Hydrosphere – Distribution of Earth’s Water Where is the dominant percentage of the planet’s water volume stored within the hydrosphere?

Introduction / Context:
Understanding how Earth’s water is distributed helps explain climate, ocean circulation, freshwater scarcity, and sea-level change. The hydrosphere includes all water reservoirs: oceans, ice, groundwater, surface water, atmospheric moisture, and biological water.

Given Data / Assumptions:

• We compare major reservoirs by volume.
• “Dominant percentage” means the overwhelmingly largest share.
• Approximate textbook proportions suffice for this question.

Concept / Approach:
Oceans and seas contain by far the largest share of Earth’s water (about 96–97%). Ice sheets and glaciers account for most of the remaining freshwater by volume, with groundwater a significant but smaller fraction; surface freshwater (lakes/rivers) and atmospheric water vapor are tiny by comparison. Therefore the correct choice is “oceans and seas.”

Step-by-Step Solution:

Verification / Alternative check:
Any standard Earth science chart of the hydrosphere shows oceans containing roughly 1.35 billion km^3 of water, dwarfing other stores. This empirical fact validates the answer.

Why Other Options Are Wrong:

• Groundwater, rivers and streams: Groundwater is significant, but total is far below ocean volume; rivers/streams are minuscule.
• Glaciers and ice sheets: Large freshwater store, yet still only a few percent of total water.
• Freshwater lakes and water vapours: Both are small fractions of global water.

Common Pitfalls:
Confusing “most freshwater” (ice sheets) with “most total water” (oceans). The question asks about the overall hydrosphere, not only freshwater.

Final Answer:
oceans and seas