Due to rising sea levels, great swathes of coastal cities will be under water by 2050—and entire island nations are likely to disappear. In part one, we look at the big picture on how bad it will get and why. In part two, we will look at how a country like Tuvalu deals with its own extinction.
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Researched by: Nirmal Bhansali & Anannya Parekh
First: What’s up with those rising sea levels?
When the planet heats up, sea levels rise due to two reasons. One: glaciers and ice sheets melt—adding more water to the oceans. Two: the warm water in the oceans expands—adding to their volume. Sea levels have already risen around nine inches, or roughly 23 centimetres, since 1880. This eerie ‘porthole’ animation shows you how the waters have risen for the past 30 years:
The rise is also accelerating—it was twice as fast in the most recent decade than 1993-2002.
The really scary bit: is that it’s too late to stop the oceans from rising:
Part of the problem is that even if the world stopped emitting greenhouse gases immediately — which it will not — sea levels would continue to rise. Even in the best-case scenario, it’s too late to hold back the ocean. The reason for this is not widely known, outside the science community, but is crucial. The systems causing sea level rise — specifically, the thermal expansion of the ocean and the melting of glaciers and ice sheets due to global heating — have a centuries-long time lag.
Next: Which parts of the world are in serious trouble?
There are best and worst case scenarios—based on how hot our planet will get. But here’s the main takeaway: “Most scientists now agree that even if countries took steps today to reduce greenhouse gas emissions, average sea levels would still rise by up to 6.5 feet [1.98 metres] by the end of the century.”
Before we dive in: Here’s the important bit to note: we may not be able to prevent sea levels from rising significantly, but coastal areas can take mitigating measures to save themselves.
A headline that says, for example, more than a quarter of the Netherlands will be underwater by 2100 – that sounds very dramatic. But at the moment, people in the Netherlands are walking around and riding their bikes below sea level. There are coastal defence structures in place. And if you say 200 million people are going to be affected by rising sea level: well, anyone who lives on the coast is affected in some way, but it doesn’t actually mean that they’re going to lose their house right away.
OTOH, many small island nations may not be able to avoid their fate. And there are limits to how much we can do:
[Climate change expert Benjamin] Strauss offered the example of New Orleans, a city below sea level that was devastated in 2005 when its extensive levees and other protections failed during Hurricane Katrina. “How deep a bowl do we want to live in”? he asked.
On to the bad news: In October, 2019, Climate Central published alarming data which revealed that many cities will become uninhabitable by 2050. The reason: coastal flooding, where the sea water suddenly enters and swamps large swathes of land. So these areas may not be entirely under water, but it will be impossible to live there. The big picture predictions were as follows:
- 150 million people are now living on land that will be below the high-tide line by 2050. By 2100, land that is home to 200 million people could sink permanently below the high tide line—making it unlivable.
- The reason: sea levels are expected to rise between 2 to 7 feet (0.6 metres to 2.1 metres) over the next three decades.
- 70% of the people at risk are in eight Asian countries: China, Bangladesh, India, Vietnam, Indonesia, Thailand, the Philippines, and Japan.
- The cities expected to disappear or be mostly underwater include: Ho Chi Minh City, Bangkok, Alexandria, Basra, Shanghai and Hong Kong.
Most catastrophically this: Islands in the Pacific Ocean are even more vulnerable. While the global average rise in sea level is 3.2 millimetres, parts of the western Pacific are seeing an average jump of 8-12 millimetres per year—due to wind patterns that are moving more water to the region. It is likely that five nations—the Maldives, Tuvalu, the Marshall Islands, Nauru and Kiribati—will become uninhabitable by 2100—creating 600,000 stateless climate refugees.
But what about India?
As we said, there are best and worst case scenarios. For example, the image below depicts what Mumbai would look like at 1.5°C and at 3°C—which is where we are headed if we do nothing:
But it is more likely that we will do our best to at least keep the warming to 2°C. That’s the premise of a 2022 study that looked at six coastal cities—and found we’ll definitely lose some of their most iconic areas. For example: in Mumbai, the Haji Ali dargah, Western Express Highway, Bandra-Worli Sea-link, and Queen’s Necklace on Marine Drive will disappear.
Far more telling: is the Coastal Risk Screening Tool that predicts the effects of global warming by temperature and year. Below is Mumbai in 2100 with a 2°C rise in temperature:
And this is Kerala:
And this is Kolkata—which looks the worst:
The bottomline: These cities can at least hope to save themselves by taking emergency measures—like fortifying sea walls. But what about the nations that will be totally wiped out? We look at how a country deals with its own extinction in part two.
New York Times offers a good overview of rising sea levels and climate change. The Guardian looks at best and worst case scenarios. LiveScience and New York Times look at which parts of the world will be most affected. We did a Big Story on Climate Central’s 2019 study—and how it will affect major cities, including India. Or you can read the research paper in Nature. You can check out the Sinking Cities Project, which provides a deep dive into how six different cities are responding to rising sea levels and incursion.