Above: An iceberg floats off King's Point on July 5, 2019 in Newfoundland, Canada. (Johannes Eisele/AFP via Getty Images)
Recent research has confirmed that a changing climate as Earth warms is resulting in a significant increase in the loss of ice from the Greenland Ice Sheet. As summarized by Martin Jeffries (University of Alaska Fairbanks): "As the sea ice and snow cover retreat, we're losing bright, highly reflective surfaces, and increasing the area of darker surfaces—both land and ocean—exposed to sunlight. This increases the capacity to store heat within the Arctic system, which enables more melting—a self-reinforcing cycle."
The most direct connection to that increase in loss of ice is a rise in sea level. Scientists have shown that since 1992, nearly 4 trillion tons of Greenland ice have entered the ocean, equivalent to roughly a centimeter of global sea-level rise. In the 2019 NOAA Arctic Report Card it was noted that the discharge from most regions of Greenland has been approximately steady or declining when averaged over the past decade. In between high discharge rates in 2010-2012 and again in 2019, there was a period of relative stability. This is a very complicated picture, and more research is needed to determine the complex roles that melting ice and iceberg calving play in the overall loss of ice from the largest island in the world.
Other research suggests that melting sea ice and icebergs could play another very important role in climate change. It’s a complicated dance that is explained in a writeup by the University Corporation for Atmospheric Research. The dance begins with ocean currents, where water moves through the Atlantic as part of the global thermohaline circulation, also known as the global ocean conveyor belt. The thermohaline circulation in the Atlantic plays an important role in supplying heat to the polar regions. This conveyor belt operates because of two important properties of water; colder water is denser than warmer water, and saltier water is denser than fresh water. Warm surface water from the Equator travels north into colder regions and cools down. As it does, it gets denser and sinks deep into the ocean.
With a warming globe, more melting icebergs and Arctic sea ice could change this pattern. Melting ice means more fresh water to make the surface water in the ocean less salty and less dense, a process called freshening. If the surface water becomes less dense, it can’t sink, therefore slowing down or disrupting the global ocean conveyor belt. If you stop that circulation, then it could actually lead to a cooling in Western Europe even as the rest of the globe continues to warm up. That’s because right now ocean currents carry warmth from the tropics up to the high latitudes, keeping places like England and other parts of northern Europe milder than other places at the same latitude. Some estimates suggest that if the global ocean conveyor belt were to stop completely, average temperatures in Northern Europe could cool by up to 5–10°C (9–18°F). Even a major slowing of the circulation could have a big impact on regional climate.
There is evidence in the distant past for this kind of freshening and cooling. During the last ice age, there were periods called Heinrich events in which vast numbers of icebergs flowed into the North Atlantic from the Laurentide Ice Sheet, which covered most of present-day Canada. It appears these icebergs helped to freshen the North Atlantic and disrupt the global thermohaline circulation enough to cool the climate of Europe and the North Atlantic, perhaps by more than 2°C (3.8°F).
There are already signs that the Atlantic part of the thermohaline circulation (also called the Atlantic Meridional Overturning Circulation or AMOC) is weakening. In its 2018 report on the impacts of 1.5°C of global warming, the Intergovernmental Panel on Climate Change found that “it is more likely than not that the AMOC has been weakening in recent decades,” as surface waters over the North Atlantic are showing a cooling trend. The panel added that “it is very likely that the AMOC will weaken over the 21st century,” most likely by 11% to 34%. However, the panel also found there is no evidence that the circulation will shut down completely from a global warming of 1.5°C or even 2.0°C.
A study published just last month in the journal Science finds that the AMOC may have weakened and then resurged over relatively short periods (as little as a century) during the last few intervals between ice ages. They noted that “the slowdowns were often accompanied by iceberg-born debris—a sign that meltwater from the Greenland Ice Sheet could have caused this sputtering. The debris suggests Greenland’s fate today not only affects sea level rise; it could also modulate the climate.”
For the Southern Hemisphere, research published in 2019 in the journal Nature Climate Change found that an increase in the number of Antarctic icebergs can weaken and delay the effect of global warming in the Southern Hemisphere. Again, this is a complicated dance. Icebergs can persist for years and are carried by winds and currents through the Southern Ocean until they reach warmer waters and ultimately melt. The melting process cools ocean waters like ice cubes in a cocktail glass. Also, as with northern icebergs, freshwater discharge from icebergs impacts currents by lowering ocean salinity.
The team of researchers, led by Fabian Schloesser (University of Hawaii–Manoa), ran a series of global warming computer simulations, which include the combined freshening and cooling effects of icebergs on the ocean. The size and number of icebergs released in their model mimics the gradual retreat of the Antarctic Ice Sheet over a period of several hundred years. By turning on an off the "iceberg effect" in their climate model, the researchers discovered that icebergs can significantly slow down human-induced warming in the Southern Hemisphere, impacting global winds and rainfall patterns.
Iceberg discharge is such an important part of the global climate system that the Massachusetts Institute of Technology has built a dedicated model—called MITberg—to better understand how iceberg discharge in both the Northern and Southern Hemispheres can affect climate.
Up close with bergs: iceberg tourism
Recently there has been a tremendous upsurge in what is referred to as iceberg tourism. That includes everything from watching icebergs drift by the coastline of Newfoundland to ocean excursions getting people up close and personal to those drifting frozen behemoths.
When it comes to viewing icebergs from the safety and ease of the shore, the northern and eastern coasts of Labrador and Newfoundland are one of the best places in the world. According to Newfoundland’s tourism department, some 500,000 people visited Newfoundland and Labrador in 2018, a number roughly equivalent to the province's total population.
If you manage to brave the cold waters of the waters off Newfoundland for an iceberg tour, you might get to see some of what’s going on in the ecosystem below the water’s surface surrounding the iceberg. According to polar scientists, as an iceberg melts, minerals from land trapped in the ice are also released, causing a small ecosystem to flourish in the iceberg’s vicinity. Fed by nutrients including iron, communities of phytoplankton bloom. In turn, krill, fish, and seabirds arrive to feed on and around the iceberg. Sometimes you can see these phytoplankton blooms in the wake of a travelling iceberg, a big bonus for tourists.
Tourism isn’t the only business opportunity in icebergs. Some companies craft vodka from water derived from icebergs. (Vodka is about 60% water and 40% alcohol). Producers advertise the point that iceberg water is exceptionally pure and was likely kept in its frozen form for as long as 10,000 years or more. Other companies are bottling ”iceberg water.” One such company claims their water has “contains no nitrates or pollutants” and “an ultra-low minerality, making for a light mouthfeel, with a slight bite and sweetness.” Whether or not the locked-up water within an iceberg is that much purer than today’s water may be up for debate, but perhaps those who buy the product just love the whole idea behind the story of the icebergs.
In Canada, you actually need a government-issued license to harvest icebergs, because they are considered a natural resource. However, there are currently no international treaties that govern the harvesting of icebergs.
Harvesting does not come without its risks. Large icebergs can easily roll over without any advance warning. With all of that mass turning into the water, the rollover can produce a mini-tsunami of sorts, which can easily swamp a nearby watercraft. Those who harvest typically go for the growlers, little bergs that pose much less danger but still contain large volumes of water.
It seems the far North Atlantic has become something of a Wild West for iceberg-related tourism and commerce. “Looking over Disko Bay in Ilulissat…it’s easy to understand why many iceberg harvesters aren’t concerned about causing environmental damage or defining legal ownership. I couldn’t even attempt to count the number of icebergs before my eyes,” said Matthew Birkhold in a 2019 article in the Atlantic. However, as he added, “the environmental and legal details will be important if this niche business becomes a full-fledged global industry. In an ocean filled with competing ships, who gets which iceberg?”
For now, if you are looking for a unique vacation in the springtime (if not this spring), a trip to St. John’s, Newfoundland, to view icebergs might by a great opportunity to see some of the grandest and most beautiful floating objects on the face of the earth. You might even have the chance to toast one of those beautiful icebergs with a glass of their own water!
For more on iceberg behavior and iceberg forecasting, see Part I of this post, which appeared on April 14.