We explain what ice ages are and how they originate. Also, their characteristics, their effects and the sciences that study them.
During ice ages, life had to adapt to a very cold climate.
What is the ice age?
An ice age, glaciation, ice age or glacial age is a geological period in which intense cooling of the climate landThe reduction in the planet’s temperature causes the freezing of water and the expansion of ice masses.
Throughout the Earth’s geological history, different ice ages have occurred with different durations, but they have always been long periods of time. During these ice ages, life had to adapt to a very significant drop in temperature across the planet. For this reason, in the different ice ages there were major species extinctions who were unable to adapt to these changes.
The Land has experienced numerous ice ages in a cyclical manner, the last of which began 110,000 years ago. The time periods between ice ages are called interglacials, and are characterized by rising temperatures and melting glaciers and ice caps. It is estimated that Human civilization developed and would be living in an interglacial period that began approximately 10,000 years ago..
The interglacial periods They are characterized by more stable and warm temperatures, with significant decreases in the level of polar and continental ice. This results in an increase in the levels of the hydrosphere (oceans, seas, rivers, lakes) and water vapor in the atmosphere.
See also: Geological eras
Characteristics of ice ages
The main characteristics of ice ages are as follows:
- They were long periods of great cooling of the planet.
- Five ice ages have been identified throughout the geological history of the Earth.
- Life had to adapt to a very cold and dry climate.
- There were major extinctions of species that were unable to adapt to the cooling of the planet.
- They could have been caused by changes in the atmosphere, in the Earth’s orbit or by an obstruction to the arrival of solar energy.
Causes of ice ages
The causes of glaciations can be diverse and are subject to debate. Some of the most accepted theories are:
- Changes in the composition of the atmosphere. Variations in the composition of the atmosphere, particularly in the concentration of greenhouse gases, can influence the climate. For this reason, it is believed that ice ages could have been caused by a reduction in greenhouse gases in the atmosphere, which would have significantly reduced the planet’s temperature.
- Obstruction of solar energy. Intense volcanic activity could have released large amounts of ash into the atmosphere and blocked the reach of sunlight to Earth. This would have caused a reduction in temperature due to the decrease in sunlight and heat.
- Changes in Earth’s orbit. Variations in the Earth’s orbit around the Sun, such as changes in distance or inclination, could have influenced the amount and distribution of solar radiation reaching the planet, which could have caused global cooling.
- Movement of tectonic plates. Changes in the configuration of the continents due to the movement of tectonic plates could have influenced the climate. The formation of large mountain ranges and the distribution of oceans affected atmospheric and oceanic circulation, which in turn would have had an impact on global climate.
Consequences of ice ages
The glaciations have generated a particular type of erosion in the rocks.
The various glaciations have had effects of different nature. The main consequences of ice ages can be classified as:
- Geological. Glaciations have generated a particular type of erosion in geological structures, either due to cooling, the pressure of ice masses or abrasion, which left very specific evidence in the rocks of those periods.
- Paleontological. The cooling of the planet during the ice ages produced mass extinctions of plants and animals that could not adapt to the new climatic conditions.
- Marines. During the ice ages, large amounts of water were stored as ice in glaciers, which lowered sea levels.
History of Ice Ages
The Quaternary glaciation occurred in the Neogene period of the Cenozoic era.
Although only 10% of the Earth’s surface is currently covered by ice, it is known that this was not always the case. Five extensive ice ages have been identified throughout the geological history of the planet:
- Huronian GlaciationIt began 2.4 billion years ago and culminated 2.1 billion years ago, in the Paleoproterozoic era.
- Sturtian-Varangian glaciationIt began 850 million years ago and ended 635 million years ago, in the Neoproterozoic era.
- Andean-Saharan glaciationIt began 450 million years ago and ended 420 million years ago, in the Paleozoic era.
- Karoo Glaciation. It began 360 million years ago, in the Paleozoic era, and ended 100 million years ago, in the Mesozoic era.
- Quaternary GlaciationIt began 2.58 million years ago, in the Cenozoic era, and ended approximately 12,000 years ago.
Animals in the ice ages
The woolly rhinoceros could dig in the snow in search of food.
Animals that were able to withstand the reduction in the planet’s temperature developed biological adaptations that allowed them to survive: thick fur and layers of fat to insulate the interior of their bodies from the cold, metabolisms adapted to low temperatures and drought, and high-calorie diets.
Some of the animal species with these characteristics were:
- The woolly mammothIts body was covered with layers of wool up to 1 metre long and it had teeth adapted to crush the hard bark of frozen vegetation.
- Saber-toothed tigerIt was a powerful predator, with 18-centimetre-long fangs and a bite that allowed it to open its jaws to 120 degrees, ensuring effective hunting on the frozen plains.
- woolly rhinoceros. Ancestor of the current rhinoceros, it could weigh up to 4 tons with its massive, wool-covered body. Their horns and skull were stronger and more voluminous, so they could dig through the snow in search of food.
Snowball Land
Global glaciation, super glaciation or “Snowball” Earth is a hypothesis regarding what happened in the cryogenic period of the Neoproterozoic era, during which one or several glaciations on a global scale would have occurred, which covered the earth with ice and snow. entire planet and lowered its average temperature to -50 °C.
It is estimated that this phenomenon – framed in the Sturtian-Varangian Glaciation – lasted about 10 million years, and during this ice age practically all life on the planet would have been extinct. However, its veracity, duration and magnitude are a matter of debate within the scientific community to this day.
The Wurm
During the Würm, the Homo sapiens and spread throughout the world.
The Würm Glaciation, also known as the Wisconsin Glaciation, is the last of the recorded ice ages. It began 110,000 years ago and ended 12,000 years ago, with the beginning of the increase in temperatures in the Holocene period.
During the Würm, large areas of land were occupied by glaciers and the polar caps increased in size. This reduced sea levels and contributed to a drop in the planet’s temperature, even in tropical and equatorial areas. Furthermore, during this period there emerged Homo sapiens in Africa and spread throughout the world.
Glaciology
Glaciology studies the marks of past ice ages.
Glaciology is the branch of physical geography that studies current and past phenomena related to the transition of water into its solid state: ice, snow, hail or glaciers. It is the science that is responsible for analyzing, together with geology, the marks of past ice ages on the Earth’s surface. This allows us to reconstruct what the environmental and climatic conditions were like during ice ages.
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References
- ABC Science. (2020). This is how the Earth became a gigantic “snowball”. https://www.abc.es/ciencia/
- Earle, S. (n.d.). Ice Ages in Earth’s History. LibreTexts. https://espanol.libretexts.org/
- Palarq Foundation. (2022). The glaciation that changed the world: the Würm Glaciation. https://fundacionpalarq.com/
- Tarbuck, E. and Lutgens, F. (2005). Earth sciences. An Introduction to Physical Geology. Pearson Education.