Acoording to the National Snow & Ice Data Center (NSIDC), icebergs can develop into a variety of shapes as they break apart. (Photo Ted Scambos, NSIDC) By Alex Sosnowski, Expert Senior Meteorologist
Apr 10, 2012; 12:05 PM ET
One hundred years after the RMS Titanic foundered in icy waters 375 miles south of Newfoundland, the dangers of vessels striking an iceberg continue.Shipboard radar, satellite photos, global positioning systems (GPS) and aircraft patrols have made the North Atlantic safer now than it was during the early 1900s.
However, despite improvements in detection methods and more accurate ship positions, as well as trending warmer seas melting the icebergs faster, ships continue to have close encounters with these frozen, floating objects.
According to the BBC, between 1980 and 2005 there have been 57 incidents with vessels involving icebergs.
The greatest danger from icebergs today is from much smaller objects than portrayed here. It is believed that the RMS Titanic struck a small- to medium-sized iceberg. Graphic by Al Blasko, AccuWeather.com
On Nov. 23, 2007, the MS Explorer struck submerged ice, believed to be part of an iceberg, and sank in the Southern Ocean.
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While the number of icebergs tends to vary greatly from year to year there are, on average, 15,000 icebergs born annually. Interestingly, in some years there can be up to 40,000 icebergs calved. In the Northern Hemisphere, between 1 and 2 percent of all the icebergs reach southward to 48 degrees North.
The most significant problem facing shipping and detection measures has to do with the size of the icebergs.
In the Northern Hemisphere, most of the icebergs are calved from West Greenland glaciers. Calving occurs when pieces of the ice break off and float into the sea, or when a large iceberg breaks up into a smaller one. From Greenland, the surviving icebergs eventually drift southward via the Labrador Current into the northwestern Atlantic Ocean.
Image appears courtesy of the United States Coast Guard.
In the northwestern Atlantic, as the cold Labrador current interacts with the warm Gulf Stream, eddies form. These swirls of water, combined with surface winds can transport the icebergs farther south (and east) on occasion.
In the Southern Hemisphere, the calving occurs around Antarctica from ice shelves and glaciers. Similarly wind and currents transport the icebergs away from the South Pole continent.
According to Dr. Peter Wadhams, "There are more icebergs now than there were in 1912."
Wadhams is Professor of Ocean Physics, Department of Applied Mathematics and Theoretical Physics, at the University of Cambridge, United Kingdom.
"During the past 10 years, the downhill flow rate of the Greenland glaciers has doubled in speed and is contributing to a larger number of icebergs being calved," Wadhams said.
Based on a study done by the Geological Survey of Denmark and Greenland, which tracked calving of Greenland icebergs as far back as 1890, the calving rate in recent years was matched only during a period during the 1930s.
Wadhams stated that warmer seas were accelerating the melting process, but at the same time are calving smaller bergs out of the larger ones.
The smaller icebergs are known as growlers (less than 3.3 feet high by less than 16 feet long) and bergy bits (3.3 to 16 feet high by 16 to 49 feet long).
"The growlers and bergy bits are difficult to detect by radar and satellite, yet are still capable of damaging or sinking a ship. Since there are more icebergs and they are melting faster, we can expect a bigger population of growlers and berg bits, so more danger to shipping," Wadhams explained.
There continues to be more evidence that ocean temperatures have been rising and for a longer period of time than once thought.
Ocean water warming was believed to have initiated about 50 years ago, but is now believed to have begun over 100 years ago according to a study done by the Scripps Institution of Oceanography at UC San Diego.
According to a National Aeronautics and Space Administration (NASA) funded 2006 study that spanned 20 years, the combined loss of mountain glaciers and ice caps averaged 402 gigatonnes per year.
The retreat of Arctic sea ice has opened new, shorter fuel-saving routes for shipping during the warmer months of the year. Sea ice is different than icebergs and forms as sea surface water freezes.
In addition, a number of vessels, including super freighters are ripping along routes through the Southern Ocean, avoiding the log jam of vessels in the Panama and Suez canals.
However, since there are more ships venturing into polar waters these days, the risk of collision from vessels striking the larger number of growlers or bergy bits out there also increases.
Not only are there dangers to ships, but also petroleum platforms in northern and southern latitudes.
So while research, technology and patrols over the past 100 years have made the sea less perilous in terms of striking the big icebergs, significant risks continue for coming in contact with the smaller, yet potentially destructive growlers and bergy bits.
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In the months that followed after the Titanic sank near Newfoundland in 1912, the United States and 12 other nations formed the International Ice Patrol to warn ships of icebergs in the North Atlantic. This was joined by aircraft patrols in the 1930s, radar after World War II and improved satellite resolution and patrols during the latter half of the 20th century. The U.S. National Ice Center currently uses satellites to track large icebergs near Antarctica.
This image made from a webcam on board the MS Nordnorge shows the the Liberian-flagged M/S Explorer listing in Antarctic waters, Friday, Nov. 23, 2007. More than 150 passengers and crew took to lifeboats in Antarctic waters. (AP Photo)
The RMS Titantic foundered, bow first, on April 15, 1912. Of the 2,224 passengers, 1,514 drowned or succumbed to hypothermia in freezing waters. The wreck lies in 12,415 feet of water.
Observations on board Titanic indicated a 10 degree (F) drop in sea surface temperatures (from the lower 40s to the lower 30s) in two hours during the early evening of the 14th. This supports the idea that the Titanic passed from relatively warm Gulf Stream waters to the colder influence of the Labrador Current.
The water temperature in Titanic's vicinity at the time of the collision late in the evening of the 14th was said to be in the upper 20s. Sea water freezes at a lower temperature (approximately 28.4 degrees F) than freshwater.
The extremely frigid waters expedited hypothermia among the mass of people adrift. Most died within minutes after plunging into the sea.
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