Global mean sea level can rise through changes in ocean volume at fixed mass and through additions of ocean mass. Local relative sea level additionally depends on ocean circulation, gravity and vertical motion of the land. Floating sea ice has already displaced seawater, so its melt has a much smaller direct sea-level effect than transfer of grounded land ice into the ocean.
With positive freshwater runoff , net sea ice melt and precipitation , and evaporation loss , the ocean water-mass budget is . With salt-free ice and fixed total dissolved salt mass, mean salinity satisfies . Gross regional ice melt must not be substituted for net global melt without accounting for ice formation elsewhere and the averaging period.
Eustatic sea level change is a change in global sea level associated with changes of ocean water amount or ocean-basin capacity. For contemporary climate budgets the relevant contribution is principally transfer of water between land and ocean, including melting grounded ice and changes in terrestrial water storage. It is distinct from steric sea level change.
Steric sea level change results from changes of seawater mass density at fixed ocean mass. To first order, thermal expansion gives ; changes in salinity give a halosteric contribution. The reference column, pressure and equation of state must be specified.
Thermosteric sea level change is the thermal expansion part of steric sea level change. For a uniform layer of depth , conservation of mass gives , hence .
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Sea level rise refers to the increase in the average level of the world's oceans due to various factors, primarily driven by climate change. This phenomenon can have significant impacts on coastal environments, communities, and ecosystems. The main contributors to sea level rise include: 1. **Thermal Expansion**: As ocean water warms, it expands, contributing to rising sea levels. 2. **Melting Glaciers and Ice Sheets**: The melting of glaciers and polar ice sheets (e.g.