The iceberg that sank the “unsinkable” RMS Titanic started its fateful journey with a period of unusually warm, wet weather four years earlier, say scientists.
The finding, by a team at Sheffield University, overturns previous theories that high spring tides or a lack of sunspot activity caused a high number of icebergs in the North Atlantic when the Royal Mail Ship set sail on its maiden voyage.
The Titanic sighted a large iceberg, now thought to mass 2 megatonnes, shortly before midnight on 15 April and officers on the bridge acted quickly to slow her and turn to port while ordering the ship’s watertight compartments sealed. But they could not avoid a collision, and the iceberg buckled some 100 metres along her hull below the waterline. She sank less than three hours later, with only 706 of her 2,224 passengers and crew surviving.
Professor Bigg and Dr David Wilton of Sheffield University’s geography department modeled the way icebergs calve, calculating that the most likely origin for the Titanic’s killer was a fjord on the southwest coast of Greenland.
The year 1912 saw a peak in iceberg activity below the 48th parallel, with 1,038 observed. However, this matches other peaks in the decades before and after. And that was far from the most active period in the 112 years of records available to scientists. Fourteen years had higher totals, five of them in the 1990s, “almost certainly due to global warming,” Professor Bigg said.
The idea that the White Star Line’s giant liner was simply unlucky to have crossed the Atlantic during a particularly dangerous period was floated by Edward Lawrence of Britain’s Meteorological Office in 2000. He suggested that a lull in the 11-year sunspot cycle caused colder seas and more northerly winds that year, which together, which together led to more large bergs in the seas off Newfoundland.
But the Sheffield researches report a low correlation between annual sunspot activity and iceberg count over the years since.
The other astronomical theory was suggested by Texas State University’s Professor Donald Olson and lecturer Russell Doescher, along with Roger Sinnott, a senior contributing editor at Sky & Telescope magazine, in 2012, the centennial of the tragedy. They argued that a greater than usual range of tides caused by the Moon coming particularly close to the Earth in the preceding January had put extra stress on Greenland’s glaciers.
However, Bigg and Wilton note that no similar lunar approaches occur in any of the other years with high iceberg counts.
With those two hypotheses out of the way, they looked for other, more complex factors, including the Greenland ice sheet’s surface mass balance. This measures snowfall, which adds to the mass of glaciers during winter, and melting, which weakens them structurally in the summer.
They found a high correlation between this ballance and high iceberg counts four years later.
“The iceberg risk to the Titanic is likely to have predominantly developed around 1908, when a moderately warm and wet year over Greenland produced enhanced snow accumulation,” they say in their paper for Weather, a journal of the Royal Meteorological Society. “We believe that this gradually soaked through cracks in the ice sheet and accumulated around its margins, which probably led to enhanced short-term outlet glacier sliding, with resulting enhanced calving.”