Milankovitch cycles: Natural causes of climate change

Explanation of natural causes of climate change, like Milankovitch cycles, volcanoes and sunspots.

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The average temperature on Earth has always fluctuated. Millions of years ago, for example, it was on average 8 degrees warmer on Earth. There were also ice ages thousands of years ago and the average temperature on earth was 2 degrees lower.

How did these temperature differences arise?
First, the sun plays a role. When the sun is more active, sunspots can be seen. This can make it a little warmer on Earth, but this only involves a tenth of a degree of heating. The current global warming can therefore not be explained by a change in the activity of the sun.

Volcanoes also play an important role. During a violent eruption, a lot of ash is released into the atmosphere. This ash, if it enters the atmosphere high enough, can remain in the atmosphere for a long time and block the sunlight. For example, the eruption in 1815 of the Indonesian volcano Tambora in 1816 caused the global temperature to drop sharply and 1816 was called the "year without summer."

Although in the short term the volcanoes cause a temperature decrease, volcanoes cause a temperature increase in the long term. Volcanoes emit the greenhouse gas CO2, which causes the temperature to rise. The earth was once a planet full of ice, but due to a lot of volcanic activity, a lot of CO2 was emitted and the temperature on earth slowly increased.

Milankovic's variables are a final natural influence. Milankovic thought that the temperature on earth was influenced by 3 variables related to the position of the earth relative to the sun. In short, the point is that if the northern hemisphere receives less energy from the sun in the summer, the ice on the North Pole will not melt and an ice age may arise.
First, the Earth does not orbit the sun in a circle, but in an ellipse shape, in which the sun is not centered. This is called eccentricity. The point where the Earth is closest to the sun is annually at the beginning of January.

So in July, the Earth is farthest from the Sun. This is summer in the Northern Hemisphere. Because of the distance, the earth receives less energy from the sun, the ice in the Northern Hemisphere melts less quickly.
This could be the beginning of an ice age.
If there is a circular shape, the Earth is closer to the sun at the beginning of July. This gives the Northern Hemisphere more energy, and the ice melts.

This prevents the formation of an ice age. The eccentricity changes approximately every 100,000 years.
The second is obliquity. This is the tilt of the earth's axis relative to the sun. The Earths axis has a tilt of 23.5 degrees, but this changes between 22 and 24.5 degrees. The wider the angle, the more the northern hemisphere turns toward the sun in summer and the more ice melts. The smaller the angle, the less ice melts in summer and the greater the chance of an ice age. The obliquity changes approximately every 41,000 years.
The third is the precession. This is a toll movement around the Earth's axis that changes every 26,000 years. Here the first two effects are amplified or limited depending on the eccentricity and obliquity.

Now that you have learned how natural fluctuations in the climate arise, we can investigate the consequences of climate change for the earth.