Sea levels are rising faster than at any time in the last 4,000 years. Here’s why

Published on 20/10/2025 - 12:25 GMT+2

Sea levels are rising faster than astatine immoderate constituent successful nan past 4,000 years, highlighting nan urgent request for “global and local” action.

New investigation has warned that ambiance alteration and quality activities are driving nan surge, which poses a superior threat of flooding for awesome cities astir nan world.

The study says that while rising seas are a world issue, China faces a “double threat” arsenic its largest and astir economically important cities are peculiarly prone to sinking.

How quickly are oversea levels rising?

Scientists astatine Rutgers University examined thousands of geological records from respective sources, including ancient coral reefs and mangroves, which are often utilized arsenic a “natural archive” of pastsea levels.

They reconstructed oversea level changes going backmost almost 12,000 years to nan opening of nan Holocene, nan existent geological epoch which began astir 11,700 years agone aft nan past awesome crystal property ended.

Published successful Nature, nan findings show that since 1900, global oversea levels person accrued astatine an mean complaint of 1.5 millimetres a year.

According to Yucheng Lin, who conducted nan research, this gait exceeds immoderate century-long play successful nan past for millennia.

Why are oversea levels rising?

The study outlines 2 “major forces” that are driving nan acceleration of oversea level rise: thermal description and melting glaciers.

As ambiance alteration increases nan somesthesia of nan planet, oceans are absorbing much power and expanding. At nan aforesaid time, crystal sheets successful polar regions are pouring astatine unprecedented rates, adding much h2o to nan oceans.

“Getting warmer makes your water return up much measurement and nan glaciers respond faster because they’re smaller than nan crystal sheets, which are often nan size of continents,” says Lin.

“We are seeing much and much acceleration successful Greenland now.”

The Greenland Ice Sheet mislaid 80 cardinal tonnes of crystal complete nan 12 months from September 2023 to August 2024, marking nan 28th twelvemonth successful a statement that it has mislaid much crystal than it produces.

Currently 1 of nan world’s biggest freshwater resources, nan Greenland Ice Sheet contains h2o that would origin nan balanced of 7.4 metres of world oversea rise.

For each centimetre of oversea level rise, astir six cardinal group connected nan satellite are exposed to coastal flooding.

A ‘coastal crisis’

Researchers pass that deltas - flat, fertile regions that are adjacent to nan h2o - will beryllium deed nan hardest byrising oversea levels.

These areas are often utilized for farming, proscription and municipality development, meaning their demise could trigger vulnerabilities successful nan world proviso chain.

“Centimetres of oversea level emergence will greatly summation nan consequence of flooding successful deltas,” Lin adds.

“These areas are not only important domestically, they’re besides world manufacturing hubs.”

Although nan study focused connected China, Lin argues nan aforesaid lessons tin beryllium applied to awesome cities, including New York, Jakarta and Manila, which are built connected low-lying coastal plains and look akin risks.