The ice-albedo feedback is one of the most important amplification mechanisms in climate change. Ice and snow have high albedo (0.6–0.9) and reflect most solar radiation. When they melt, they expose dark ocean (albedo 0.06) or land (albedo 0.1–0.3) that absorbs much more heat.
In the Arctic
This feedback explains amplified Arctic warming: the Arctic warms 2–4 times faster than the global average. Sea ice is declining by ~13% per decade each summer. Loss of summer Arctic sea ice (projected for 2030–2050) will remove much of this reflective albedo, accelerating global warming.