The coastal zone, crucial for sustainable development in the land - sea interaction area, has rich resources and diverse ecosystems that provide great value to human society. It is a typical complex system composed of interconnected and mutually interacting physical-biological-social subsystems with multiple elements. The coastal zone experiences high-intensity human activities with highest densities in population, GDP and large urban agglomerations and exhibits characteristics such as multi-scale spatio-temporal variations and highly dynamic changes. It forms thus a regional earth system under strongest human influence.
Since the Industrial Revolution, human activities (the social subsystem) have predominantly altered the physical structure of the coastal zone (e.g. the coastline) and the pattern of land-sea interaction. This, in turn, has affected the transport, transformation, and fate of land-sea substances, especially biogenic elements such as carbon, nitrogen, and phosphorus, causing drastic fluctuations in the state and pattern of the coastal zone ecosystem (the biological subsystem). Climate change has further magnified the above effects. Consequently, the coastal zone system may have entered a period of abrupt change, is approaching or has already crossed the tipping point, posing major challenges to the coordinated development of land and sea and seriously threatening the sustainable development of the social economy. This situation is of great urgency.
Understanding the science of the complex coastal zone is critically important. A core part is to study and simulate its tipping processes and their dynamics for early warning. Through policy and management interventions, we can promote or prevent tipping, reduce risks, and enhance sustainability.
In this presentation, we examine the evolution and tipping dynamics of typical coastal zones like the Baltic Sea and the Bohai Sea. Using complex system theory, human - Earth coupling, and resilience management, we analyze the dynamic behaviors and cascading processes when the subsystem is near or at the critical state due to control parameter intensity changes. This emphasizes integrating natural and social sciences and new technologies, identifying critical transitions, and proposing strategies to boost coastal system resilience. These include developing advanced observation networks, coupled regional earth system models, and using AI and digital twins to detect early - warning signals and manage tipping processes adaptively.
