Ice–albedo feedback

A positive climate feedback in which melting snow and ice expose darker surfaces, increasing absorbed sunlight and causing further warming and ice loss.

Albedo: The fraction of incoming radiation that a surface reflects rather than absorbs. The feedback operates by changing the reflectivity of snow, ice, ocean, and land.
Earth's energy budget: The balance between energy Earth receives from the Sun and energy it returns to space. Changes in absorbed sunlight alter this planetary balance.
Climate models: Computer representations of Earth's climate system used to simulate past, present, and future conditions. Models calculate surface reflectivity changes to estimate feedback strength and future warming.
Cloud masking: The obscuring of a surface by clouds in satellite observations or radiative measurements. Clouds complicate estimates of how much changing ice cover alters reflected sunlight.
Arctic Ocean: The ocean surrounding the North Pole, bordered by Eurasia and North America. Reduced sea ice allows greater solar absorption in its surface waters during sunlit seasons.
Sea ice: Frozen seawater that forms and persists at the ocean surface. Its bright cover reflects sunlight; retreat exposes darker ocean that absorbs more energy.
Shortwave radiation: Electromagnetic radiation from the Sun, concentrated at shorter wavelengths than terrestrial heat radiation. Surface albedo controls how much incoming solar shortwave energy is absorbed.
Satellite remote sensing: The collection of information about Earth from instruments carried by satellites. Satellite records track changing ice extent and surface reflectance over broad regions.
Snow grain growth: The enlargement of snow crystals over time through metamorphic processes. Larger grains reduce snow reflectivity, making surface aging another source of albedo change.
Seasonal sea-ice cycle: The annual pattern of sea-ice growth in colder months and retreat in warmer months. Earlier melt and later freeze can lengthen the period of open-water solar absorption.

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