- October 23, 2025
- Rutgers University
- Sea levels are rising faster than at any time in 4,000 years, scientists report, with China’s major coastal cities at particular risk. The rapid increase is driven by warming oceans and melting ice, while human activities like groundwater pumping make it worse. In some areas, the land itself is sinking faster than the ocean is rising. Still, researchers see progress as cities like Shanghai adopt new technologies to stabilize the ground and prepare for the future.
Friday, October 24, 2025
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TRANSCRIPT:
Did you know that China's coastal cities are sinking and the sea levels are rising at record speeds? Well, a team of scientists led by Rutgers University has uncovered the truth. Sea levels today are climbing faster than at any time in the past 4,000 years. Their big finding, well, China's coastal cities are at some of the highest risk in the world. And this is not just a headline scale, but it is backed by thousands of geological records.
The researchers dug deep. They analyzed ancient coral reefs. They studied mangro formations. These natural time capsules hold evidence of how high the seas once reached. With that data, scientists reconstructed ocean changes going back almost 12 thousand years. So, how fast are the waters rising?
Well, according to the study published in the journal Nature,
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global sea levels have gone up by around 1.5 ml each year since 1900. Now that may sound small but it is the fastest average rise in any century long period over the last four millennia. It is a big leap for a system that's usually slow to change.
Now the lead researcher Yuchang Lin explains what is exactly behind this speed. Well, two major forces are at play. Thermal expansion and melting ice. When the planet heats up, the oceans absorb that heat and water expands.
But that's not all.
Melting glaciers and ice sheets, especially in Greenland and Antarctica, dump huge amounts of water into the oceans.
More heat, more water, more risk for everyone on the coast.
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So for China, the threat is doubled. Many of its biggest cities, for example, Shanghai, Shenzhen, and Hong Kong sit on soft sinking sediment. Deltas made of waterlogged land are naturally unstable. But human activity is making it even more worse. Extracting ground water for daily uses speeds up the sinking process. Subsidence, the slow sinking of the earth happens from both natural and man-made causes.
Now in Shanghai, some areas dropped more than 1 m in the last century. That's far faster than the pace of global sea level rise. And every cm higher the ocean goes, the risk of flooding spikes for these vital urban and industrial areas.
Why does it matter outside China? Well, these delta regions aren't just local. They're also a crucial part of the global supply chain. So, whenever the manufacturing hubs face flooding, international commerce also feels the shock.
So, these regions are flat and fertile, perfect for development, but highly exposed to any change in water levels. So, what is being done about this big problem?
Well, the news is not all grim. Cities like Shanghai have slowed the subsidence by controlling groundwater extraction. They are reingjecting fresh water and stepping up regulations. Scientists have mapped the most vulnerable zones, giving city planners the tools they need to protect people and businesses.
So this study reaches far beyond China. Other major cities like New York, Jakarta, Manila all are built on similar low-lying land. They face the same threats. Experts remind us that while deltas are great for farming, fishing, and building cities, they're also especially prone to sinking when human demand outpaces nature's balance.
One more thing is that the Rutgers team used a smart technology, too. Their software helps model environmental changes across millennia that's vital for seeing the bigger picture. The study got support from the National Science Foundation and NASA, giving it global credibility.
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So the bottom line is this. Science tells us that China's coastal cities and many others worldwide must adapt fast. Sea level rise is no longer a distant future threat. It's happening now. And for many, it's a matter of survival.
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