Icebergs are present in the Atlantic Ocean, concentrated primarily in the North Atlantic. These massive, floating bodies are composed of freshwater ice that has broken off from a parent glacier or ice shelf. Their presence poses a persistent challenge to maritime traffic transiting the cold northern waters. Their journey into the main shipping lanes is a natural process driven by glacial activity and ocean currents.
Where Atlantic Icebergs Originate
The source of North Atlantic icebergs is the Greenland Ice Sheet. Approximately 90% of the icebergs that drift into the North Atlantic shipping lanes originate from glaciers along the western coast of Greenland. This process begins with calving, where large chunks of ice detach from the seaward terminus of a glacier flowing into the ocean.
Glaciers continuously flow toward the sea, where various forces cause them to fracture. One mechanism is buoyancy-driven calving, where the submerged portion of the glacier lifts and breaks away. Another factor is melting at the waterline, causing the overhanging mass to collapse. The glaciers of Greenland discharge an estimated 12,000 to 15,000 icebergs each year. These newly formed icebergs then begin a slow, multi-year drift, influenced by currents and winds.
The Seasonal Path of Iceberg Alley
Once calved, the icebergs are carried south by the cold Labrador Current, which flows from the Arctic region along the eastern seaboard of Canada. This current transports the ice from Baffin Bay toward the Grand Banks of Newfoundland. The drift from Greenland to Newfoundland can take an average of two to three years.
This region, stretching from Labrador to the southeast coast of Newfoundland, is known as “Iceberg Alley.” Here, the icebergs enter the vicinity of major trans-Atlantic shipping routes, creating a risk for vessel traffic.
The presence of icebergs is highly seasonal, peaking during the spring and early summer months, typically from March through July. This timing results from increased meltwater and stronger current flow following winter. The icebergs’ southern progress is generally halted by the warmer waters of the North Atlantic Current, also known as the Gulf Stream, which causes them to melt.
Tracking and Mitigating Navigational Hazards
The risk that icebergs pose to maritime safety led to the establishment of the International Ice Patrol (IIP) in 1914, following a major shipping disaster. This intergovernmental organization, operated by the United States Coast Guard, monitors the iceberg threat in the North Atlantic. Its mission is to determine the limits of the dangerous ice region and communicate this information to the seafaring community.
Modern tracking relies on a combination of advanced technology and traditional observation methods. The IIP utilizes aerial reconnaissance, flying specialized aircraft such as the HC-130J Super Hercules to visually and electronically survey the ocean. These aerial patrols are supplemented by satellite-based Synthetic Aperture Radar (SAR) imagery, which provides a wide-area, all-weather detection capability for icebergs.
The data collected from aircraft, satellites, and voluntary reports from passing ships are compiled daily to predict the movement and melting rate of the icebergs. The IIP then issues an “Iceberg Limit” bulletin, advising vessels where the safe, ice-free waters are located. This continuous monitoring and warning system has been highly effective; no vessel that has heeded the Patrol’s warning has collided with an iceberg since the organization’s inception.