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  1. Environment
30 October 2023

How quickly are sea levels rising?

Swathes of Norfolk will be underwater in the coming decades, reveals an interactive data project by the New Statesman.

By Nick Ferris and Giacomo Boscaini-Gilroy

The US state of Louisiana is losing a football field of land every hour. The present coastal areas of Pacific island nations such as Kiribati and the Marshall Islands are expected to become largely uninhabitable by the middle of the century. And even the Netherlands, renowned for its huge network of dikes, may lose huge parts of its landmass.

These are the findings of a variety of climate scientists in a world where sea levels are rising by 3.4mm a year. And if carbon emissions continue to rise, even worst-case scenarios could become a whole lot worse for the 40 per cent of the world’s population that lives in coastal areas.

A new data project from the New Statesman models different sea level rises against a digital elevation model of coastal areas from the non-profit research organisation Climate Central. Our map shows how even in a scenario where the world meets the core ambition of the 2015 Paris Agreement – that emissions reach net zero by the middle of the century, and warming is kept below 2°C – sea levels are expected to rise by 0.4m by 2100.

By contrast, if energy-related emissions keep rising unmitigated (emissions grew 0.9 per cent year-on-year in 2022), sea levels are likely to rise by 0.8m by 2100, according to the Intergovernmental Panel on Climate Change (IPCC).

To demonstrate just how devastating the global sea level rise could one day become, we also show the 7.4m sea level rise that would occur if the entire ice cap of Greenland were to melt. Such a scenario is not totally out of the realm of possibility: recently published analysis of a Greenland ice core has suggested large parts of the island were ice-free around 400,000 years ago, when global temperatures were similar to what the world currently experiences.

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[See also: Is nuclear power the key to reaching net zero?]

The map also shows the 70m sea level rise that would occur if all Earth’s ice caps and glaciers melted, according to the US Geological Survey. Such a scenario is not expected in any climate models, but it is not without precedent: Earth was last ice-free 34 million years ago.

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Interactive graphics by Giacomo Boscaini-Gilroy

If global warming is kept below 2°C, our map shows that in Europe large areas of the continent will nevertheless be below sea level by the end of the century. The situation is starkest in the Netherlands, where dikes, storm barriers, pumps and other adaptations protect the 26 per cent of the landmass that lies below sea level. And even the Netherlands would struggle to adapt should the world fail to curb growing emissions. According to the Dutch government, current flood defences will only be adequate up to 2050. Improving them will be slow work: the past 30 years of flood defence development has allowed the country to deal with just 40cm more of sea level rise.

In the UK, too, parts of Norfolk are expected to lie under water in the coming decades unless drastic global action is taken to reduce emissions.

The map shows how small island nations are among the most vulnerable to climate change. Even in a scenario where warming is limited to below 2°C, we find catastrophic sea level rises in their coastal areas.

“The map demonstrates the findings of the IPCC: That if unabated emissions continue and global warming increases, the Pacific region faces a 0.8m sea level rise by 2100,” said Pa’olelei Luteru, ambassador of Samoa to the UN, and current chair of the Alliance of Small Island States (AOSIS) at the UN. “This will mean even more severe flooding, even worse loss of livelihoods and lives. This is not a climate threat, this is a very real crisis we are struggling with right now. 

“My home of Samoa, and throughout other Pacific islands, our communities are already beyond their adaptation limits, dealing with coastal erosion, drinking water salinity, and vegetation destruction.”

Satyendra Prasad, a former Fijian ambassador to the UN, added: “There is a sense of hopelessness across so many islands now. Long before communities move to territories on higher land, they will face heightened water and food insecurity, and more fierce and frequent super cyclones will mean that states begin to fall off the fiscal cliffs on which so many now sit.

“And at even a 2°C temperature rise, many islands will have been lost and displacement of whole populations in countries like Kiribati and Tuvalu will occur on a substantial scale.”

The impact of rising sea levels is also striking in the southern United States. Louisiana lost an estimated 1,883 square miles of land between 1932-2010 to the sea. “Sea level rise is just one way that Louisiana is impacted by climate change – we are also seeing more hurricanes, more extreme heat and more flooding from rain events,” said Charlotte Clarke of Common Ground Relief, an environmental charity based in southeast Louisiana.

“There are many major cities that are at risk, many millions of people are imperilled, and huge threats to the economy,” added James Karst, from the Coalition to Restore Coastal Louisiana. “In Louisiana, we risk the collapse of our fisheries, some of the most bountiful in the world. We risk our culture, and the communities – such as the indigenous people in the Isle de Jean Charles – that dot our coastline. And we risk our industries and ports, which are among the busiest in the world.”

[See also: Carbon emissions tracker: How do countries compare?]

This article was originally published on 8 August 2023.