Final answer:
The holding capacity of ocean basins changes due to eustatic sea level rises, thermal expansion from global warming, and melting ice sheets, which all contribute to rising sea levels.
Step-by-step explanation:
The changes in the holding capacity of the ocean basins or the amount of water in them are primarily a result of eustatic sea level changes, thermal expansion due to global warming, and the melting of ice sheets. Eustatic changes refer to worldwide shifts in sea level caused by the alteration of the volume of water in the oceans, as opposed to ice sheets. Meanwhile, thermal expansion occurs because water decreases in density and expands as it warms, which, given the immense volume of the oceans, can significantly raise sea levels. The melting of glaciers and polar ice caps contributes additional water to the oceans, further increasing sea levels.
Acidification of the oceans, another related phenomenon, results from increased uptake of carbon dioxide from the atmosphere. This acidification can have various ecological consequences but is not a direct cause of the change in ocean basin holding capacity.
Overall, these factors combined are causing an ongoing increase in sea level, which has implications for coastal areas, island nations, and global ecosystems both marine and terrestrial due to the alteration of global water distribution.