How are glaciers formed? From a snowflake to an ice giant

Glaciers are some of nature’s most powerful creations. These huge masses of ice not only shape landscapes, but also play a key role in regulating our planet’s climate. How are they formed? What features do they have? And why is their presence so important for Earth’s future? Let’s take a closer look at this ice mystery.

How are glaciers formed?

Glaciers are born in places where snow accumulates over many years, and summer melting cannot keep up with winter precipitation. Special climatic conditions – low temperatures, high humidity and regular snowfall – play a key role. The process begins with the gentle settling of successive layers of snow, which become more and more compact over time. In this icy metamorphosis, air is gradually squeezed out of the bubbles between them.

Initially, firn is formed – compact, granular snow, a kind of bridge between fresh precipitation and hard glacial ice. The transformation of firn into glacial ice takes decades, sometimes even hundreds of years. This hard, almost transparent ice is the result of relentless weight and the passage of time. When a glacier reaches a critical mass, it begins to move under the influence of its own weight. Although this movement is almost imperceptible to the human eye, it is of great importance in shaping the landscape. Moving masses model their surroundings in a way that leaves a lasting mark on the surface – they not only destroy, but also create new landscape forms.

Glaciers up close

The movement of a glacier can be compared to a slow but relentless stream. The upper layer moves faster, while the lower, plastic part slides over the rocky ground. As a result of this process, the huge and heavy mass sculpts the rocks, creating monumental valleys, steep walls and picturesque lakes.

There is no shortage of examples of glacial formations. In the Yosemite Valley in the United States, we can admire spectacular landscapes, shaped by a long disappeared glacier. In Europe, such traces can be seen in the Alps, where lakes, such as those of Geneva and Bodensee, owe their formation to retreating ice masses. Norwegian fjords, such as Sognefjord or Geirangerfjord, on the other hand, are the results of centuries of glacial relief, which created deep valleys filled with water.

Each of these landscapes is a unique reminder of the icy past. Glacial sculpture combines the power of destruction with creation – destroying existing forms and creating new ones.

The magic of blue ice

One of the most unusual phenomena associated with glaciers is their color. Glaciers often have an intense blue hue that gives them an almost magical character. Where does this color come from? The answer lies in physics. Glacier ice absorbs long wavelengths of light (red and orange), reflecting shorter wavelengths – blue.

Glaciers are not uniform in composition or structure. Inside them you can find tunnels, underground rivers and even trapped fragments of rock or sediment. All this makes them not only unique natural formations, but also fascinating laboratories of nature.

Diversity of glaciers

Glaciers come in many forms, and their diversity reflects the conditions under which they form:

• Mountain glaciers are smaller formations found in the Himalayas, Andes or Alps. They are crucial to local ecosystems, and have the important task of supplying water to millions of people.
• Continental glaciers, such as those covering Greenland and Antarctica, are true giants that contain the world’s largest freshwater resources. Their melting affects global ocean levels.
• Shelf glaciers float in ocean waters, and icebergs that break away from them become a habitat for many marine organisms, while also posing a threat to shipping.

Glaciers a reflection of global change

We can’t say about glaciers that they are just masses of ice. On the contrary, they are real treasure troves of knowledge about our planet. Their layers act as natural archives – they store information about past climatic conditions, volcanic eruptions and even atmospheric pollution. Each of their layers is like a page from the book of Earth’s history, going back hundreds of thousands of years. For scientists, they are an invaluable source of knowledge that allows them to track the changes that have taken place on our planet over the centuries.

When glaciers disappear, they leave behind a void – literally and figuratively. Their melting contributes to rising ocean levels, threatening not only coastal communities, but also fragile aquatic ecosystems. But that’s not all – glaciers are a record of our planet’s history, allowing scientists to better understand climate change.

For example, ice cores extracted from the depths of glaciers contain a record of the composition of the atmosphere hundreds of thousands of years ago. Analysis of this data allows us to track changes in the levels of greenhouse gases, such as carbon dioxide and methane, as well as temperatures [1]. This allows us to predict future risks and better prepare for the challenges of global warming.

Glaciers are not just scenic wonders – they are the foundations of the global ecosystem. They are a key source of drinking water, regulate the hydrological cycle and support unique ecosystems. Their disappearance is a problem that affects not only polar or mountain regions, but the entire world.

[1] DOI: 10.1126/science.adk3705