Over the past 100 years, global sea level is estimated to have risen by 10–25…

Concept

Global mean sea level changes through two broad mechanisms: warming changes the volume of existing seawater, while transfers from land add or remove water mass. A contribution is compared by its estimated amount over the stated century-scale period.

Application

For the historical rise described in the question, the estimated thermal-expansion contribution was larger than the contributions from glacier and ice-cap melting, Greenland ice-sheet thinning, or human-driven terrestrial water-storage change.

Contrast

• Thermal expansion increases ocean volume because warmer seawater is less dense and occupies more space, without adding water mass.

• Glacier and ice-cap melting transfers land-based ice into the ocean and adds water mass, but its estimated century-scale contribution was smaller.

• Greenland ice-sheet thinning adds water from one major ice sheet, but its estimated contribution over the stated period was smaller.

• Terrestrial water-storage change redistributes water through groundwater withdrawal, reservoirs, and related human activity, producing a smaller net contribution.

Result

Thermal expansion of ocean waters made the maximum contribution among the offered mechanisms.