Studies of coral reefs in the Paracel Islands suggest that the South China Sea started warming up in 1825, at the start of the industrial revolution, according to a study by Chinese scientists.
Re-dating the start of global warming could have political implications, according to a Chinese government climate expert who was not involved in the Paracel study.
That was the year the world’s first railway began operating in England and most ocean-going ships still used wind power.
Man-made carbon dioxide emissions could not fully explain such an early rise in the warming trend, they said in a peer-reviewed paper published in Quaternary Sciences on Friday.
The Paracel coral record “will fill in some important gaps in global high resolution marine environment records and help us better understand the history of environmental change in tropical waters”, said the researchers, led by Tao Shichen from the South China Sea Institute of Oceanology.
Coral reefs provide useful climate records because the higher the temperature the faster they grow. The Paracels have one of the largest living reefs in the Asia-Pacific region, but in recent decades the archipelago has become the focal point of territorial disputes between China and Vietnam, and the construction of infrastructure has threatened the natural environment.
The researchers studied four coral reef samples retrieved from Yongxing and Yongle, two of the largest islands in the Paracels and both controlled by China’s military. The samples were drilled from locations that have been continuously underwater and suffered minimal disturbance as a result of human activity.
With the help of uranium dating technology, the researchers found the samples contained a continuous climate record going back to 1520. To ensure the accuracy of the results, parts of the samples were also sent to a laboratory in Queensland, Australia for independent analysis.
The results showed that the temperature 500 years ago was lower than it is today. The cooling trend lasted until 1825. From that date to the present, there was “a general trend of rapid increase” with the biggest spike reaching 2.3 degrees Celsius, Tao said. […]
Dating the start of climate change could have some real-life implications, according to a Chinese government climate expert who was not involved in the Paracel study.
The current goal of the Paris Agreement is to keep the temperature increase below 2 degrees Celsius by mid-century. The goal was calculated based on the assumption that the warming started from the end of the 19th century.
“If it started earlier than thought, we may need to move the deadline earlier. This may cause some confusion and inconvenience,” said the expert, who asked not to be named due to the political sensitivity of the issue.