Hong Kong(CNN) Sea levels on China’s coastline have hit their highest on record for the second year in a row, rising more quickly than the global average and posing a serious threat to coastal cities such as the financial hub of Shanghai.
In 2022, China’s coastal sea levels were 94 millimeters (3.7 inch) higher than “normal,” defined as the average over the 1993-2011 period, making it the highest since records began in 1980, an official at the Ministry of Natural Resources said Wednesday at a news conference.
The swell was 10 mm higher than in 2021, when the previous record was reached.
The temperature of China’s coastal waters has increased significantly due to global warming, and the rise in sea levels has accelerated, said Wang Hua, head of the marine forecasting and monitoring department at the ministry.
China’s sea levels have increased by an average of 3.5 mm per year since 1980, and an average of 4.0 mm per year since 1993 — higher than the global rate over the same periods, Wang said.
The global mean sea level has risen 3.4 mm a year over the past three decades, according to NASA.
“In the last 11 years, from 2012 to 2022, China’s coastal sea levels were the highest since observations were first recorded,” Wang said at the news conference, which released the latest annual report on China’s sea levels.
About 45% of China’s population of around 1.4 billion and more than half of the country’s economic output comes from coastal regions.
The Chinese coast is home to important metropolises including Shanghai, the country’s most developed and richest city, as well as the port city of Tianjin and the tech hub of Shenzhen.
Over the past four decades, rising sea levels along the Chinese coast have caused long-term effects, including the erosion of coastal ecosystems and the loss of tidal flats. They have also affected groundwater supply and increased the damage caused by storms, floods and salt tide intrusion, Wang said.
While the sea swelled, land in coastal regions had sunk, exacerbating the problem, he added.
In 2022, high sea levels along the Chinese coast aggravated the impact of storms, dealing a severe blow to the provinces of Guangdong, Zhejiang and Shandong. The rises also contributed to heavy coastal flooding in Zhejiang and Hainan province, causing great economic loss, according to Wang.
Correction: a previous version of this story mischaracterized the global increase in sea levels. It is an average of 3.4mm a year