The Earth is a dynamic, self-regulating system, and forever changing. The changes that take place in each of the spheres of the Earth impact the other, connected spheres. There are complex feedback mechanisms that work to maintain the balanced functions of the planet. As we explore the topic of sea level change, the importance of these feedback mechanisms become clear. It is hard to isolate a single cause of sea level rise or fall, as all are connected and may be occurring simultaneously. It is worth remembering some principles you may have learned in your pre-college days, such as the water cycle, rock cycle, plate tectonics, and how heating and cooling affect matter.
Global or eustatic sea level can oscillate due to changes in the volume of water present within the ocean basins relative to storage of that water on land. Short-term sea level change can be driven by sudden tectonic events (e.g., earthquake-induced subsidence/uplift), and tidal processes, but sea level change on the scale of decades to 1000s of years is primarily driven by changes in the Earth's climate system that can be influenced by both intrinsic and extrinsic phenomena.