Which factors contribute to sea level rise?

• A. Thermal expansion of warming seawater and added water from melting glaciers/ice sheets; regional variations due to gravitational and isostatic effects.
• B. Decrease in ocean temperature; increased salinity.
• C. Increased solar radiation alone.
• D. Shrinking ice sheets but no thermal expansion.

Answer: (A)

Sea level rises mainly because seawater expands when it warms and because freshwater from melting land ice adds to the ocean’s total volume. When the ocean heats, its molecules take up more space, so the water level climbs even if the amount of water stayed the same. At the same time, melting glaciers and ice sheets pour fresh water into the oceans, increasing how much water is there. Together these two processes push global sea level higher.

Regional differences come from gravitational and crustal responses. Large ice masses pull ocean water toward them; as those masses shrink, that pull weakens, so nearby seas rise less or even fall slightly, while areas farther away experience greater rise. The crust also moves in response to loading and unloading from ice (isostatic adjustment), which can raise or lower coastlines and change local sea levels.

Other options don’t fit because cooling would reduce expansion, higher salinity doesn’t add extra water, solar radiation alone doesn’t by itself produce a sustained rise, and melting ice without any warming-related expansion would miss a major contributor to sea level increase.