Introduction to glaciers
There are thousands of glaciers on our planet, but not everyone has the privilege of witnessing one up close. If you’ve never seen one, you’ve likely heard about them as a powerful illustration of the effects of global warming on our planet.
Southern Patagonian Ice from space ©NASA
Survivors of the last ice age
Because they are extremely vulnerable to climate change, several glaciers have disappeared in recent decades, and almost all have reduced their volume due to the accelerated increase in temperature at all latitudes during the last century. The ecological value of glaciers is not well known by everyone: their ice constitutes almost 90% of the freshwater available in the world, and taking into account that drinking water is an increasingly scarce natural resource, glaciers are essential for the future of all. The importance of glaciers on Earth is directly proportional to the importance of glaciations.
Ice ages are cyclical climatic events that extend over thousands of years, in which prevailing conditions of low temperature and humidity produce a marked increase in the size of the total ice mass on the planet - during the last ice age, ice covered almost a quarter of the land. Each ice age is preceded by a period of milder climate, with the consequent reduction of the ice caps.
Today we know that the most important moment of the last great ice age occurred only 18,000 years ago – a short period of time in geological terms – and places us in the present as recent spectators of its effects on the Earth.
Glacial ice accounts for almost 90% of the world’s available freshwater
Hundreds of glaciers are disappearing due to the accelerated increase in global temperature
Glaciers form in places where snow can stay in one place all year round.
From where they originate, their movement is due to the action of gravity, as if they were rivers of ice
How are glaciers formed?
Glacier formation starts in regions where snow can persist year-round due to the absence of sufficient warmth to cause complete melting. These areas, known as feeding zones, accumulate snow year after year, which is gradually compressed by its own weight. As a result, the trapped air between the snow crystals is released, leading to the formation of progressively larger and more compact granules.
As these corpuscles lose the air between their particles, they continue to fuse. Consequently, the pristine whiteness and luminous appearance of snow are left behind to give way to an increasingly opaque and dense mass known as sleet – the transitional state between snow and ice.
As the tiny air particles trapped within the snow are forced out by compression, the snow gradually becomes translucent and solid, transforming into a gel-like state called spongy ice. The final stage of this compaction process is glacial ice, distinguished by its distinctive blue color. The older the ice, the lesser the amount of air it contains, resulting in a more vibrant blue hue.
Glaciers, appearing stationary, are actually in constant, albeit imperceptible, movement. Originating from high elevations, their movement is solely due to gravity. Like rivers of ice, glaciers follow their natural course, determined by the terrain’s slope and their mass. Like other waterways, glaciers often reach their end in lakes, lagoons, or the sea.
Unstoppable
Imagine how much greater the transformative energy of water is when it’s in a solid state, given its powerful erosive action in a liquid state, capable of creating the geographical features we see on coastlines and river deltas. Glaciers, along with volcanic activity and the movement of continental plates, were the primary forces responsible for shaping the landscapes of southern Patagonia, acting like bulldozers that obliterated everything in their path.
After their retreat, the glaciers left behind huge swaths of land that were squished under the weight of thousands of tons of ice. These areas became huge U-shaped valleys and vast plains. The glaciers also carved out countless canals and fjords, and filled the deep depressions and channels they had dug into the ground, creating massive lakes. The glaciers had a huge impact on the region’s geography, and even though the glaciers are much smaller now than they were during the big glaciations of the past, their power is still felt today