Glaciers, natural ice formations found in polar and high mountain regions, are crucial reservoirs of freshwater on Earth.

They form as snow accumulates over many years, undergoing compression, recrystallization, and refreezing processes. Once granular snow transforms into glacier ice, it exhibits plasticity, allowing it to flow and slide under the influence of gravity.

The International Glacier Inventory defines glaciers as ice bodies exceeding 0.1 square kilometers. However, their formation requires adequate solid precipitation, including snow, fog, and hail. Glaciers require a specific altitude and less steep terrain in mountainous areas, as excessive slope steepness prevents snow accumulation.

The transformation from granular snow to dense ice occurs rapidly near the melting point and more slowly under sub-zero temperatures. Initially, glacier ice appears milky white but becomes thicker, harder, and translucent over time, taking on a crystal-like blue hue.

Glaciers cover approximately 11% of the Earth's land area, with nearly 80% of freshwater resources stored within them. However, the directly usable fraction is minimal. About 97% of glaciers are concentrated in the Antarctic and Greenland ice sheets, which significantly impact sea level fluctuations.

Melting glaciers and ice caps contributed to an annual average sea level rise of 0.2 to 0.4 millimeters in the 20th century. While the Greenland ice sheet contributed slightly, the Antarctic ice sheet's contribution was effectively neutral. Melting mountain glaciers and ice caps substantially impacted sea levels and increased the number of sheets.

With ongoing global warming, glacier melting intensifies. Rising temperatures within glaciers can accelerate ice flow, potentially leading to disintegration. The West Antarctic Ice Sheet is particularly vulnerable due to its location on islands rather than continuous landmasses.

If the entire Antarctic ice sheet were to melt, it could raise global sea levels by approximately 65 meters. This would have devastating consequences, submerging vast coastal areas and significantly reducing habitable land for human survival.

Glaciers are vital freshwater resources and play a significant role in regulating sea levels. Their loss due to global warming severely threatens coastal regions and the global population, emphasizing the importance of addressing climate change to mitigate these risks.