Glacier calving is the process by which blocks of ice break off (calve) from the terminus of a glacier or ice shelf, generating displacement waves and sometimes localized tsunamis when large volumes hit the water. Because glacial ice is slightly less dense than seawater (roughly 900 kg/m³ versus 1025 kg/m³), calved blocks float as icebergs while the impact and subsequent buoyant rebound send powerful ripples and splash outward. Calving accounts for a substantial share of mass loss from marine-terminating glaciers and ice shelves, and is a major contributor to global sea level rise as polar ice sheets thin. The cracking and fracturing of ice under stress often produces loud low-frequency booms and cracks nicknamed "white thunder" by people living near glaciers, audible seconds before the visible collapse due to the delay between fracture and sound travel.

• Large Antarctic and Greenland calving events can release ice blocks exceeding 1 million tons in a single episode
• Active tidewater glacier ice cliffs commonly stand 30-90 m (100-300 ft) tall above the waterline
• Ice density (~900 kg/m³) is about 88% of seawater density (~1025 kg/m³), which is why roughly 90% of an iceberg stays submerged
• Large calving impacts can generate local waves several meters high near the calving front, occasionally described as glacier "tsunamis"
• Fast-flowing tidewater glaciers (e.g., parts of Greenland) can calve multiple times per day during peak summer melt season
• Calving noise, "white thunder," can register over 100 dB near the source and is used by researchers to help estimate calving rates
• Glacier and ice-sheet mass loss (calving plus melt) currently contributes roughly 1 mm/year to global sea level rise
• Some Antarctic ice shelf calving events have produced tabular icebergs larger than 1,000 km²