Ice Age History
The world has witnessed multiple ice ages or glacial ages across the eras. During this time, a significant part of the continents remained covered with ice. This large-scale deposition of ice and glaciation across the continents is termed an ice age. This article will discuss what an ice age looks like and when our planet witnessed ice ages in the previous eras.
What is an Ice Age?
The drastic reduction in temperature in the earth’s atmosphere led to the formation of ice and glaciers across the continents. The major part of the continents remained under the ice for millions of years, affecting the flora and fauna of the earth’s ecosystem. Many new species evolved, whereas many got eradicated. The advent of the ice age always marked the development and progress of new species.
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The Prime Characteristics of the Ice Age are:
Formation of heavy layers of ice, covering the major part of the landmass on earth’s crust.
Continental glaciations resulting in the freezing of rivers and freshwater bodies.
Drastic reshaping of the continental shapes due to shrinking of mass and expansion of water.
Ice ages affected the tectonic movements of the continental and oceanic plates resulting in the formation of new landmasses and continents.
Iceseemed to exist for millions of years in prime areas are polar caps, alpine glaciers, and a major portion of the continental landmass.
It is also called glaciations, stadials, etc.
Ice Ages on Earth
Now that we know what is an Ice Age let us find out the different ice ages our earth has witnessed since its formation. As per the archaeologists, the first-ever ice age recorded was during the Precambrian Time. It occurred 570 million years back. The structure of the earth’s crust and other fossilized evidence confirm that this is the first ice age on earth. The most recent ice age happened in the Pleistocene Epoch (ranging from 2.6 million years to 11,700 years).
It is hard to believe, but our earth was majorly covered with ice just several thousand years back. This Ice Age period is significantly important for the evolution of warm-blooded animals such as mammals and humans. The earth has also witnessed smaller ice ages that are not significant when it comes to the span. As per the archeologists and historians, a small ice age progressed but vanished within three centuries. The Little Ice Age commenced in the 16th century and ended in the 19th century. Its development reached its epitome in the 1750s when the glaciers took the biggest shape. It has been found that the glaciers during the 1750s brought a bigger shape than when the latest ice age ended 11,700 years back.
Causes of an Ice Age
1. Atmospheric Changes
When the greenhouse gases in the earth’s atmosphere are reduced considerably, the earth’s surface is unable to hold the heat absorbed from the sunrays. It resulted in a drastic reduction of the temperature below the freezing point.
2. Continental Positions
As per the Ice Age history, the continental positions of the earth’s landmass can block or increase the warm water flow from the equatorial region to the polar caps. On the other hand, reduced absorption of sunrays at the polar region can result in glaciations.
3. Oceanic Current Fluctuations
The position of the continents due to tectonic plate movements resulted in climatic changes and oceanic current fluctuations. The hindrance in exchanging water between Pacific Oceans and the tropical Atlantic caused glaciations in the North American landmass.
4. Tibetan Plateau
It is considered the roof of the world. Due to tectonic movements, the height of this plateau increased, passing the snow line and leading to the formation of ice across the landmass. This is what is considered the prime reason that triggered the Pleistocene Ice Age.
These factors decided the length of an Ice Age period. The last ice age ended 8000 years ago, but its effect can still be seen. Our earth is currently in a Quarternary Glaciation Stage. It is an intermittent stage between a glacial age and a greenhouse period. It is the aftereffect of the Ice Age real life witnessed. The remaining polar ice caps and the glaciers feeding our snow-fed rivers, and the bearable temperature explain the features of this period.
Effects of Glacial Ages
Ice Age all parts that occurred in the earth’s history can only be explained by the evidence gathered by archeologists across the world. The effect of glaciations can also be calculated from the latest glacial age that we survived.
The weight of the ice sheets can change the formation of the earth’s crust resulting in various topographical features. The more minor topographical features apart from drifting of continental mass such as the formation of lakes, rivers, moraines, etc., also resulted from this.
FAQs on Ice Age
1. What exactly defines an Ice Age?
An Ice Age is a long-term period in Earth's history marked by a significant decrease in global temperatures. This sustained cold leads to the expansion of continental and polar ice sheets and alpine glaciers. It is important to know that within a larger Ice Age, there are warmer periods called interglacials (like the one we are in now) and colder periods called glacials when ice advances significantly.
2. What is the difference between an 'Ice Age' and a 'glacial period'?
These terms describe different scales of time. An Ice Age is the entire long-term era of global cooling, which can last for millions of years. A glacial period is a colder phase *within* an Ice Age when glaciers and ice sheets expand dramatically. The warmer phases between glacial periods are known as interglacial periods. We are currently living in an interglacial period of the most recent Ice Age.
3. When was the most recent Ice Age that students learn about in History?
The most recent Ice Age, scientifically known as the Pleistocene Epoch, began about 2.6 million years ago. However, the period most people refer to as "The Ice Age" is the last major glacial period within this epoch. This glacial period reached its peak around 20,000 years ago and concluded about 11,700 years ago, paving the way for modern human civilisation.
4. What causes an Ice Age to begin and end?
The onset and conclusion of an Ice Age are caused by a combination of factors, not a single event. The primary drivers include:
- Milankovitch Cycles: These are predictable, long-term changes in Earth's orbit, tilt, and wobble that alter the amount of solar energy reaching the planet.
- Atmospheric Composition: Reduced levels of greenhouse gases like carbon dioxide (CO2) in the atmosphere lead to global cooling.
- Plate Tectonics: The slow movement of continents can change ocean and wind currents, affecting global heat distribution.
- Volcanic Activity: Major volcanic eruptions can eject ash and aerosols into the atmosphere, blocking sunlight and causing short-term cooling.
5. How do scientists have proof of what the Ice Age was like?
Scientists use various forms of direct and indirect evidence to reconstruct past Ice Age conditions. The key methods include:
- Ice Cores: By drilling deep into glaciers in Antarctica and Greenland, scientists analyse trapped air bubbles that reveal the composition and temperature of ancient atmospheres.
- Ocean Floor Sediments: The chemical makeup of fossilised marine organisms found in sediment cores indicates past ocean temperatures.
- Geological Landforms: Features such as U-shaped valleys, moraines (ridges of rock left by glaciers), and large, out-of-place boulders (glacial erratics) are clear physical evidence of past ice movement.
- Pollen Analysis: Ancient pollen preserved in lake beds helps identify the types of plants that grew, which in turn indicates the climate of that period.
6. What were the major effects of the last Ice Age on the planet?
The last Ice Age had profound and lasting effects on Earth's geography and biology. Key impacts included the formation of massive ice sheets covering large parts of North America and Eurasia, a significant drop in global sea levels by up to 120 metres, and a major shift in climate zones. This reshaped coastlines, carved out new landscapes like the Great Lakes, and forced many species of plants and animals to either migrate, adapt, or become extinct.
7. What kind of animals are famous from the Ice Age?
The last glacial period is known for its incredible megafauna (large animals). Some of the most famous examples that adapted to the cold environment include the woolly mammoth, sabre-toothed cat (Smilodon), giant ground sloth, woolly rhinoceros, and the dire wolf. These animals thrived on the vast, cold, grassy plains known as the mammoth steppe.
8. How did early humans manage to survive the harsh conditions of the Ice Age?
Early humans showcased remarkable ingenuity to survive the Ice Age. Their survival was based on several key adaptations:
- Advanced Toolmaking: They created sophisticated stone, bone, and wood tools for hunting, scraping hides, and other essential tasks.
- Control of Fire: Fire was critical for warmth, cooking food (which increased nutrient absorption), and protection from predators.
- Effective Clothing and Shelter: They crafted tailored clothing from animal hides and furs and used natural shelters like caves or built simple dwellings using materials like mammoth bones.
- Social Cooperation: Hunting large animals like mammoths required organised group effort, fostering strong social bonds and cooperative strategies.
9. Could another glacial period happen in the future?
According to Earth's natural climate patterns, known as Milankovitch cycles, our planet is due to enter another glacial period in the distant future (likely in the next 50,000 years). However, the current high concentration of human-caused greenhouse gases is creating a powerful warming effect. Scientists believe this anthropogenic climate change could significantly delay, alter, or possibly even prevent the next naturally occurring glacial cycle.
