Shock discovery: Greenland ice sheet is teeming with microorganisms

In the vast, frozen expanse of Greenland’s glaciers, it has long been assumed that conditions for life are exceedingly harsh, rendering these icy realms as desolate as deserts. Indeed, plants are nonexistent, and only a handful of animal species have been found in these remote regions. 

However, recent research has upended this assumption, revealing a hidden world of microbial life thriving beneath the ice.

A team of scientists from the Department of Environmental Science at Aarhus University, led by Professor Alexandre Anesio, have made the groundbreaking discovery that glaciers are teeming with life. 

The researchers identified an astonishing variety of microorganisms, including bacteria, algae, viruses, and microscopic fungi, which have adapted to the harsh environment. The sheer diversity of these organisms is staggering, with several thousand different species uncovered so far.

“A small puddle of melt-water on a glacier can easily have 4,000 different species living in it. It’s a whole ecosystem that we never knew existed until recently,” said Professor Anesio.

This new insight into the rich biodiversity hidden within Greenland’s glaciers challenges our understanding of life’s resilience and adaptability.

How do microbes live in these conditions?

The existence of life in such inhospitable environments may not be entirely unexpected, given what we have learned about the tenacity of life over the past half-century. 

Researchers have discovered life several kilometers underground, in conditions devoid of sunlight and oxygen, where billions of microorganisms can “eat” minerals in the bedrock to survive. 

Furthermore, in 2007, European scientists managed to send a colony of over 3,000 microscopic water bears (tardigrades) into Earth’s orbit, where an astonishing 68 percent of them survived the vacuum of space and lethal radiation.

In light of these discoveries, the presence of life on glaciers, where sunlight, oxygen, and water are available, may not be as surprising as it initially appears. 

However, until recently, researchers believed that the ice simply could not provide enough nourishment to support life. The recent findings have proven this assumption to be incorrect.

As Professor Anesio explains, there is indeed nourishment for these microorganisms, albeit in incredibly small quantities. 

What is black algae?

One organism, in particular, has caught the attention of researchers: a small black algae that grows on the ice’s surface, causing it to darken. This seemingly innocuous organism has significant implications for global warming, according to the scientists who have been investigating it.

Professor Anesio explains the connection: “When the ice darkens, it becomes more difficult to reflect sunlight. Instead, heat from the sun’s rays is absorbed by the ice, which starts to melt. The more the ice melts, the warmer the temperature on Earth. The algae therefore play an important role in global warming.”

Over the past few years, the black algae have spread across increasingly larger areas of the ice, accelerating the melting process. Professor Anesio has estimated that the algae’s presence increases ice melt by approximately 20 per cent. 

While the algae have been present on the ice long before the onset of human-induced global warming through industrialization, climate change has created more favorable conditions for their growth. As spring arrives earlier in the Arctic due to climate change, the algae have a longer season to grow and spread.

“The algae spread a little more every year. When I travel to Greenland, I now see vast areas where the ice is completely dark because of the algae,” said Anesio.

Searching for an algaecide

In an effort to mitigate the impact of the black algae on global warming, the experts are exploring potential ways to slow down its growth. They are particularly interested in the complex relationships between the different microorganisms found within the glacier ecosystem, which typically exist in a delicate equilibrium. 

“The various microorganisms on the ice affect each other. Some leave nutrition that others live off. Small viral particles attack and consume bacteria. We believe that some of the fungal spores could eat the black algae. This is what we’re looking for,” explained Professor Anesio.

However, he emphasizes that even if a method to curb algae growth is discovered, it will not be a panacea for climate change, but could potentially slow it down. 

The root of the problem lies in the excessive release of greenhouse gases into the atmosphere, and this is where solutions must be focused. Slowing down emissions remains a crucial priority in the fight against climate change.

Black algae has the same pigment as black tea

Algae are ubiquitous, found in seas, lakes, on trees, rocks, and even as tiny spores in the air. Most algae are greenish in color, a result of the chlorophyll molecule that enables them to photosynthesize. 

However, black algae, found on the ice in Greenland, stand apart. According to Professor Anesio, these algae have evolved to produce a black pigment to protect themselves from intense sunlight and radiation.

“Because the algae live on the ice, they’re bombarded with sunlight and radiation. To protect themselves, they produce a lot of black pigment. It’s actually the same pigment as in black tea. The pigment forms a protective layer outside the algae and protects the chlorophyll molecules against the dangerous radiation,” explained Professor Anesio.

The pigment’s absorption of the sun’s rays generates heat, which melts the ice around the algae. This melting process is actually beneficial for the algae, as they require both water and micronutrients from the ice to survive. However, they can only utilize the water in its liquid state.

NASA is watching

While Anesio’s research on black algae provides crucial insights into climate change, it has also attracted the attention of NASA. The space agency believes the study of life in such inhospitable conditions could prove valuable in the search for extraterrestrial life.

“NASA has approached us several times because we‘re working with life that lives in one of the most inhospitable places on Earth,” said Anesio. “If life thrives on and under the ice, there’s a probability that we’ll also find life in the ice on Mars or Jupiter’s and Saturn’s ice moons, for example.”

Prior to the launch of the Perseverance rover to Mars, NASA invited Anesio to a meeting to discuss the potential for Earth microbes to survive on Mars and contaminate samples. The space agency was keen to learn about the limits of life in extreme environments.

NASA’s interest in this research is driven by the search for liquid water on other celestial bodies. While liquid water has not been discovered on other planets in our solar system, there is evidence of subterranean oceans beneath the icy surfaces of Saturn’s moon Enceladus and Jupiter’s moon Europa. As liquid water is essential for life as we know it, understanding the types of life that can thrive on and beneath ice is of great interest to space agencies.

“Like us, they’re very interested in how the microorganisms on the ice function,” said Professor Anesio. “How much nutrition do they need? What type of nutrition? And how does the ecosystem they are part of work? These are questions that we hope to be able to answer in the future.”

This discovery not only upends our understanding of life in extreme environments but also has implications for the study of potential life on other planets, where similar conditions may exist. 

The hidden world of life beneath Greenland’s glaciers serves as a testament to the extraordinary adaptability of life on Earth, and perhaps, beyond.

More about black algae

Black algae, also known as cryoconite, are a unique type of algae found in extreme environments like glaciers and ice sheets. They are characterized by their black or dark brown color, which is due to the production of a protective pigment called melanin. This pigment shields the algae from harmful ultraviolet (UV) radiation and intense sunlight in their icy habitats.

The black pigment produced by these algae also plays a role in their survival strategy. As the pigment absorbs the sun’s rays, it generates heat, causing the surrounding ice to melt. This creates small meltwater pools, known as cryoconite holes, where the black algae can thrive. 

The liquid water in these pools provides the algae with the necessary hydration and micronutrients from the ice for growth and reproduction.

Symbiotic relationships with microorganisms

One fascinating aspect of black algae is their ability to form symbiotic relationships with other microorganisms, such as bacteria and fungi. This creates a miniature ecosystem within the cryoconite holes, where various species of microbes coexist and rely on one another for survival.

While black algae are intriguing from a biological perspective, they also have significant implications for climate change. As they darken the ice surface, the ice loses its ability to reflect sunlight, leading to increased absorption of solar radiation and accelerated melting. This contributes to a positive feedback loop in which more ice melts, exposing more algae, which in turn darkens the ice further and enhances melting.

The study of black algae not only advances our understanding of life’s adaptability in extreme environments but also provides valuable insights into climate change and the potential for extraterrestrial life. 

Researchers like Professor Alexandre Anesio, who study these unique organisms, help to shed light on the complex relationships between microorganisms in these harsh ecosystems and the impacts they have on the larger global environment.

More about the Greenland Ice Sheet

The Greenland Ice Sheet is a vast expanse of ice covering approximately 1.7 million square kilometers (656,000 square miles) in Greenland, the world’s largest island. It is the second-largest ice body on Earth, after the Antarctic Ice Sheet, and contains around 8% of the Earth’s total fresh water supply. The ice sheet is up to 3 kilometers (1.9 miles) thick in some places, with an average thickness of around 2 kilometers (1.2 miles).

The Greenland Ice Sheet is a significant feature in the global climate system for several reasons:

Albedo effect

The ice sheet has a high albedo, meaning it reflects a large percentage of the sunlight that reaches its surface. This reflection helps to moderate global temperatures by reducing the amount of solar radiation absorbed by Earth’s surface.

Sea level rise

The ice sheet holds enough ice to raise global sea levels by approximately 7 meters (23 feet) if it were to melt completely. Melting ice from Greenland is already contributing to rising sea levels, with recent studies estimating its contribution to be about 0.7 millimeters per year.

Thermohaline circulation

The melting of the Greenland Ice Sheet introduces fresh water into the North Atlantic, which can potentially disrupt the thermohaline circulation, a system of ocean currents driven by differences in temperature and salinity. This circulation plays a vital role in redistributing heat around the planet and maintaining Earth’s climate.

Ice dynamics

The ice sheet’s mass balance – the difference between the accumulation of snow and ice and the loss due to melting and calving – has significant implications for global climate. As the ice sheet loses mass, it contributes to sea-level rise and can also affect ocean circulation patterns.

Ecosystems

The Greenland Ice Sheet supports unique ecosystems, including those containing cryoconite, or black algae. These microscopic organisms play a role in the ice sheet’s albedo and melting rate, as previously mentioned.

Climate research

The ice sheet contains valuable climate records in the form of ice cores. By studying the layers of ice, scientists can gain insights into past climate conditions, atmospheric composition, and volcanic activity, among other things.

The Greenland Ice Sheet is an essential component of the Earth’s climate system, and its behavior is of considerable concern to scientists studying climate change. 

With rising global temperatures, the ice sheet has been losing mass at an accelerating rate, posing challenges to ecosystems, coastal communities, and global climate stability.

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