Will YOUR city be flooded? Sea levels could rise by 2 metres if the planet warms by 5°C, claims study

Sea levels are set to rise as the average global temperature increases
Current climate agreements are trying to keep the increase below 2°C
Models of temperatures beyond 2°C will greatly increase sea level rises
New York, Miami and Guangzhou would be among those worst hit, seeing increases of almost 2m

Published: 15:00 EST, 7 November 2016 | Updated: 05:03 EST, 8 November 2016

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A warming world is bad news for Earth’s ice sheets, but a new study suggests the outlook could be even worse for coastal cities around the world.

With average global temperatures set to slip past 2°C above pre-industrial levels, sea levels will also rise.

But if the warming continues, the rising tides could see flooding in cities like New York and Guangzhou, in the fastest rate of sea rise in human history.

Rising sea levels: Climate scientists warn if temperatures continue to rise, cities like New York and Guangzhou could see huge changes in sea level, with the fastest rate in human history

Climate scientists have set a limit of 2°C in the global average, predicting an average sea rise of 20 cm (8 inches) for more than 90 per cent of coastal regions.

Some regions, including Norway and North America will see double this.

But scientists have warned that if temperatures exceed this, then things could get much worse.

Models used to predict the potential impacts of a shift in climate around the world indicate that coastal regions will be hit hard by rising sea levels.

Cities such as New York, Miami, Guangzhou and Tokyo will lose vital ground to the encroaching waters.

Some regions, including Norway and North America will see double the predicted average rate of sea level rise over the next century

RISING SEA LEVELS AROUND THE WORLD

Researchers looked at models of warming beyond the 2°C threshold.

In one scenario, a rise of 5°C by 2100 would see the average sea level rise of almost one metre (40 inches).

According to the study, almost all of the 136 largest coastal cities would experience average sea level rises of at least 0.9 m by 2100.

But the worst affected would see upper limits close to 2 m, including megacities in Southeast and South Asia, and large cities along the Atlantic coast of North America.

The researchers add that only a small number of cities in northern Europe, including Glasgow, London, and Dublin, will experience lower average sea level rises of around 0.5 m to 0.7 m.

While nations around the world have committed to limiting an increase of no more than 2°C above pre-industrial levels, climate scientists are using predictive models to show the potential impacts of ‘business as usual’ model.

In the latest study, an international team of researchers, including the National Oceanography Centre in Liverpool looked at models of warming beyond this threshold.

Writing in a paper, published today in Proceedings of the National Academy of Science, the authors explain: ‘If warming continues above 2°C, then, by 2100, sea level will be rising faster than at any time during human civilization.’

In one scenario, a rise of 5°C by 2100 would see the average sea level rise of almost one metre (40 inches).

But 80 per cent of the coastline will see waters rise by almost double this, to 1.8 metres (70 inches).

In Guangzhou alone, rapid expansion has led to almost 6 per cent of the population building on land previously unoccupied due to the risk of flooding, says the team, with people living just half a metre above sea level.

This graph shows the predictions for sea level rise (in meters) in selected cities with warming of 2 °C, 4 °C, and 5 °C

In one scenario, a rise of 5°C by 2100 would see the average sea level rise of almost one metre (40 inches). Almost all of the 136 largest coastal cities would experience sea level rises of at least 0.9 m by 2100, but Guangzhou (pictured) and others would experience almost double

If the temperature rise stays on track for 4°C and above, it could mean a sea level rise of more than 10 mm (0.4 inches) a year on average by 2083, giving vulnerable regions little time to react after 2050.

They add that such a rapid rise would displace millions of people and cost economies billions of dollars and would threaten world heritage sites and ecosystems.

The researchers add: ‘The impacts of sea level rise in coastal regions will not be uniform, and the challenge of adapting to extremely rapid sea level rise will affect individuals, communities, countries, and the global population.

‘The next generation or two will face unprecedented challenges to protect coastal United Nations Educational, Scientific and Cultural Organization Cultural World Heritage sites such as Venice, Alexandria, and Qal’at al-Bahrain as well as vulnerable tropical coastal ecosystems.’

The rapid rises in sea level would displace millions of people and cost economies billions of dollars and would threaten world heritage sites and ecosystems. Pictured is the Miami coastline, one of those set to be affected by rising sea levels