Earth's climate cycles and an anomaly

The Earth is not still. Inside and outside it there are movements on different scales of size and time. Its cosmic position, not only in its planetary system, but also in the Milky Way, makes it possessed of natural cycles, which inevitably happen without, from an anthropocentric perspective, human actions influencing it.

Among these natural cycles are climate cycles, which are constant, long-lasting changes in temperature that modify the atmosphere, reliefs and waters, and from which the life of thousands of plants, animals and other organisms has emerged and died out, species that survived, evolved or that we know only through vestiges, others of which there will never be a trace and some more that do not even exist in the imaginary. But we must not confuse Earth's natural climate cycles with current climate change, whose main trigger is humans, is short-lived and, rather than joining a cycle, catalyzes the end of beings and ecosystems irreversibly. Here's an explanation to avoid confusion.

Terrestrial natural climate cycles

These are repetitive periods in which the planet heats up or cools depending on the amount of solar radiation it receives (insolation) over millions or billions of years. The effects of these temperature changes have caused five long ice ages or glaciations, with shorter warm interglacial periods, from 2.4 billion years ago, over the Earth's at least 4.5 billion years old; that is, the variations in cold and heat have been repeated five times, hence they are cycles.

The Serbian geophysicist Milutin Milanković used mathematics to understand the relationship of long-term climate changes with Earth's movements with respect to the distance from the Sun. Thanks to what he discovered, we know how variations in insolation affect Earth's climate. He identified at least three movements that cause variations in insolation:

Eccentricity: The amount of solar radiation that the Earth receives in relation to the shape of its orbit: an almost circular one and a slightly elongated one in the shape of an ellipse. The quasi-circle and ellipse transition and vice versa is slow, about 98,000 years, and there is a distance variation of only 3% between the two and 6% of solar energy reception. The more elliptical the translational orbit, the planet will receive a little more radiation because there will be a point closer to the Sun. Currently, we are traveling in an almost circular orbit, that is, in a year we receive the same amount of solar energy.

Obliquity: Inclination of the planet's axis of rotation with respect to its plane of orbit (its translation around the Sun); that is, this axis is also in motion, like a metronome that tilts slowly from one side to the other for 41,000 years, therefore, its angle in degrees varies, between 22.1 and 24.5°. There is more sun exposure in the Northern Hemisphere and less in the Southern Hemisphere when the axis tilts towards the Sun, and vice versa, so both hemispheres get hotter than the other in the seasons of the year. Today the axis is 23.4 degrees; this implies that the Northern Hemisphere has the longest day and the shortest night of the year, and the Southern hemisphere has the shortest day and the longest night of the year.

Precession: The rotation axis tilts, but it also changes orientation as the planet wobbles under the force of attraction with the Moon, Jupiter, Saturn, and of course, the Sun. Like a spinning top, the tip of the shaft forms a circle when it rotates tilted, over a period of approximately 25,771.5 years. The current perception causes, for example, that the Northern Hemisphere receives more solar radiation during winter.

By combining the three movements over billions of years, solar exposure changes across the planet, with certain trends in the polar and equatorial zones. Some regions tend to be colder than others temporarily, while the entire globe has constant high or low temperatures.

As a habitat, then, the Earth moves and, with it, mutates inside. Ice covers its surface during glaciations, melts during interglaciations and appears again in a new glaciation. This has happened with and without human presence since the beginning of the Earth, because Homo sapiens we began to walk on the planet just 200 or 350,000 years ago (not a million) and, as a species, we have survived two ice ages, within the Quaternary geological period, which began 2,588 million years ago and continues. In other words, it has been estimated that in the Quaternary geological period, there have been four main glaciations, of which we have experienced two. The last one ended 10,000 years ago and was followed by an interglacial phase, less icy and warmer, in which we are still in.

During this last glacial period, ice was prominent in the north and south of the planet. Some humans who managed to withstand temperatures, particularly those in southern Ethiopia, moved to high mountains, 4,000 meters above sea level, the Bale Mountains. There, despite the cold, the high frequency of rains and the low level of oxygen, they adapted physically and culturally, because, according to a study by the Martin-Luther-Universität Halle-Wittenberg, in Germany, this place was far from glacial territories, so the Homo sapiens they developed new capacities for their survival, such as their adaptation to places with lower oxygen levels than usual. They had enough water due to the progressive melting of the ice that occurred over the years, they ate the fats and meat of mammals, such as giant rodents and woolly mammoths, in the absence of vegetables, and with this they obtained the necessary calories to face adverse conditions. Due to human consumption and weather conditions, some giant mammals, in turn, succumbed: saber-toothed cats, terrestrial sloths or mastodons, to name a few. Smaller ones survived, including chimpanzees, serfs, bears, kangaroos and felines.

In the same way, in the glaciations prior to the Quaternary era, countless living beings emerged and disappeared, for example, primitive, multicellular, amphibians, reptiles, the first mammals, flowering plants... Planet Earth, then, houses lives that adapt or die in certain scenarios and atmospheric conditions. They are lives capable of also modifying their environment, of altering ecosystems and their symbiosis with different species, and well, humans have done it.

Climate change caused by human factors

Although it may seem like an easy explanation, the natural terrestrial cycles that we have just explored are not the primary factor of the climate change we are experiencing today because of these reasons:

- Current climate change is associated with the greenhouse effect caused by the burning of fossil fuels during the first Industrial Revolution; therefore, the origin is anthropogenic, that is, due to human causes.

- The oldest record of the increase in carbon dioxide in the atmosphere is 1830; that is, recent climate change has been going on for 191 years. In that time, the planet's climate has increased by 1.2o C. In 1880, the global temperature of the Earth's surface and seas was -0.16o C; and in 2020, 1.2o C. The World Meteorological Organization (WMO) estimates that in 2024 it will be 1.5o C. So, the pace of change in Earth's climate is accelerating (measured in decades), not slow, as happens in natural cycles (measured in thousands or millions of years).

- Natural cycles are related to the increase or decrease in the amount of solar radiation reaching the planet, but in the last 40 years, this amount has decreased. Consequently, global warming cannot be attributed to an increase in solar radiation.

- We are in an interglacial period: between a past glacial period and one that could occur in thousands of years. Therefore, we would be heading towards an increasingly cold global climate, not hot, despite the fact that the interglacial periods are not icy, but with cold and warm states.

In this context, humans, born from a combination of effects of changes in temperature and terrestrial matter, have altered the ecosystems on the planet that hosts us, inevitably now in a more conscious way. Excessive emissions of carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and water vapor, as a result of the burning of coal, oil and other fuels, deforestation and other activities, have accelerated not only our physiological adaptation to temperature variations, especially high temperatures, but also that of other living beings. Some species have succeeded, but others have fallen abruptly, constituting what has been called the sixth mass extinction in Earth's history.

The Circle of Life

In 2017, the University of Washington published a study in which they said that, in the face of climate change and global warming, “many amphibians, mammals and birds will move to colder areas, outside their normal ranges, as long as they find space and a long trajectory between our urban developments and growing cities”, but what will happen to fish?

Assuming that not all organisms are equally sensitive to climate changes, a group of scientists from that university studied environmental patterns that would put 3,000 species of fish at risk in oceans and rivers. They found, for example, that freshwater fish at high altitudes in the Northern Hemisphere will be at greater risk when the waters have a higher temperature. They will have to move quickly to other places to adapt to changes or they will be forced to adapt immediately without moving, which has a high failure rate. Meanwhile, fish that live in the tropics are more used to warm climates, however, they can only hold out so long before they also need to move to cooler waters. “Fish will migrate, adapt or die as temperatures continue to rise.”

The example of fish survival is, therefore, one of many that demonstrate that climate change is going fast and that it does not correspond to a natural cycle of either terrestrial temperature or life. The effects of climate change, then, transform the behavior and coexistence of all living organisms, both on land and under water. Until now there is no clear record of genetic or morphological changes, but of their life cycles, such as different periods of hibernation, mating or migrations.

If, even out of mere curiosity, we observe geographical models based on satellite images, it is possible to visualize “from the third person” the atmospheric changes on the planet in real time, such as the formation and thawing of the poles, the decrease of water in rivers or seas, or the growth of the hole in the ozone layer. With that perspective, within the planet, we can witness more closely some of the foreseeable impacts of climate change:

- Sea level rise

- Increase in endangered animal and plant species

- Decrease in water reserves

- Disappearance of glaciers

- Loss of wetlands

- Increase in malnutrition and infectious diseases and epidemics

- Increase in the mortality and morbidity rate

- Intensification of heat waves and droughts

The human hand catalyzes the planet's natural cycles, so far to supply itself with more resources. In modern philosophy, the meaning of has been rescued inhabit such as “taking care of” or “looking for”, and that of Take care such as “protecting”, “guarding” or leaving something in the essence of the place you inhabit or live in. Since we inhabit the planet, our behavior affects it. “Mortals live to the extent that they save the earth [...]. Salvation doesn't just tear something out of danger; to save properly means: to block something's entrance to its own essence. Saving the Earth is more than exploiting it or even ruining it. Saving the Earth is not taking possession of the land, it is not making it our subject, from where only one step leads to limitless exploitation”.

This Heideggerian message, in other words, explains that for mortals to properly inhabit the Earth (and the Earth), we allow its conditions, seasons, surfaces and elements to be as they are, without damaging them. And since we are on this planet, we must learn to inhabit it, Take care of him; to learn to adapt to it to adapt or protect it, and thus to have a pleasant life and death in it, which is the only certain objective of the human being. “Mortals inhabit to the extent that they drive their own essence - being capable of death as death - to the use of this capacity, to make it a good death.” In that sense, from any scientific or humanist perspective, the message is similar: organisms inhabit a planet with cyclical natural characteristics and, if there is consciousness, it is possible to avoid or mitigate further damage, in order to coexist in life and death in the most beneficial way possible for the Earth itself.

References

Buis, Alan (2020). “Milankovitch (Orbital) Cycles and Their Role in Earth's Climate”. NASA News. https://climate.nasa.gov/news/2948/milankovitch-orbital-cycles-and-their-role-in-earths-climate/

Heidegger, Martin (2007). “Build, Inhabit and Think”. In The question about the technique (and other texts). Folio: Barcelona. pp. 43-63

Lise Comte, Julian D. Olden. “Climatic vulnerability of the world's freshwater and marine fishes”. Nature Climate Change, 2017; TWO: 10.1038/nClimate3382

Nerilie, J. Abram, et. al. (24 August, 2016). “Early onset of industrial-era warming across the oceans and continents”. Nature. https://www.nature.com/articles/nature19082

NSF. “Large Ice-Age Mammal Extinctions: Humans and Climate the Culprits”. NSF News. https://www.nsf.gov/news/news_summ.jsp?cntn_id=122133

Ossendorf, Götz (2019). “Middle Stone Age foragers resided in high elevations of the glaciated Bale Mountains, Ethiopia”. Science; 365 (6453): 583 OF: 10.1126/science.aaw8942