Definition of an Iceberg
An iceberg is a large piece of freshwater ice that has broken off from a glacier or an ice shelf and is floating freely in open water. They vary greatly in size and shape, from small chunks to massive formations that can be hundreds of kilometers long, and are typically found in the polar regions of the Earth.
How Icebergs Form and Their Origins
Icebergs form through a process called 'calving,' where large fragments of ice detach from the edge of a glacier or an ice shelf. This often occurs when ice flows into warmer waters or when tidal forces and waves weaken the ice front. The ice that forms an iceberg originated as compacted snow that solidified into glacial ice over centuries or millennia.
Key Characteristics and the 'Tip of the Iceberg' Principle
A defining characteristic of an iceberg is that only about one-tenth of its total mass is visible above the waterline, a phenomenon governed by the density difference between ice and seawater. The submerged portion, which can be much larger and irregularly shaped, poses a significant hazard to shipping, giving rise to the idiom 'tip of the iceberg.'
Importance and Environmental Impact of Icebergs
Icebergs play a role in ocean circulation and climate by slowly releasing freshwater and cooling the surrounding ocean as they melt. They can also transport sediments and organisms across oceans. However, their presence is a major navigational concern, and their increasing calving rates are a strong indicator of accelerating climate change and glacial melt.