Throughout the millions of years that have passed since the earth’s formation, there have been times of the Ice Age. The ice age is a period when climatic changes occur that lower global temperatures. They do it in such a way that most of the earth’s surface freezes.
But why was the era termed Ice Age? Was it because all the oceans and sea waters were frozen and turned to ice, or was it because the thick ice sheets covered the whole earth’s surface?
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Reason for the terminology
The period when most parts of the planet, if not whole, were covered with ice sheets is termed Ice Age, and it is still called so. The following reasons clarify why the term ice age is relevant to the period.
1. Ice age Terminology proposed in 1837
As early as the 18th century, the Swiss naturalist Pierre Martel noted that the inhabitants of the Chamonix Valley (in southeastern France) attributed the presence of immense erratic blocks to the fact that the glaciers had been much larger.
Several researchers in the following century also supported this idea. Among them was the Swiss engineer Ignaz Venetz, who in 1829 presented a detailed paper on the existence of glacial preterites to the Swiss Academy of Natural Sciences.
But the scientific world viewed his thesis with skepticism. Most scientists and researchers at the time believed that the earth had gradually cooled from an initial molten state.
Venetz was not the only naturalist to challenge preconceptions and try to convince the scientific community that our planet had a much harsher climate. His compatriot Louis Agassiz took over. The young geologist and paleontologist learned of Venetz’s groundbreaking theory thanks to botanist Karl Friedrich Schimper, a friend from college days.
In 1837, Schimper proposed the term Ice Age to refer to that time of intense cold. Shortly after that year, Agassiz christened it glaciation and presented his thesis at the Swiss Academy of Natural Sciences. His proposal, however, had the same icy reception as Venetz’s. Persevering, he then embarked on an ambitious program of observing mountain glaciers.
His work culminated in the publication of Studies on Glaciers (1840). Agassiz and his followers showed that the great masses of ice that constituted the glaciers left an unequivocal pattern on the landscape’s topography. Thanks to him, they could deduce that there were glaciers with an extension of hundreds of kilometers in other times, which the warm climate had shortened.
2. Ice Age as described today
The ice age corresponds to a period when the temperatures of the entire planet dropped and remained so for a long time.
It is associated with a very long period in which temperatures are extremely low, allowing continental areas to freeze and expand; as rivers and seas freeze, glaciers on top of mountains increase. As a result, the expansion of continental and polar ice sheets and icy mountains occurred.
The oldest ice age occurred in the Precambrian period, about 570 million years ago. The most recent happened in the Pleistocene period. Ice Age usually refers to the Pleistocene ice age, which began around 1.7 million years ago and ended approximately 20,000 years ago.
3. Features of Ice Age
Scientists across the globe have been studying fossils, elements, present-day glaciers, and ice sheets near ancient volcanic eruptions to detail the ice age, its origin, and its causes.
Earth has undergone at least five primary ice ages, and all of these ice ages had some standard features, which were:
- Ice ages could last millions to tens of millions of years.
- Glaciers covered large areas of the earth, including regions that were currently ice-free and had a temperate or relatively warm climate.
- The ice caps were located in both hemispheres, northern and southern.
- Global temperatures were very low.
- Due to the advance of ice and the freezing of water, they formed solid bridges between some areas previously separated by a body of water.
4. Earth was like a snowball
Hundreds of thousands of years ago, the planet was completely covered with ice, which gave it the appearance of a giant snowball, according to the hypothesis of global glaciation.
At that time, the climatic conditions were “so severe, that the Earth’s entire surface, from pole to pole, including the oceans, froze completely,” says Melissa Hage, an environmental scientist at Oxford College at Emory University.
Scientists believe that the earth went through three or four ice ages (each about 10 million years ago), between 750 million and 580 million years ago, when ice covered almost all or the entire surface of our planet. Specialists estimate that the global temperature dropped to 50 degrees below zero during these periods.
5. Evidence from Research
Many do not believe that it is possible to prove the presence of ice in someplace if it has already melted, especially if it melted tens of thousands of years ago. Those who do not believe are wrong because the ice cover leaves behind evident traces in the form of diamicton.
These and other deposits are created by glacial lakes and glaciers, which can either grow in different directions or slide into the sea. These glaciers break into ice which is lighter than water floats. As it swims, it gradually melts and sheds the collected rock. From these dumps, one can understand where this ice was and how it ended up in a new place.
Those rocks that did not enter the ocean, but moved over land, can also help study the ice age. Also, sediments at the bottom of mountain lakes, many of which were formed during the Ice Age, can help research.
6. Extremely Low Temperature
The last epoch of glaciation began about 100,000 years ago and ended about 25,000 years ago. At this time, the ice cover area was constantly changing either up or down but reached its peak in the period of 27-19 thousand years ago.
During this period, the most challenging conditions on earth were mainly in the region of present-day France and Germany. The average planet temperature was 6 degrees Celsius lower than now. The world ocean level was lower by 135-150 meters, and the thickness of the ice cover on land reached 3-4 kilometers.
The humidity on the planet was also very low. It led to deforestation and even desertification of southern Australia. A study led by the Arizona University, USA, estimated that the earth’s average temperature during the Last Glacial Period was 7.8 ºC.
7. Ice sheets formed far beyond the poles
US researchers published a study that presented robust evidence about the origin of the ice ages. They investigated the three significant glacial periods that have occurred on earth over the past 540 million years.
These are times when global temperatures plummet and, as a result, large ice caps and glaciers appear far beyond the poles. Scientists found that such icy times trigger comes from the planet’s warmest zones when a specific geological phenomenon occurs in tropical areas.
8. Topography changes, and Lake Formation
Experts gained knowledge of ice ages from studying fossils, landforms, ice cores, and deep-sea sediments they have found in the ground. Ice has effects on the earth’s surface.
One of the most obvious is the formation of geographical accidents because it carves the earth’s surface as it passes through the surface. Fjords, moraines, erratic blocks, and cirques are typical in regions of the northern hemisphere where evidence of ice remains.
Many lakes are also the result of glaciations; once a basin is carved and the ice melts, water is deposited over the depression. The Great Lakes found in the United States and Canada formed about 14,000 years ago when the ice age ended.
9. Animals existing during ice age
The animals that survive the changes of the ice ages and that, in addition, adapt to life in the frozen wastelands usually have particular characteristics: thick fur and layers of fat to insulate the interior of their bodies from the cold, metabolisms adapted to cold and drought, and hypercaloric diets.
However, we can understand the specific way in which each species dealt with the cold by looking at the main animal species of the last ice age, such as:
The woolly mammoth
Mammoths adapted to the cold; layers of fur up to 1 meter long covered their bodies, and they had teeth adapted to crush the hard crusts of frozen vegetation. They lived up to 80 years.
With a body shorter, heavier, and thicker than a lion, these powerful predators had tusks 20 cm long and a bite that allowed them to open their jaws to 120°, guaranteeing an effective hunt on the frozen plains of the time.
The ancestor of today’s rhinos could weigh up to 4 tons with their massive, wool-covered body. Their horns and skull were stronger and bulkier, so they could dig in the snow searching for food.
10. Ice covered planet every 100000 years
A team of researchers from the British University of Cardiff explains why our planet suffers cyclically and, every 100,000 years, intense ice ages. It is known as “the 100,000-year problem“, and it is a mysterious phenomenon that has been occurring for at least the last million years of earth’s history.
During these recurrent cold periods, vast ice sheets cover the entirety of North America, Europe, and Asia. The blame for that change could lie with the oceans or, more precisely, how the oceans absorb carbon dioxide from the atmosphere.
By studying the chemical composition of tiny fossils dug up from the ocean floors, the researchers found an increased amount of CO2 stored in the deep ocean during Ice Age periods at regular 100,000-year intervals.
And that suggests that at the time, extra carbon dioxide was leaking from the atmosphere into the sea, lowering the earth’s temperature and allowing vast ice sheets to engulf the entire northern hemisphere of the planet.
11. Geological structure at the time of the Ice Age
Ice ages have had a significant effect on our planet. Of course, they did not displace the continents and did not change the coastline, but given their constant implications, it was pretty significant.
Because of this phenomenon, the glaciers gradually broke away from the mountains, which caused significant wear on the rocks as they carried the clay for many kilometers. Eventually, a massive area of northern Europe was covered by a thick layer of ice.
The territories now Canada, the north of the USA, Germany, Great Britain, Poland, Belarus, and most of Russia were covered with a thick layer of ice sheets.
There were also areas closer to the equator covered with ice—for example, the rocky mountains in North America. The sea level dropped a hundred and twenty meters from what it is today so that the people could cross the English Channel on foot.
A 3-km-thick ice cap formed over the Scandinavian peninsula and another 1.5-2 km thick over Ireland and Great Britain. Huge icebergs reached Lisbon, and in the Iberian Peninsula, the average annual temperature was between ten and twelve degrees colder than today.
Ice sheets covered much of northern Europe, from Scandinavia to central Germany. A periglacial landscape extended to the south of the icy front, one whose ground is permanently frozen, up to many meters deep.
This soil known as permafrost persists today in large areas of Siberia and Alaska, more than three hundred meters deep. In the permafrost of 20,000 years ago, the trees could not sink their roots, so only the tundra (covered with lichens, mosses, and grasses) had a place.
In summer, when the daytime temperature could slightly exceed 0 °C, the surface layer of the soil thawed, and large ponds and swampy areas opened up in it. But not all were desolate landscapes. To the south of the tundras, a part of the continent was covered by coniferous forests. The Mediterranean areas were deciduous forests (with beeches, oaks, and holm oaks, among other species).
There were not so many ice sheets in the planet’s southern hemisphere. It is because the area of the continents is smaller there. However, the Andes were covered in ice. A thick layer of ice didn’t completely cover the poles’ oceans. It was more than now, but the difference was less significant than many people think.
In addition, the ice amount in the ocean depended on the season. There were large areas free of ice in the summer months, even in the Arctic Ocean.
In short, the ice age is termed the ice age because ice covered most of the entire earth’s surface in different epochs. Life was harsh due to extremely low temperatures; species had to adapt and struggle to survive and evolve.
If we suddenly face an ice age, despite all our technology and the ability to build great houses, it will be challenging to survive. It will be possible to live in warmer areas, but the increasing population will make it challenging.
(Last Updated on June 1, 2022 by Sadrish Dabadi)