OCES Departmental Seminar: Local to Global Drivers of Past and Future Sea-Level and Coastal Environmental Change
Geological proxies provide valuable archives of the sea-level response to past climate variability over periods of more extreme global mean surface temperatures than the brief instrumental period. The geological record provides information to assess the relationship between sea level and climate change to develop a firmer basis for projecting the future. Characterizing past sea-level changes and projecting future sea-level rise shares two key challenges: (1) regional and local sea-level changes vary substantially from the global mean, requiring understanding of regional variability to interpret records of past changes and generate local projections, and (2) uncertainty persists in both records of past changes and in the physical and statistical modeling approaches used to project future changes, requiring careful quantification and statistical analysis.
Here, the mechanisms that drive spatial variability and methodologies and data sources for piecing together lines of evidence related to past sea-level variability are reviewed. Recent efforts to develop standardized global databases of past sea-level change to estimate the magnitudes and rates of global mean sea-level change and identify trends in spatial variability and its driving mechanisms are also summarized. In particular, the most recent interglacial period, the Holocene, is the focus of this talk. I highlight several recent applications of sea-level databases to define thresholds of coastal wetland ecosystems to rapid rates of sea-level rise, provide high-quality constraints to tune geophysical models of the glacial-isostatic adjustment process, address open questions regarding the nature of Holocene sea levels, and improve local projections of future local sea-level rise.
Dr. Nicole Khan is an Assistant Professor in the Department of Earth Sciences at the University of Hong Kong. She received her B.A. in Earth Science and Mathematics from Boston University and Ph.D. from the University of Pennsylvania, where she studied past changes in sea level. Her research concerns deciphering the internal and external drivers of past sea-level change to better understand how these mechanisms will affect future changes. She is project leader of the HOLSEA (Geographic variability of HOLocene SEA level), on the steering committee of PALSEA (PALeo-constraints on SEA-level rise), and Vice President of the Coastal and Marine Processes Commission of the International Quaternary Association. She is also a contributing author to the IPCC AR6 report.