is not now considered at risk of flooding.

He added: "Our data improves the picture, but there is still a great need for governments and aerospace companies to produce and release more accurate elevation data. Lives and livelihoods depend on it". "We know that it's coming". The peer-reviewed study states that 237 million people in these countries occupy areas that are highly likely to experience coastal flooding once or multiple times per year by 2050. "But we have no respect for science and people who are warning us", he said, adding that we need to ensure preserving whatever natural habitats remain.