Chapter 01 · Climate & transitionClimate & Greenhouse Gas Emissions
Albedo effect
Definition
Albedo is the fraction of incoming sunlight that a surface reflects, ranging from 0 (a perfectly black, absorbing surface) to 1 (a perfect reflector). Fresh snow reflects up to 90% of sunlight and clouds 30–90%, while ocean surfaces reflect less than 10%. The "albedo effect" refers to the influence of this reflectivity on Earth's energy balance and temperature.
References
Definition and reflectivity values; albedo-climate feedback loop; Arctic amplification ~4×; drivers (ice loss, clouds, vegetation, permafrost).
Scientific context for climate feedbacks and Earth's energy imbalance.
Overview
What it means
Because dark surfaces absorb more solar energy, any shift from bright to dark surfaces warms the planet. Warming shrinks reflective snow, sea ice and glaciers, exposing darker ocean and land, which absorb more heat and cause further warming — the albedo-climate feedback loop. Cloud thinning, vegetation shifts and darkening from permafrost thaw add to the effect.
How it is used
Albedo appears in climate models as a key feedback and in assessments of geoengineering proposals that would artificially raise reflectivity. It also matters practically: light-coloured "cool roofs" and pavements are used to reduce urban heat, and land-use decisions (such as afforestation at high latitudes) are assessed partly for their albedo effects.
Why it matters
Albedo loss is one reason the Arctic has warmed nearly four times faster than the global average since 1979. It contributes to Earth's accelerating energy imbalance, meaning part of today's warming momentum comes from the planet simply becoming less reflective.