Scientists have traced the likely origins of the iceberg that sank the Titanic .
Using observations taken in 1912 and earlier, and modern data about ocean currents and winds, experts believe the iceberg that sank the passenger liner on its maiden voyage probably originated in a small cluster of glaciers in southwest Greenland with snow that fell up to 100,000 years ago.
“We have a computer model for calculating the paths of icebergs in any given year,” said Grant Bigg, professor of earth system science at Sheffield University, who will present his findings at the Cambridge Science Festival, which begins tomorrow. “We take what we know about ocean currents, then add in meteorological readings for that year to calculate the prevailing winds. Applying those techniques to 1912 points to the iceberg coming from around Qassimiut on Greenland’s southwest coast.”
Bigg found the iceberg was huge. When the Titanic sank, killing 1,517 people, it was estimated at 400ft long and projecting up to 100ft above the water, giving it an approximate mass of 1.5m tonnes. However, the collision happened at a latitude of 41 degrees north, meaning it had floated from Greenland to a point further south than Cornwall, and must have been melting into the sea for months beforehand. Based on the shrinkage of similar icebergs, Bigg estimates it began life 1,700ft long , with a mass of 75m tonnes.
Icebergs form when snow is compacted into ice by more snow falling on top of it. While solid, such ice can flow slowly downhill, forming glaciers that break up on hitting the sea. Bigg has calculated that the snow which formed the Titanic iceberg was up to 100,000 years old.
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The loss of the Titanic led to the creation in 1914 of the International Ice Patrol, run by the United States Coast Guard, but co-funded by Britain and other countries, to count and track icebergs. It found that, on an annual average, 300 icebergs with the potential to sink ships floated past the 48-degree north line of latitude, which roughly marks the start of shipping lanes. The number varied from zero some years to 2,300 in 1983.
Bigg’s research suggests 1912 was a bad year, with icebergs reported floating much further south than normal. In his new book, Icebergs, he writes: “The presence of extensive ice was widely reported prior to and following the collision.”
Why the number reaching shipping lanes should vary so much from year to year is unclear, because so many factors — wind direction, sea currents and temperature changes — are involved. One idea is that the Titanic iceberg broke from its glacier in 1908 when a mild winter accelerated melting and floated south during the much colder winter of 1911-12.
What is certain is that icebergs remain a threat. In 2007 the Explorer, a cruise ship, sank in Antarctica’s Weddell Sea after an iceberg strike. The threat may be growing, with the average number of north Atlantic icebergs reaching shipping areas rising to 500 a year over the past two decades. In 2014, 1,500 were recorded.
Andrew Fleming, remote sensing manager for the British Antarctic Survey, who uses satellites to track icebergs in the Arctic and Antarctic, said: “The past 10 to 20 years have seen a steady overall increase in the number of icebergs.”