Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by Kim Nason
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
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
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.
Here is a simple chart highlighting the differences between glaciers and
Incessant deposition of snow
Breaking off from glacier
Mountains, valleys and polar regions
Fresh or sea water beds
Entirely above water level
10% above water level
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.
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.
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.
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.
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.
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
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