The dividends accruing to Nigeria from its 853-kilometer coastline may be reversed as a new report warns that rising seas could affect three times more people and submerge some of the world’s coastal cities by 2050.

Research by Climate Central, a science organisation based in New Jersey, and published in the journal, Nature Communications, shows that 300 million people currently live in areas that become flooded at least once a year, and that half of these places would be below the high tide line by mid-century.

The scientists developed a more accurate way of calculating land elevation based on satellite readings, a standard way of estimating the effects of sea-level rise over large areas, and found that the previous statistics were far too optimistic.

At-risk areas include large portions of heavily populated cities like Mumbai, which is home to more than 18 million people and could be almost entirely underwater in the next 30 years. Models show that the worst effects could be seen across Asia where countries like India saw a sevenfold increase in the number of people set to be affected by annual floods, and China had a threefold increase.

According to the scientists, if cities must invest vastly greater sums in protective measures like seawalls and other barriers; they must do it quickly.

Efforts to get reactions from the Lagos State government were unsuccessful. A text message sent on Monday to Commissioner for Environment and Water Resources Tunji Bello was neither acknowledged nor replied to as at press time.

The research is coming on the heels of a landmark United Nations report that laid bare the severe risk to coastal cities and low-lying islands from climate change and the parlous state of the world’s oceans.

The report from the Intergovernmental Panel on Climate Change, a gold standard of scientific research, outlined the threat to hundreds of millions of people from the acceleration in the rate at which sea levels are rising, caused by a combination of melting ice in polar regions such as Greenland and Antarctica and the expansion of the oceans as the water warms.

The researchers warned that extreme floods, the likes of which have historically only occurred once per century, were likely to happen at least once per year by 2050 in many regions, especially the tropics, even if global warming is limited to 1.5C.

Globally, sea levels rose in the last century and various projections suggest substantial increases this century due to climate change. In Nigeria, there is no up-to-date sea level rise (SLR) assessments for the coast. Much of the Nigerian coast is low-lying with the consequence that a one to three meter rise in sea level, which may result from eustatic or climate change, will have a catastrophic effect on human activities in this region.

A study by the University of Plymouth found that a sea-level rise of three to nine feet would be disastrous. It examined the consequences of continued sea-level rise with a focus on erosion and inundation for the Nigerian coast and mulled the idea of coastal partnerships (CPs).

(The Guardian)