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Roger Weller, geology instructor

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Icebergs
by Kim Nason
Physical Geology
Spring 2014
 

 

 

Glaciers vs. Icebergs, the Jakobshavn Glacier, and the Titanic
 

        We all know that ice is a beautiful and dangerous element (especially thanks to the new Disney movie Frozen 2013), but is there some ice that is more dangerous than other forms? For example, what is an iceberg compared to a glacier?
 

Glaciers are monsters of the ice world formed by the incessant deposition of snow over time that compact on itself, turning into massive, thick sheets of ice. On the other hand, icebergs are merely chunks of glaciers that break off and float out to sea, paling in comparison to the size of glaciers, but much more dangerous due to mobility.
 

(http://www.nasa.gov/centers/goddard/news/topstory/2004/0913larsen.html)


     The reason icebergs are so much more dangerous? Icebergs float out into the ocean via currents, but most of the mass is underwater, as the density of the ice causes it to sink low into the water, leaving only the tip visible (about 10% of the iceberg). Even the smaller icebergs (known as growlers or bergy bits, depending on size) can do catastrophic damage to a ship.
 

(http://www.accuweather.com/en/weather-news/icebergs-still-a-threat-100-ye/63626)
 

Here is a simple chart highlighting the differences between glaciers and icebergs.
 

Glaciers                                             Icebergs

Formation

Incessant deposition of snow

Breaking off from glacier

Size

Larger

Smaller

Location

Mountains, valleys and polar regions

Fresh or sea water beds

Exposure

Entirely above water level

10% above water level

Variants

Limited

Several

Formation

A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation (melting) over many years, often centuries.

Ice bergs are formed from breaking off glaciers.

(http://www.diffen.com/difference/Glacier_vs_Iceberg)
 

            Perhaps one of the most infamous and well-known icebergs of all time is the one that sank the RMS Titanic. The ship sank after it scraped along the side and part of the underwater mass of an iceberg on April 14, 1912. Scientists have now traced where this famous iceberg originated. The iceberg has been traced back to the Jakobshavn Glacier in Greenland. This makes sense, since 85% of the Earth’s icebergs originate in Greenland.

 

(http://www.rmwexplorations.com/theories.htm)

 

            This iceberg would’ve begun forming 15,000 years before the Titanic was even built, as a snowflake falling and compacting to form the Jakobshavn Glacier. Once the iceberg broke off (in approximately 1909), it would’ve taken the glacier (approximately a mile long) slightly more than a year to travel down the 40 mile fjord and get picked up by the powerful west Greenland current. “The relentless jostling of other bergs on this journey would have battered and eroded it, reducing it to half its birth weight.” (BBC) By 1911, the iceberg would have been caught by the west Greenland current, traveled along the Canadian coast then down into the Atlantic Ocean, right into the path of the Titanic.
 

(http://blogs.scientificamerican.com/history-of-geology/2012/04/14/the-science-behind-the-iceberg-that-sank-titanic/)

 

            While the Titanic was indeed a tragedy, don’t think you’ve heard the last of the Jakobshavn glacier. In the last three years, the glacier has steadily been firing many more icebergs into the ocean at an unprecedented rate and accelerating. With the water warming up, there is more flow beneath the glaciers, pushing them father out to sea at incredible rates. By pushing the glaciers out to sea, part of the ice now hangs over deep water, leaving little resistance to calving icebergs.
 

(http://www.buffalo.edu/news/releases/2011/07/12722.html)
 

            With that being said, the accelerated release of ice from Jakobshavn makes it the fastest-moving major glacier in the world. This also means it has the fastest recorded flow rate ever for any glacier or ice stream in Greenland and Antarctica. Why is this relevant? With the excessive amount of icebergs being released into the ocean and melting, Jakobshavn has affected sea level quite drastically. Between 200 and 2010, the Jakobshavn glacier melted enough to add an entire millimeter (about the width of a dime) to sea level. If Jakobshavn and the other glaciers in Greenland continue to melt at this rate (or heaven forbid accelerate this rate) they will be adding about three inches of water to sea level every century. With this news or a rising sea level, one can’t help but think, “Maybe the glacier that killed the Titanic with one of its icebergs is blood thirsty again.”
 

 

References:

http://www.accuweather.com/en/weather-news/icebergs-still-a-threat-100-ye/63626

 

http://www.bbc.co.uk/history/topics/iceberg_sank_titanic

 

http://blogs.scientificamerican.com/history-of-geology/2012/04/14/the-science-behind-the-iceberg-that-sank-titanic/

 

http://www.buffalo.edu/news/releases/2011/07/12722.html

 

http://www.diffen.com/difference/Glacier_vs_Iceberg

 

http://www.npr.org/blogs/thetwo-way/2014/02/03/271148468/iceberg-blamed-for-sinking-titanic-pushing-more-ice-into-ocean

 

http://sploid.gizmodo.com/the-glacier-that-killed-the-titanic-is-firing-icebergs-1515009882