On Christmas day, while people in Italy drink hot chocolate under their blankets, Brazilians are at the beach drinking some iced beverages. All of this could however change in the future.
Imagine a world where the snow never stops falling, the cold never fades, and survival becomes a daily struggle. If a long winter period strikes the Earth, we would find ourselves in a post-apocalyptic state.
Resource scarcity would be the first issue to hit us. The ground would freeze solid, crops would perish, and food would become scarce. To survive, we would need to choose between hoarding and sharing. Those who choose to hoard would become isolated and eventually come to ruin.
Scientists think we might find ourselves in this situation in the years to come. There are cycles on Earth that are in conflict: periods of hot weather alternate with cold ones.
However, these conflicts won’t last forever: in the future, the conflict will eventually stop, and a long winter will come.
But how do these cycles work?
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Surrounded by Cycles
Let’s start by saying that, here on Earth, we are basically surrounded by cycles. Let me explain.
Our lives literally revolve around them: a series of events that are repeated regularly in the same order. There are hundreds of different types of cycles in our world and in the universe. Some are natural, such as the change of the seasons, annual animal migrations, or the circadian rhythms that govern our sleep patterns. Others are human-produced, like growing and harvesting crops, musical rhythms, or economic cycles.
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The Cycle of Seasons
You might already know why we have seasons, but I think it’s worth reviewing, as this will serve as a starting point to understand the main topic of this video, the Milankovitch Cycles.
The reason why we have seasons is due to the revolution of Earth around the Sun and the inclined axis. As our planet orbits the Sun, the tilt of its axis causes different parts of the world to receive varying amounts of sunlight. This results in the changing of seasons in different parts of the world at different times of the year.
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The Milankovitch Cycles
So, the presence of seasons is due to the particular configuration of a planet’s axial tilt with respect to its orbiting plane around the host star. But, as the Serbian scientist Milutin Milankovitch pointed out a century ago, this is not the only factor capable of having an impact on the Earth’s weather and climate.
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Changes in Eccentricity
The eccentricity gives information about the shape of an orbit. When it is zero, the orbit is a circle. The more you depart from zero, the more stretched and elliptic your orbit is.
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Changes in Obliquity
But that’s not the end of it!
This genius…uhm…Milankovitch also took into account something else: the obliquity and the axial precession.
The obliquity is the angle between the plane of the Earth’s orbit and that of the Earth’s equator.
This tilt has varied between 22.1 and 24.5 degrees over the last million years. The greater the tilt, the more extreme our seasons are.
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Axial Precession
For what concerns axial precession let me first explain what it is.
I don’t know if you are aware of this, but the Earth wobbles slightly on its axis like a spinning toy top. This wobble, caused by tidal forces from the Sun and Moon, affects Earth’s rotation and is known as axial precession. This cycle lasts about 27.7 thousand years and makes seasonal differences more extreme in one hemisphere and less extreme in the other.
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Milankovitch’s Crazy Prediction
The small changes set in motion by Milankovitch cycles operate separately and together to influence Earth’s climate over very long timespans, leading to larger changes in our climate over tens of thousands to hundreds of thousands of years. .
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Predictions Accuracy
Making predictions when it comes to long-term climate on planet Earth is no picnic.