Coastal Flooding Events Could Doom 20% of Global GDP by 2100

Waves crash against a seawall near the Scituate Lighthouse on March 2, 2018, in Scituate, Mass. A major nor’easter pounded the East Coast on Friday, packing heavy rain and strong winds as residents from the mid-Atlantic to Maine braced for coastal flooding. (AP Photo/Steven Senne)

(CN) — An uptick in recent flooding poses a great risk to the world’s assets if improvements and safeguards are not made, potentially endangering 20% of the global gross domestic product in less than a century, according to research released Thursday.

Global sea levels have fluctuated over the course of human history but have seen a much faster rate of increase over the past few decades. Sea levels tend to rise due to one of two reasons: thermal expansion or melting from land-based ice. 

Thermal expansion occurs because oceans absorb heat and emissions from the atmosphere, which has become more severe recently with 2018 being a record year for ocean heating. 

Glacial melting comes mostly from Antarctica and Greenland, as atmospheric temperatures steadily increase and seasonal balance is thrown off in these regions. Both phenomena are a result of climate change.

According to the U.S. National Oceanic and Atmospheric Administration, global sea levels are continuously rising at about one-eighth of an inch per year. When this happens, storm surges will push farther inland resulting in more frequent flooding events. 

Disruptive and expensive flooding events called nuisance flooding are estimated to have increased anywhere from 300% to 900% within U.S. coastal communities over the past 50 years.

The study, published in the journal Scientific Reports, was led by University of Melbourne doctoral candidate Ebru Kirezci. She and her colleagues created a model of different scenarios of sea level rises combined with different levels of greenhouse gas emissions to determine the extent of the threat of future flooding events. 

The model uses a combination of sea level data under stormy conditions with factored-in projected sea level increases to demonstrate what effects we can expect to see by the year 2100. 

This is because higher sea levels bring more powerful storms that move slower and unleash more rain on coastal communities, and have the potential to decimate less developed coastal communities. A 2014 study conducted by National Hurricane Center deputy director Ed Rappaport found that almost half of the total fatalities from Atlantic tropical hurricanes that occurred between 1963 to 2012 were attributed to storm surges.

It was important to use this information to estimate how much of the population and the world’s assets are in danger from coastal flooding. According to NOAA, almost 40% of the U.S. population lives in high-population density coastal areas, and eight of the world’s 10 largest cities sit near the sea. 

By comparing their model’s data with population statistics from coastal areas and their corresponding GDP, the team was able to identify the regions most vulnerable to coastal flooding and assess the potential damage.

The authors warn that if emissions are high and flood protections are lacking, a projected 48% of coastal land could be impacted by flooding by 2100. These areas include Southeastern China, Australia’s Northern Territories, Bangladesh, West Bengal and Gujurat in India, North Carolina, Virginia and Maryland and northwestern Europe. 

Furthermore, the authors warn that a staggering 287 million people — about 4.1% of the global population — could be at risk of these flooding events by 2100. The flooding events could also result in the loss of $14.2 trillion in assets. 

In many urban coastal cities, assets and infrastructure are both at risk as floods threaten roads and bridges, water supplies and power plants. This is becoming increasingly likely due to population growth and rapid economic development. 

Floodwater can also contaminate aquifers and soil, which results in expensive repair jobs. Outside of cities, ecosystems are also greatly disrupted by storm surges and floods, which can be devastating for commercial fisheries and agriculture. 

These results add to the long list of studies urging the world to reduce greenhouse gas emissions before conditions deteriorate further, particularly for the sake of the at-risk areas of northwest Europe, southeast and eastern Asia, the northeast U.S. and northern Australia. 

The authors also call for meaningful investments in flood defenses in threatened areas to avoid a catastrophic impact on the population and the economy. This is going to be increasingly important in the wake of Covid-19 as research shows that coastal communities have been hit the hardest by the pandemic and likely would struggle immensely to recover from flood damage.

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