Glaciations

Climate change is calling into question many scientific discoveries about the glaciationsIn 2004, we had a rather cold winter, with little rainfall and widespread forest fires around the world. These events sparked a debate within science about atmospheric cycles and the potential risks associated with climate change. Some argue that global warming is not caused by humans, but rather corresponds to one of the occasional glaciation cycles our planet experiences from time to time.

In this article we are going to tell you everything you need to know about glaciations and their relationship with climate change.

Oscillations in temperatures

It is known that during the last century the planet's climate has experienced an increase in its average temperatures. This is due to the increase the concentration of carbon dioxide and other greenhouse gases with the capacity to retain heat in the atmosphere. The problem is that some people say our planet has cycles of glaciations. It's true that throughout our planet's evolution, there have been cycles of glaciations and interglacial periods. However, the problem begins when we consider the speed of these glaciations and the global warming prior to them as a variable.

As can be seen in a chronology of glaciations, which we will see later, the time that passes between one glaciation and another is long enough for all animal and plant species and the morphology of ecosystems to adapt to changes in the environment. In this case, we are talking about an increase in global average temperatures in too short a period. Such a short period of time leaves species with no time to adapt, and their populations begin to decline. Population declines are so severe that many have become extinct. If you're interested in learning more about the effects of climate change, I recommend reading about how we've lost control of climate change.

To dispel all doubts, we will present some certainties about the past and the scientific findings. These findings bring into play all the natural mechanisms that seem to influence the evolution of the planet's climate. It must be taken into account that, independently of the influence of human activity, scientists admit that the main natural causes of climate fluctuations are the major glaciations with the wobble of the Earth's axis of rotation. Added to this are changes in the Earth's orbit around the Sun. This is because the entire set of movements modifies the distribution of energy our planet receives from the sun.

Ice ages and changes in Earth's orbit

To understand glacial and interglacial periods, we must evaluate the average annual temperature from a geological perspective. Milankovitch's theory explains that changes in the planet's climate occur after the periodic occurrence of glaciations. This is where major ice ages and short interglacial periods have appeared. We are currently in an interglacial period.

These periods of glaciations occur because of the combination of 3 cosmic cycles in which the Earth's orbit changes from circular to elliptical and vice versa. One of the first cosmic cycles is recorded to have occurred between 90.000 and 100.000 years ago. This is when the Earth's orbit changed from circular to elliptical and vice versa. Another cosmic cycle occurred about 26.000 years ago and determined the wobble of the Earth's rotational axis. Finally, another cosmic cycle occurred 41.000 years ago, during which the inclination of the Earth's axis with respect to the plane of its orbit oscillated between 22.5 and 24.5 degrees.

Cosmic cycles

All these changes in the movements and axis of the Earth are the main producers of glaciations. It must be taken into account that the phases in which The Earth's orbit is circular and hardly changes throughout the year. However, when the orbit is elliptical, a closer proximity occurs at certain times of the year. Today, we know that the Earth's orbit with respect to the sun is elliptical, although it is not at its maximum eccentricity. When the Earth passes through perihelion, the closest orbital point to the sun, it occurs at the beginning of January. This is when it is winter in the Northern Hemisphere. On the other hand, when it is at aphelion, it is summer in the Northern Hemisphere, even though it is at its furthest position.

When the linked cosmic cycles occur, this arrangement changes; over time, perihelion occurs coinciding with the southern winter instead of the northern winter. Therefore, it is known that the key to the influence of these orbital changes on the onset of ice ages is consistent with the Milankovitch model. Everything seems to be related to the period in which the orbit is circular and the distance from Earth barely changes. In this situation, warm summers like the current ones do not occur. On the other hand, warm summers like the current ones occur during the periods in which the orbit is elliptical and has its maximum eccentricity.

When the orbit is more circular It prevents the snow from melting and gradually accumulates year after year. This puts the Earth on the path to a new Ice Age. This suggests that what determines glaciations is not harsher winters, but cooler summers. From this, we can conclude that, due to cooler summers, the ice surface will not melt, and the thickness of the polar ice caps will increase each year until a period of glaciation ends.

Known ice ages on Earth

These are the different glaciations that have been known on our planet throughout history:

• The first glaciation is known as Huronian. It took place approximately 2.400 billion years ago. It lasted about 300 million years and was the longest of all.
• The second glaciation is known as Cryogenic. It is possibly the most severe and occurred approximately 850 million years ago. It was responsible for the subsequent Cambrian explosion.
• The third glaciation is known as Andean-Saharan. It occurred approximately 460 million years ago.
• The fourth glaciation is named after Karoo and it happened about 350 million years ago.
• In the current glaciation, called Quaternary glaciation, It has seen glacial periods of about 40.000 years.

I hope that with this information you can learn more about glaciations.