Global sea levels are rising at an unprecedented rate, exacerbating storm surges, coastal erosion, and flooding. As one of the most direct and severe consequences of climate change, this phenomenon threatens the homes of billions of coastal residents. Understanding the drivers and patterns of sea-level change, and accurately projecting its future magnitude, remains a critical and urgent challenge for the scientific community. Dr. Kewei Lyu, a researcher at the State Key Laboratory of Marine Environmental Science (MEL) at Xiamen University, is at the forefront of this exploration. His research centers on sea-level change, integrating massive datasets from satellite observations and Argo float arrays with advanced climate model simulations. By doing so, he systematically deciphers the physical "code" behind short-term fluctuations and long-term trends, aiming to elucidate the key ocean-climate dynamical processes that govern both global and regional sea-level changes.
1. Precise Constraints on the "Thermal Expansion" Effect of Global Warming
The ocean has sequestered over 90% of the excess heat generated by global warming. As the ocean continues to warm, the resulting thermal expansion of seawater has become the largest single contributor to global mean sea-level rise. Utilizing high-precision observational records from the Argo global profiling float array, Kewei has effectively constrained climate model projections of future ocean warming and its thermosteric contribution, significantly reducing the uncertainties. Furthermore, by focusing on the Southern Ocean—a pivotal global heat sink—he has integrated ocean ventilation theory with numerical simulations to provide profound insights into the dynamical mechanisms governing heat uptake, transport, and storage within this critical region.
2. Deciphering the "Dynamical Engine" Behind Regional Sea-Level Patterns
Sea-level rise is not globally uniform; rather, it exhibits vast regional differences driven by changes in ocean circulation and the resulting redistribution of heat, salt, and mass. Kewei's research marks the first estimation of the "Time of Emergence"—the point at which sea-level change signals in various ocean basins clearly exceed the range of natural variability. He has also quantified how systematic biases in the mean state of climate models impact future projections of regional sea-level changes. Invited to collaborate with leading international experts, Dr. Lyu has worked to synthesize the uncertainties in current global climate model projections and has actively participated in international model intercomparison project to advance the dynamical understanding of model simulation uncertainties. His current National Natural Science Foundation of China (NSFC) project focuses on long-term changes in ocean salinity and their role in driving regional patterns of dynamic sea level.
3. Capturing the "Decadal Pulse" of the Ocean
While satellite altimetry has provided over three decades of global sea-level observations, the extent to which these regional trends represent long-term signals remains a subject of intense debate, largely due to the profound influence of decadal climate variability. Kewei's research has illuminated the multi-scale characteristics of decadal sea-level variability in the Pacific and identified a decadal slowdown in the rapid warming of the Southern Ocean observed earlier this century—a phenomenon closely linked to internal natural variability within the climate system. Furthermore, by leveraging satellite gravity data, he and his collaborators have established a definitive link between Antarctic ice sheet mass balance and major climate modes on decadal timescales.
Currently, Dr. Lyu serves as a member of the WCRP (World Climate Research Programme) Lighthouse Activity on "Explaining and Predicting Earth System Change" and is a member of the CLIVAR (Climate and Ocean: Variability, Predictability and Change) Pacific Region Panel. He is also the Principal Investigator (PI) of a National Key R&D Program for Young Scientists, dedicated to advancing the mechanistic understanding and predictive skill of decadal climate variability.
Building upon his extensive work on global and regional sea-level change, Kewei is now extending his research to coastal regions. By exploring the intricate linkages between coastal sea-level change and large-scale ocean circulation, his team assesses changes in the frequency and intensity of extreme sea-level events (ESLs). This research initiative is designed to provide essential scientific insights for coastal communities, enabling more accurate risk assessments and the development of robust, science-based adaptation and mitigation strategies.
For more information, please visit Dr. Lyu’s website (https://mel2.xmu.edu.cn/faculty/KeweiLyu/) or contact him at kewei.lyu@xmu.edu.cn.
Biography:
Dr. Kewei Lyu received his PhD in Physical Oceanography from Xiamen University (XMU) in December 2015, then worked as a postdoctoral researcher at the University of California Irvine (2016-2018), the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO; 2018-2021), and the University of Tasmania (2021-2022). In August 2022, he joined XMU as a Professor. His research has been focusing on sea-level change, specifically combining observational records and ocean/climate model simulations to understand its short-term variability, long-term tendency, and related large-scale ocean/climate dynamical processes.
