- CNN's Fred Pleitgen joins Danish meteorologists as they chart the passage of Greenland icebergs
- More icebergs have been observed in recent years but experts unsure of long-term trend
- Observers fly missions three times a week before filing reports on dangerous ice
- Ice Patrol founded after "Greenlandic Titanic" sank off the island's coast in 1959 killing all crew and passengers
Every year, we hear stories of global warming advancing and the effects that has on the earth's climate patterns.
One phenomenon that is often used to illustrate ice melt in the Arctic is giant icebergs, often the size of whole towns or even small countries, breaking off the ice shield and drifting south.
In reality, icebergs constantly break off both the arctic ice shield and Greenland's inland glaciers, a process that scientists call calving.
To find out whether that process is accelerating a CNN crew traveled to southern Greenland, to the small village Narsarsuaq, where the Danish Meteorological Institute (DMI) keep a unique unit of experts.
They are called the Ice Patrol and the unit consists of ship navigators and pilots who fly across the south of this vast island to monitor the movement of icebergs, to prevent collisions with cargo ships navigating in the waters around Greenland.
"We keep an eye out for icebergs that are bunched together in narrow waterways," said ice observer Jane Robertson on an airborne mission around the southern tip of Greenland. While big icebergs can pose a threat to vessels going through here, surprisingly it is smaller ice pieces that are even more dangerous.
"The smaller icebergs are much harder to detect," Robertson said as she was surveying the ice with her binoculars, "especially if the icebergs have been traveling in the water a long time they become almost colorless and nearly invisible in the ocean."
Flying over the majestic landscapes of this part of Greenland, observers see a huge amount of icebergs, some almost the size of aircraft carriers and several stories tall, others shaped in a distinctive blue coloring because the air has been pressed out of the ice in its glacial journey.
Some experts believe that the glaciers in Greenland are calving at a higher rate as temperatures rise, but the ice observers say their observations are not long term enough to speak of a general trend.
"In the past two years there have been more icebergs here," Robertson says, "but then again in the years before there were a lot fewer so it really varies from year to years."
However, other observers point to the fact that Greenland's glaciers have been receding for years, pointing to increased ice melt in the polar region. But even on fairly clear days it takes an experienced captain to navigate a ship through the waters around Greenland.
Robertson is also an officer on the Royal Arctic Line, Greenland's own shipping company and says it takes years to understand the challenges involved sailing in Greenland.
"When you encounter masses of icebergs you can either try and go through it or you can go around it," Robertson said. "In most cases the captain will usually try and go around it if he can because no matter how slow you go and how careful you are there will always be damage to the ship and then the weather can get much worse very quickly and you don't want to be in a field of icebergs if it does."
Her experience as a ship's navigator make her so valuable as an ice observer for the DMI, but the everyone in the crew needs to be at the top of their game.
Karsten Andsbjerg pilots the helicopter through the fjords and hills in this extremely rugged terrain. A difficult task as he often deals with severe weather while having to make the ride smooth enough for the observers to do their job.
"Yeah, there are some pretty heavy and gusty winds here," Andsbjerg said shortly after landing at a Danish weather outpost right at the southern tip of Greenland.
"The other thing is that the weather changes so quickly here, you always have to call ahead to all the airfields and weather stations and keep yourself updated. Otherwise you can be in severe weather in no time."
The observers fly missions three times a week if the weather permits. Afterward they file reports on the location of dangerous ice clusters with photos that show vessels what they are in four if they try to get through. The Ice Patrol's reports are vital and may have already saved lives.
The unit was founded after a ship sank off the coast of Greenland in 1959, killing all crew and passengers on board. The MS Hans Hedtoft disaster is known as the "Greenlandic Titanic" in this part of the world.
Eydun Simonsen, the chief ice observer during CNN's stay with the unit said: "Just like the Titanic, it was her maiden voyage. To this day we don't know exactly what happened, but we do know that she hit an ice berg and sank with all souls on board. She did manage to send an SOS and later some rescue equipment was recovered."
There hasn't been a major incident in the waters off Greenland since the ice patrol was founded. Better satellite images and more advanced ships will also have played a role in this improved track record, but there is no doubt that captains navigating the cold and often treacherous water of the Arctic value the detailed and up to date information the observers provide.