I think there was a little blurb in the news the other day that mentioned that an iceberg the size of Delaware has been spotted and is being tracked in the Antarctic. I thought to myself “Delaware, holy shit, that’s huge!” Well, was I in for a surprise when I did a little research. Here’s some facts and figures regarding the lifecycle of icebergs that I hope you find it as interesting as I did.
Where do they come from?
The majority of the icebergs in the North Atlantic come from about 100 iceberg producing glaciers along the coast of Greenland and a couple originate in the Eastern Canadian Arctic Islands. The glaciers of western Greenland are where 90% of Newfoundland's icebergs originate and are amongst the fastest moving in the world. The icebergs that are seen off Newfoundland are carried south in the Labrador current.
How many are there?
About 40,000 medium to large sized icebergs calve each year in Greenland and about 1 to 2% (400-800) of those make it as far south as 48o north latitude (St. John's). These numbers vary greatly from year to year and season to season. The best time to spot them off Newfoundland is in the spring and early summer
How old are they?
The ones that make it to the east coast of Newfoundland probably calved from a glacier over a year before. Most of the time they spend a year or more in cold arctic bays melting slowly (or not at all in winter) until eventually passing through the Davis Strait and into the Labrador current. They usually don’t make it one year when heading south of this point. The ice itself has been estimated to be over 15,000 years old.
How do they form?
Glaciers form on land as a result of a net accumulation of snow over thousands of years. Successive layers compress earlier accumulations until, at depths below 60 to 70 meters, glacial ice is formed. Glaciers "flow" or "creep" outward under their own weight like a viscous
fluid. When the edge of a glacier advances into the ocean the pieces that break off are what icebergs
How fast do they move?
The average drift speed of icebergs off the north east coast of Newfoundland is around 0.2 m/s (0.7km/h). Iceberg drift speed is actually influenced by many factors including iceberg size and shape, currents, waves and wind. Speeds greater than 1 m/s (3.6 km/h) have been observed, as have stationary non-grounded bergs. Given all of these factors, its hard to predict what path your average iceberg might take. The actual distance traveled by a berg may be two or three times the straight line distance over a week or so
So where do they go?
For the most part, before they completely deteriorate, they travel many thousands of kilometers. Originating at around 75o north latitude in Baffin Bay, an iceberg may travel up to 4,000 km south to around 40° north latitude (800 km south of St. John's). Extremely unusual sightings in Bermuda and Ireland have occurred well outside of this normal limit.
Why are they mostly white?
They’re mostly white because the ice is full of air bubbles. The bubble surfaces reflect white light giving them an overall white appearance. Ice that is bubble free has a blue tint for the same reasons that the sky appears blue.
How much it is below water?
The “tip of the iceberg" can be explained as follows: Icebergs float because the density of ice (around 900 kg per cubic meter) is lower than that of seawater (around 1025 kg per cubic meter). The ratio of these densities tells us that 7/8 of the iceberg's mass must be below water. Usually they are 20% to 30% longer under the water than above .
How do icebergs break up?
They melt, next question…Oops, hold on, while melting they might fracture into many pieces which can create trails or halos of smaller floating pieces. Usually icebergs melt the fastest at the waterline by the action of waves . Melt and breakup rates change with water and temperature. For instance a large berg may take 90 days to fully deteriorate in water temperatures around 0 Celsius whereas the same berg may only last 11 days in 10 Celsius water.
How much do they weigh?
Icebergs off the coast of Newfoundland and Labrador range in size from massive tabular and blocky bergs in excess of several million tons to small bergs weighing 1% of this. The average iceberg weight for the Grand Banks
area is one to two hundred thousand tons, and is about the size of a cubic 15 story building.
What shapes do they come in?
You name it, a large variety of shapes result from the deterioration process of icebergs. Despite the fact that no two icebergs are the same, they do have certain characteristics used to describe them. The terms tabular, blocky, wedge, dome, pinnacle, and drydock are commonly used.
Can you tow an iceberg?
Hell yes, towing icebergs was first demonstrated in 1971 in Newfoundland. It is now a common practice in the management of icebergs for the offshore oil industry. In Newfoundland, the ice from an iceberg is being "harvested" for bottled water and vodka production. More products are on the way.
What is the largest iceberg recorded?
The largest Northern Hemisphere iceberg on record was encountered near Baffin Island in 1882. It was 13 km long, 6 km wide and had a height above water of about 20 m. The mass of that iceberg was in excess of 9 billion tons - enough water for everyone, in the world to drink a liter a day for over 4 years. Think that’s big, icebergs from Antarctica may be many times larger. In 1987 an iceberg with an area of 6350 square kilometers broke from the Ross Ice Shelf. That baby had a mass of around 1.4 trillion tons and could have supplied everyone in the world with 240 tons of pure drinking water.
How stable are they?
They’re not. This is due to their random shape and the unpredictability of melting and breakup,. The tabular bergs are considered the most stable whereas domed and wedge shaped bergs may roll completely over in seconds without any apparent cause.
Are they salty?
No. Icebergs are comprised of pure fresh water. There may be some dust embedded in the ice and salt water may be on the surface but it does not penetrate the ice. Iceberg ice is quite safe to consume.