In the remote reaches of Greenland, the sparkling white ice sheet stretches as far as the eye can see. But over in the far west of the massive island, a mysterious dark patch creates an ominous smear across the landscape. Worse still, it’s growing darker. So what does this mean for the future of the human race?
At both poles of the Earth, vast masses of frozen water known as ice sheets cover the barren land. According to experts, they are formed when snow remains in one spot for an extended period of time. Gradually, more snow lands on top, slowly compacting each layer and transforming it into ice.
Apparently, the term ice sheet applies to any of these masses that reach over 19,000 square miles in size. And at the moment, there are only three in the world. While two of them are located in Antarctica, the smallest of the three, the Greenland ice sheet, covers a huge chunk of Greenland in the Northern Hemisphere.
Because of their vast size, these ice sheets have an important role to play in the complex ecosystem of planet Earth. In fact, they can affect everything from storms to the wind. Furthermore, they are particularly relevant to what’s known as albedo. Specifically, this means the amount of light that any surface reflects away from the earth.
Both water and land have low albedo, so they absorb most of the sun’s energy as soon as it arrives on our planet. But snow and ice have a high albedo, sending light back out into the atmosphere. So, ice sheets are important for keeping our planet cool – but what happens if they starts to melt?
Worryingly, melting ice sheets could exacerbate the effects of global warming by reducing the planet’s high albedo surfaces and replacing them with low ones. And that’s not all. It’s estimated that the complete thawing of these frozen masses could cause sea levels to rise by more than 220 feet around the world.
So, how concerned should we be? Soberingly, there are a number of factors threatening the ice sheets’ continued existence. Chief among them is climate change, and as global temperatures rise, the frozen masses will melt at an increased rate. Moreover, warmer oceans could cause even more destabilization.
However, there is an altogether stranger threat facing the ice sheet that stretches for more than 650,000 square miles across some 80% of Greenland. At over a mile thick on average, it’s a formidable mass that holds a staggering 8% of all the freshwater in the world. But over the years, the sheet has been steadily decreasing in size. In fact, it’s now become the biggest contributor of its kind to rising sea levels across the globe.
For the most part, the Greenland ice sheet is a dazzling, frozen landscape of pure, unblemished white. But scientists poring over satellite images have observed a strange phenomenon over on its western side: a patch of darker ice that forms an alarming strip across the sheet during the summer months.
And worryingly, the patch appears to be getting darker. Known as the “Dark Zone,” this anomaly measures some 250 miles across and stretches for around 60 miles from the edge of the sheet. In the past, some scientists have speculated that the effect might be caused by reflective water sitting on top of the ice.
However, a team of scientists from around the world has recently put forward a different hypothesis. In August 2014 they began surveying the Dark Zone using drones equipped with cameras. These then captured high-resolution photographs of their surroundings.
Moreover, because these images revealed more detail than the satellite imagery that had previously been studied, the team were able to take a closer look at this mysterious patch of ice. And when combined with data collected by specialists on the ground, it allowed them to build up a more complete picture of the region.
On March 14, 2018, the scientific journal Nature Communications published the results of this innovative study. Apparently, researchers had concluded that impurities and algae – not surface water – were responsible for the Dark Zone. But how did they get there in the first place, and why are they clustered in one location?
According to the study, impurities such as dust and black carbon from distant forest fires can end up trapped in the Greenland ice. And once there, they increase the albedo of the surface, thus creating a fertile breeding ground for algae. Then, in turn, these organisms make their own contribution to the Dark Zone.
“Because algae are dark in color they reinforce the Dark Zone,” Professor Alun Hubbard, one of the study’s co-authors, explained. “Thereby you get a positive feedback effect where the ice sheet absorbs even more solar radiation producing yet more melt.” But if this part of the ice sheet is locked in a destructive spiral, what does that mean for our fragile climate?
Certainly, experts seem to be in little doubt that Greenland’s ice sheet is disappearing. In fact, it has shrunk by some 235 billion tons between 2002 and 2011 – compared to just 37 billion tons during the previous decade. And with the Dark Zone apparently set to get even darker, it can only contribute to this worrying trend.
So far, experts estimate that the melting Greenland ice sheet has already caused sea levels to rise by around a third of an inch over 20 years. Furthermore, once past a certain point, the process could self-amplify, causing the entire mass to completely disappear. This would result in catastrophic flooding across the world.
However, some experts believe that it isn’t too late to save the Arctic ice. In 2016 a team of researchers from Germany’s Max Planck Institute for Meteorology released a paper arguing that carbon dioxide emissions were having a direct effect on diminishing sea ice levels. Moreover, they claimed that reducing the amount of greenhouse gases released into the atmosphere would soon stabilize these regions.
But what of the Dark Zone and its slow spread through the ice? According to those involved in the study, further research is required to build a clearer picture of the region and how it impacts on the ice sheet as a whole. Until that time, it remains a sinister shadow across the Arctic, reminding us of just how precarious our world can be.