The axis of the world is the imaginary line around which the Earth rotates in its rotational motion. The extremes of this axis are the North and South geographic poles. It is common knowledge, as it is taught in school, that this axis is inclined with respect to the plane of the Earth’s orbit, and that this inclination is responsible for the seasons on Earth.
The inclination of the Earth’s axis about the plane of its orbit, also called obliquity of the ecliptic, is about 23.4 to 23.5º, its present value being 23.43º. Think of a spinning top spinning, in its little pitches as it spins, and we will understand, by similarity, that the obliquity of the ecliptic is slightly variable due to oscillation of the Earth’s rotation through its axis. This oscillatory motion is called nutation and has a period of almost 19 years. In addition, in the translational motion of the Earth around the Sun, the extension of the world’s axis towards the celestial sphere is not always directed towards the same point in the sky. At present, it is directed towards the pole star, but this point varies gradually so that it describes a circle. It takes 25800 years for this circle to be completed. In about 12000 years the Earth’s North Pole will be directed towards the bright star Vega, which will mark the North on our planet. This movement of the Earth’s axis with a period of 25800 years is called precession (the phenomenon is identical to that of a spinning top whose axis of rotation does not coincide with the vertical).
When we analyze the concept that the tilt of the Earth’s axis affects the climate, the reality is more complex than we can imagine by looking only at the surface of what is happening. It is true that there have always been times of glaciation. And even mankind has lived through them. But it is not climate change that is the concern, but rather that it is accelerating with the help of humans. In about 150-200 years we have climbed the mountain of climate change too fast because of our new ways of life. «That’s why we are told we have to prevent the rise from being so rapid. If the rise is over 5,000 years, we have time to adapt and change. But if it happens overnight, how do I react? I don’t have time,» adds Santisteban.
With us or without us, the Earth’s climate will change – and survive our passage through the planet – as it has done every 120,000 years, Mediavilla and Santisteban explain. Only in those other epochs everything has gone much slower. Much, much slower. And there has been time to get used to it and evolve in order to survive.
The problem, therefore, is ours. «The problem is that the human being is not used to the conditions that may come upon us. So, our way of life may change completely,» Santisteban points out. «The climate is important for us because we live under certain conditions. And when they change, there are many changes. Can we imagine living now without heating? But humans have lived without heating for a long time before,» says Mediavilla. Now we have many comforts, but would we be willing to do without them if necessary?
«What people don’t realize is that we’re putting ourselves at risk,» Santisteban comments.» «To the species,» Mediavilla points out. «From the point of view of evolution, extinctions have always occurred,» adds the IGME researcher. «Species appear and disappear; the Earth goes on,» he says.
I invite you to read Matías’ post with the topic of the day.
Finally, I encourage everyone to reflect on the concept of the day. No one else but us can re-signify our own being