Young IRDR Scientist Leads Groundbreaking Study on Ocean Change
A new study led by Dr. Zhetao Tan, a 6th batch member of the Integrated Research on Disaster Risk (IRDR) Young Scientists Programme, has revealed that the Earth's oceans are undergoing rapid, simultaneous, and deep-reaching transformations due to climate change. Published in Nature Climate Change, the research provides a stark assessment of how marine environments are being pushed into an unprecedented state.
The international study developed an innovative framework to combine multiple ocean variables—temperature, salinity, oxygen, and acidity—to pinpoint areas experiencing "compound state change." The findings show that these simultaneous shifts, which exert extreme stress on marine life, are affecting much of the global ocean's upper 1,000 meters.
"Between 30% and 40% of the ocean's upper layers have already undergone significant shifts in at least two critical properties compared to 60 years ago," explained Dr. Tan, the paper's lead author. "In some areas, up to a quarter of the ocean shows simultaneous changes in temperature, salinity, and oxygen—a striking and alarming trend."
This research provides a critical scientific foundation for assessing climate risks. The new framework and tools developed allow scientists to clearly identify the ocean areas most impacted by human-induced climate change, offering invaluable support for policy-making and the implementation of international agreements like the UN High Seas Treaty.
Reference:
Tan, Z., von Schuckmann, K., Speich, S., Bopp, L., Zhu, J., & Cheng, L. Observed large-scale and deep-reaching compound ocean state changes over the past 60 years. Nat. Clim. Chang. (2025). https://doi.org/10.1038/s41558-025-02484-x
Bio:
Dr. Zhetao Tan is a post-doc fellow at the Laboratoire de Météorologie Dynamique, École Normale Supérieure (LMD/ENS). His research interests include physical oceanography, operational oceanography, and ocean climate change. Particularly, he mainly focused on the study of ‘climate impact-drivers’ which connect physical ocean changes to broader climate risk and climate impacts. He holds his Ph.D from the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP/CAS) in July 2024. He became a member of the IRDR Young Scientists Programme (YSP) since 2025. He is also a member of the International Quality Controlled Ocean Database (IQuOD), and the SOOP-XBT data management team (XBT-DMT).
