The water level in the South China Sea has risen by 152mm since 1900, Chinese researchers have found, and the rate has accelerated in accordance with global warming.
A study published in the April issue of the Palaeogeography, Palaeoclimatology, Palaeoecology magazine said that the sea level in the South China Sea fell slightly from 1850-1900 period, but has continuously risen by 1.31mm per year on average for a total increase of 152mm (± 7 mm) from 1900-2015.
Researchers from the South China Sea Institute of Oceanology under the Chinese Academy of Sciences (CAS) reconstructed the history of the South China Sea's sea-level shift using Porites coral, a widespread coral with a high growth rate, clear annual growth layer and sensitive response to the change of seawater environment.
The coral’s oxygen stable isotopes are an ideal proxy to indicate sea-level, they said.
The researchers analyzed the correlation between the oxygen stable isotopes of Porites coral, sea-surface salinity, and temperature, as well as the rainfall in the South China Sea; and then quantitatively reconstructed the annual sea-level record.
The study found that the sea-level rise in the South China Sea may be the result of a combination of solar activity and greenhouse gases; and human-caused global warming may have been the dominant factor behind the current rapid rise of sea level.
“Clearly the findings of this study show the global community will have to do more to slow climate change, but we already knew climate change would cause the sea level to rise, threatening the coastlines of a number of countries – including minimally Indonesia, the Philippines and Vietnam,” said Murray Hiebert, a senior associate of the Southeast Asia Program at the Center for Strategic and International Studies (CSIS) in Washington, D.C.
“This will cause havoc for agriculture, fisheries, and tourism, which will create millions of climate refugees and disrupt economic growth in the region,” Hiebert said.
Sea-level rise is caused primarily by two factors related to global warming: the added water from melting ice sheets and glaciers and the expansion of seawater as it warms, scientists say.
The 2012 US National Climate Assessment provided global sea-level rise scenarios that ranged from 0.2 to 2.0 meters by 2100.
Losing momentum
“To slow climate change, it will be necessary to sharply reduce carbon emissions,” said Murray Hiebert.
“Many countries in the region had goals to try to achieve this, but these plans have been turned upside-down in the wake of Russia's invasion of Ukraine.”
“Now with the sharp drop in oil and gas exports from Russia and the rising prices on the international market, countries around the South China Sea will depend more on cheaper coal and pump more carbon into the atmosphere,” the analyst said, warning that the years 2022 and 2023 “will mark a major blow to arresting climate change.”
“This will be period in which we will lose much of the momentum that followed the COP26 summit late last year,” he said.
Much of the focus on the South China Sea over the past decade has been on the territorial disputes between China and its Southeast Asian neighbors, as well as the geopolitical tussle between China and the United States over freedom of navigation in the contested waters.
It’s time for competing nations to cooperate to avoid a looming environment catastrophe, experts said.