As icebergs melt in Greenland, scientists need a front-row seat

Melting icebergs are an engine of climate change, but we know surprisingly little about them.

By Daniel Carlson

Icebergs pose a particular challenge for climate scientists. They are simultaneously a key part of the ocean physics driving climate change, and very difficult to collect real-world data on. In most cases, studying actual icebergs in the actual ocean requires traveling to harsh, remote locations to examine a massive piece of ice that could break apart at any minute. This is time consuming, expensive, uncomfortable, and at times dangerous. But it’s extremely important—we need more of this kind of data. That’s why my research has brought me to Greenland, to see and measure melting icebergs first-hand.

Greenland is a new front line for climate research 

With the melting of the Greenland Ice Sheet accelerating in recent years, it’s time to look a little more closely at the icebergs there. Freshwater from melting ice lowers the density of the ocean’s surface waters. This can affect deep water formation that drives large-scale ocean circulation patterns. In short: Where icebergs melt and where that meltwater goes has local, and possibly also global implications. So we need to understand how icebergs drift, and how much of their meltwater is making it out into the ocean. Gathering this important information has meant getting creative, finding low-cost ways to get up close and personal with icebergs.

Greenland’s icebergs aren’t like other icebergs

Due to the cost and effort required to study icebergs in their natural environment in Greenland, satellites and models are often used to study how icebergs melt and drift. Models are an incredibly important tool, but a realistic model of iceberg drift will be difficult to achieve without feeding it with real-world data first.

For one, many models assume “a simplistic iceberg geometry.” In the six months I’ve spent at sea around Greenland, I have yet to see an iceberg with simplistic geometry. What’s more, most models are based on measurements from the Labrador Sea, collected in the 1980s and 1990s. We can’t expect icebergs of Greenland’s fjords, which vary in their complex combinations of shape, size, color, and sediment load, to behave the same way.

This is not a fault of the existing models. It simply highlights the need for regional observations, and I hope to work together with modelers and theoreticians to refine existing iceberg models for use in Greenland.

Daniel Carlson

A front-row seat to melting ice

Physically traveling and spending months at sea has already provided fruitful insights into what makes Greenland’s icebergs tick. The commercial GPS trackers used to study iceberg drift are costly and usually deployed by helicopter, which only adds to the expense. As a result, few icebergs in Greenland have been tracked, especially smaller, less stable icebergs and “bergy bits” in fjords. By building my own low-cost iceberg trackers, which can be tossed atop an iceberg from a boat, I was able to track 18 icebergs near Nuuk over periods of 30-100 days.

I’ve also used aerial drones to create 3D models of the above-water portions of icebergs. These models give insights into their irregularity, and can also be used to estimate mass loss by revisiting the same iceberg several times over the period of a few weeks. The drone imagery has shown that, while scientific literature has focused on icebergs capsizing as a source of energy, they’re much more likely to oscillate as small chunks of ice break off. Oscillation, while less energetic, occurs frequently and could be an important source of mixing in the shallow waters of the fjords.

Thanks to what is essentially a GoPro on a pole, I’ve also been able to look underwater for clues as to which processes are responsible for melting the ice. While crude, this method has been very informative. I’ve been able to see two melting patterns: golfball-like dimpling on vertical surfaces, and large grooves that tend to form on sloped regions or areas with overhangs. The grooves probably form as bubbles travel up the sloping ice, pulling warmer water along with them. Bubble-driven mixing and the increase in surface area accelerate the melting.

The “GoPro on a pole” method has since been brought into the modern age using a small, remotely operated vehicle (ROV) designed by undergraduate engineering students. Images collected by the ROV made it possible to construct 3D models of the iceberg keel. This kind of unmanned robotic platform is ideal for studying icebergs, as they place the human operators a safe distance away from a massive, unstable chunk of ice.

Collecting data will get easier as technology advances

Ideally, technological advances will increase the number of autonomous observational platforms in operation in Greenland, which would allow researchers like me to watch the data roll in from the relative comfort of our office chairs. Of course, that experience won’t come close to being in the front-row seat and sailing past a massive chunk of ice, hearing a gunshot-like crack as it breaks apart.

To learn more about this research, visit Carlson's project on ResearchGate