China will step up monitoring of the impact of climate change on marine ecosystems as the global climate crisis worsens, a Ministry of Ecology and Environment official said on Aug 26.

"Global climate change has resulted in a continuous rise in seawater temperature," said Zhang Zhifeng, deputy head of the ministry's Department of Marine Ecology and Environment. "China has also experienced a marked increase in sea surface temperature in recent years."

The sea level rise triggered by temperature changes will intensify saltwater intrusion, soil salinization and storm surges. These disasters will cause damage to key marine ecosystems, such as mangrove forests, and result in degradation of coastal wetland and key habitats, Zhang added.

From 1980 to 2020, the country on average witnessed a sea level rise of 3.4 millimeters a year, which is higher than the global level, according to the Blue Book on Climate Change in China 2021, which was published by the China Meteorological Administration this month.

According to the latest landmark report of the United Nations Intergovernmental Panel on Climate Change, coastal areas will see continued sea level rises throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion.

Extreme weather events that previously occurred once in 100 years could happen every year by the end of this century, said the report.

Zhang said temperature change will also increasingly result in a series of other environmental hazards, including red tides caused by algal blooms.

Oceans have the largest capacity to absorb carbon dioxide in the world, but Zhang warned that having more of the gas in seawater will cause "ocean acidification", which reduces seawater pH values.

The world has generally experienced a 0.1 decrease in the pH value of surface seawater from the pre-Industrial Revolution era. "It looks like a very small number, but it is a very big change in pH value. The ocean acidification trend will sustain," he said.

Ocean acidification has occurred in bottom seawater in some areas of the Bohai and Huanghai seas, water monitoring has found.

The chemical reactions may affect the growth of shellfish and coral and have a negative impact on the function of the entire marine ecosystem, Zhang said.

The ministry will include the impact of the rise of seawater temperatures and acidification in its regular marine monitoring. It will also promote a pilot program to monitor their effects on shellfish and coral, he said.