4.1.3—Hydrological cycle stores
- Syllabus
- First assessment 2026
- Objective
- 4.1.3
- Level
- HL
See the Scale Gap between Water Stores
Oceans hold about 96.5% of Earth’s water; ice and groundwater are the next large stores, while rivers, lakes, air and organisms are tiny fractions.
Use the order of magnitude to interpret access: global abundance does not mean freshwater is easy to reach, clean or renew quickly.
A lake may be vital locally but still contain only a minute share of global water compared with the ocean.
Most water is saline or locked in slow stores; accessible freshwater is a small, uneven fraction.
A percentage of global water is not a measure of local availability or sustainable supply.