Final answer:
Rising sea levels can cause instability in the ocean due to thermal expansion of water and the addition of glacier meltwater, which can impact shorelines, islands, and ecosystems.
Step-by-step explanation:
One thing that could cause the ocean to become unstable is rising sea levels. This is due to the thermal expansion of water as it warms and the addition of meltwater from glaciers.
Rising sea levels result in the inundation of shorelines, reduction in island size, loss of some islands entirely, and a potential overabundance of salt water. This has serious implications for marine biodiversity, human settlements, and overall environmental stability.
Furthermore, it jeopardizes the freshwater cycle that has provided water to ecosystems for centuries. Risks also include potential habitat destruction and ecological imbalance as the marine environment changes.