We explain what ice ages are and how they originate. In addition, their characteristics, their effects and the sciences that study them.
What is ice era?
An ice age, glaciation, ice age or glacial age is a geological period in which intense cooling of the cooling of the climate land. The reduction of the planet’s temperature causes the freezing of the waters and the expansion of the ice masses.
Throughout the geological history of the Earth, there have been different ice ages with different durations, but there has always been extensive periods of time. During these glaciations, life had to adapt to a very important descent of temperature throughout the planet. For this reason, in the different ice ages they took place Great species extinctions that failed to adapt to these changes.
The Land has experienced numerous ice ages in a cyclicallythe last of which began 110,000 years ago. The periods of time between ice ages are called interglacial, and are characterized by the increase in temperature and the melting of glaciers and polar caps. It is estimated that Human civilization developed and would be living in an interglacial period started approximately 10,000 years ago.
The Interglacial periods They are characterized by more stable and warm temperatures, with important descents at the level of polar and continental ice. This translates into an increase in hydrosphere levels (oceans, seas, rivers, lakes) and water vapor in the atmosphere.
See also: You were geological
Characteristics of ice ages
The main characteristics of ice eras are the following:
- They were long periods of great cooling of the planet.
- Five eras were identified throughout the geological history of the Earth.
- Life had to adapt to a very cold and dry climate.
- There were great extinctions of species that could not adapt to the cooling of the planet.
- They could have occurred due to changes in the atmosphere, in the terrestrial orbit or an obstruction in the arrival of solar energy.
Causes of Ice Eras
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 produced by a reduction in greenhouse gases in the atmosphere, which would have notoriously decreased the temperature of the planet.
- Solar energy obstruction. An intense volcanic activity could have launched large amounts of ashes to the atmosphere and obstructed the arrival of sunlight to the earth. This would have caused a temperature reduction due to the decrease in solar light and heat.
- Changes in Earth orbit. Variations in the orbit of the earth around the sun, such as changes in distance or inclination, could have influenced the quantity and distribution of solar radiation that reached the planet, which could have caused a global cooling.
- Movement of tectonic plates. Changes in the configuration of the continents due to the movement of tectonic plates could have influenced the weather. The formation of large mountain chains and the distribution of the oceans affected atmospheric and ocean circulation, which in turn would have had an impact on the global climate.
Consequences of ice ages
The different glaciations have had effects of different nature. The main consequences of ice ages can be classified as:
- Geological. The glaciations have generated a particular type of erosion in the geological structures, either because of their cooling, by the pressure of the ice or abrasion masses, which left a very specific evidence in the rocks of those periods.
- Paleontological. The cooling of the planet during the eras of ice produced mass extinctions of plants and animals that could not adapt to the new climatic conditions.
- Marinas. During the glaciations, large amounts of water were stored in the form of ice in the glaciers, which reduced sea level.
History of Ice Eras
Although in the present only 10 % of the earth’s surface is covered by ice, it is known that it was not always the case. Five extensive ice ages have been identified throughout the geological history of the planet:
- Huronian glaciation. It started 2.4 billion years ago and culminated 2.1 billion, in the Paleoproterozoica era.
- Sturtian-Varangian glaciation. It started 850 million years ago and ended 635 million, in the Neoproterozoica era.
- Andean-Saharan glaciation. It started 450 million years ago and ended 420 million, in the Paleozoic era.
- Karoo glaciation. It started 360 million years ago, in the Paleozoic era, and ended 100 million ago, in the Mesozoic era.
- Quaternary glaciation. It started 2.58 million years ago, in the Cenozoic era, and ended approximately 12,000 years ago.
Animals in ice ages
The animals that could withstand the reduction of the planet’s temperature developed biological adaptations that allowed them to survive: thick furs and fatty layers to isolate the interior of their cold bodies, metabolisms adapted to the low temperatures and drought, and hypercaloric diets.
Some of the animal species with these characteristics were:
- The Lanudo Mammut. His body was covered with wool layers up to 1 meter long and possessed adapted teeth to crush the hard bark of frozen vegetation.
- Saber teeth tiger. He was a powerful predator, with 18 centimeters long fangs and a bite that allowed them to open their jaw at 120 degrees, which guaranteed an effective hunt in frozen plains.
- Lanudo rhinoceros. Acts of the current rhino, could weigh up to 4 tons with its massive body and covered with wool. Their horns and skull were stronger and more bulky, to be able to dig in the snow in search of food.
Earth “snowball”
Global glaciation, super glaciation or land “snowball” is a hypothesis regarding what happened in the cryogenic period of the Neoproterozoic era, during which one or more global global glaciations would have occurred, which covered the entire planet with ice and snow the entire planet and lowered its average temperature to -50 ° C.
It is estimated that this phenomenon-muttered in the glaciation of Sturtian-Varangian-lasted about 10 million years, and during this ice age it would have extinguished practically a lifetime on the planet. However, their veracity, duration and magnitude are a matter of debate within the scientific community to this day.
The Würm
Würm’s glaciation, also known as Wisconsin’s glaciation, is the last of the registered ice ages. It started 110,000 years ago and culminated 12,000, with the beginning of the increase in temperatures in the Holocene period.
During the Würm, large land extensions were occupied by glaciers and polar caps increased their extension. This reduced the level of the seas and contributed to the descent of the planet’s temperature, even in tropical and equatorial areas. In addition, during this period the Homo sapiens in Africa and dispersed throughout the world.
Glaciology
Glaciology is the branch of physical geography that studies the current and past phenomena linked to the traffic of water to their solid states: ice, snow, hail or glaciers. This is the science that is responsible for analyzing, together with geology, the marks of the eras past glaciers on the earth’s surface. This allows to reconstruct what environmental and climatic conditions were during ice.
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References
- ABC Science. (2020). Thus the earth became a gigantic “snowball”. https://www.abc.es/ciencia/
- Earle, S. (SF). Glacial periods in the history of the earth. Librettexts https://espanol.libretexts.org/
- Palarq Foundation. (2022). The glaciation that changed the world: Würm glaciation. https://fundacionPalarq.com/
- Tarbuck, E. and Lutgens, F. (2005). Earth Sciences. An introduction to physical geology. Pearson Education.
