Throughout the millions of years since Earth's formation, there have been periods of glaciation, also known as ice ages . These are periods of time marked by climatic changes that cause a global drop in temperature, to the point where most of the Earth's surface freezes. It's important to understand that when discussing climate change, we need a frame of reference to place it within the broader context of our planet.
Do you want to know the processes of glaciation and ice age of our planet? Here we reveal everything.
Characteristics of an ice age
An ice age is defined as a period of time characterized by the permanent presence of extensive ice cover. This ice extends at least at one of the poles. It is known that Earth has spent 90% of its time during the last million years at the coldest 1% of temperatures. These temperatures are the lowest they have been in the last 500 million years. In other words, Earth is trapped in an extremely cold state. This period is known as the Quaternary Ice Age.
The last four ice ages occurred at intervals of 150 million years. Therefore, scientists believe they were caused by changes in Earth's orbit or changes in solar activity. Other scientists prefer a terrestrial explanation. For example, they attribute the onset of glaciation to the distribution of continents or the concentration of greenhouse gases.
According to the definition of glaciation, it is a period characterized by the existence of ice caps at the poles. By that rule of thumb, right now we are submerged in an ice age, since the polar caps occupy almost 10% of the entire earth's surface.
Glaciation is understood as a period of ice ages in which the temperature is very low globally. The ice caps, as a consequence, extend towards lower latitudes and dominate the continents. Ice caps have been found in latitudes of the equator. The last ice age took place about 11 thousand years ago.
Known ice ages
There is a branch of science that is responsible for studying glaciers. It's about glaciology. It is the one in charge of studying all the natural manifestations of water in solid state. With solid water they refer to glaciers, snow, hail, sleet, ice and other formations.
Each glacial period is divided into two phases: glacial and interglacial. Glacial periods are characterized by extreme environmental conditions and frost across almost the entire planet. Interglacial periods, on the other hand, are more temperate, as they are today.
To date, five glacial periods have been identified and verified: Quaternary, Karoo, Andean-Saharan, Cryogenian, and Huronian . All of these have occurred since the Earth's formation.
Ice ages are characterized not only by sudden drops in temperature, but also by rapid rises.
The Quaternary period began 2,58 million years ago and lasts until the present day. The Karoo, also known as the Permo-Carboniferous period, was one of the longest, lasting approximately 100 million years, between 360 and 260 million years ago.
On the other hand, the Andean-Saharan glacial period has lasted only 30 million years and took place between 450 and 430 years ago. The most extreme period that has taken place on our planet is undoubtedly the cryogenic. It is the most severe ice age in the entire geological history of the planet. At this stage it is estimated that the ice sheet that covered the continents reached the geographical equator.
The Huronian glaciation began 2400 billion years ago and ended approximately 2100 years ago.
The last ice age
We are currently in an interglacial period within the Quaternary glaciation. The area that the polar caps occupies reaches 10% of the entire earth's surface. The evidence tells us that within this quaternary period, there have been several ice ages.
When people refer to "The Ice Age," they mean the last glacial period of the Quaternary period. The Quaternary began 21000 years ago and ended about 11500 years ago. It occurred simultaneously in both hemispheres. The greatest ice extents were reached in the Northern Hemisphere. In Europe, the ice advanced, covering all of Great Britain, Germany, and Poland. All of North America was eventually buried under ice.
After the freeze, the sea level dropped 120 meters. Large expanses of the sea today were on land for that era. This data is quite relevant when studying the genetic evolution of many populations of animals and plants. During their movement across land surfaces in the ice age, they were able to exchange genes and migrate to other continents.
Thanks to the drop in sea level, it became possible to travel on foot from Siberia to Alaska. The vast ice sheets reached thicknesses of 3.500 to 4.000 meters, covering a third of the Earth's landmass. This is very similar to the behavior of glaciers in the Arctic Ocean.
Today, it has been calculated that if the remaining glaciers melted, the sea level would rise between 60 and 70 meters.
Causes of glaciation
The advance and retreat of ice are related to the cooling of the Earth. This is due to changes in the composition of the atmosphere and changes in the Earth's orbit around the Sun. It can also be due to changes in the Sun's orbit within our galaxy, the Milky Way.
Those who think that glaciations are caused by internal causes of the Earth believe that they are due to the dynamics of tectonic plates and their effect on the relative situation and the amount of oceanic and terrestrial crust on the Earth's surface. Some believe that they are due to changes in solar activity or the dynamics of the Earth-Moon orbit.
Finally, there are theories that link the impact of meteorites or large volcanic eruptions with glaciation, as well as the effects they could have on the climate that could be reflected in the impact of an asteroid that affects the Earth.
The causes have always generated controversy and scientists say that we are close to ending this interglacial period. Do you think there will be a new ice age soon?
