Climate Change
Hiya!
If there's one thing geography has taught me, the ability to keep working even though I can't think of a worse way to spend my time. However I can't lie this topic fits in with some sort of science somewhere! Hope you warm (globally) to this topic as much as I did. Happy reading!
We all know about the typical causes of global warming like carbon dioxide emissions and methane from product manufacturing but often we discount the natural causes of global warming in which few people know about. Whilst the human factors in the last industrial centuries have emphasised the rates of global warming, much of the temperature changes we see today are natural.
Firstly, it's important to know about the Milankovitch cycles in which Serbian mathematician, Milutin Milankovitch, proved the Earth's orbit, axial tilt and axial precision played an important role in seasons and how the Earth's climate is subsequently affected. Here are his three concepts;
If there's one thing geography has taught me, the ability to keep working even though I can't think of a worse way to spend my time. However I can't lie this topic fits in with some sort of science somewhere! Hope you warm (globally) to this topic as much as I did. Happy reading!
We all know about the typical causes of global warming like carbon dioxide emissions and methane from product manufacturing but often we discount the natural causes of global warming in which few people know about. Whilst the human factors in the last industrial centuries have emphasised the rates of global warming, much of the temperature changes we see today are natural.
Our lovely Earth (NASA) |
Firstly, it's important to know about the Milankovitch cycles in which Serbian mathematician, Milutin Milankovitch, proved the Earth's orbit, axial tilt and axial precision played an important role in seasons and how the Earth's climate is subsequently affected. Here are his three concepts;
- Orbital eccentricity- this is the idea (well it's true) that roughly every 100,000 years, the Earth;s orbit changes from a more circular to elliptical shape causing insolation (radiation from the sun) to be varied. If you picture an ellipse, you will know that the centre will be closer to some parts of the ellipse and further from other parts which is true with the Earth as during orbit; sometimes the Earth will be much closer and some parts it will be significantly further away from the sun. This causes a cooling effect overall because the Earth receives less insolation and cools down, despite the counter-intuitive high insolation at some points.
- Milankovitch also showed that over a 41,000 year cycle, the Earth tilts on its axis from 23.5 degrees to 22-24.5 degrees. This affects solar output as when the angle increases, there are more obvious differences between poles and seasons are more definite. On the other hand, if the angle decreases, the tilt is less strong and the insolation is more balanced causing less obvious seasons (basically everywhere becomes like Africa). In summary, if the angle increases it will cause the Earth to cool, if the angle decreases, the Earth's climate will rise.
- Milankovitch's last cycle shows that the Earth's axis wobbles, over 21,000 years, the Earth's climate will begin to cool. This wobble exposes different sides of the hemispheres to solar input which causes the Earth to be exposed at different rates. The problem with this is that certain areas are exposed less and less which overall causes a cooling effect.
A really pretty sunset picture I wish I had the ability to take(Julian Di Majo) |
In a more short-term change, the more solar output ,the warmer it will be as the insolation will increase. The sun's output is never constant and the most obvious cause of global warming is the effect of sun spots. The sun's radiation varies in a cycle of roughly 11 years. In fact, the effects of sun spots and solar radiation are suggested to be the cause of 20% of 20th century global warming.
Additionally, major volcanic eruptions emit material into the stratosphere. The sulphur dioxide forms a haze of sulphate aerosols, which blocks and reduces the amount of insolation reaching the inner layers of the atmosphere like the troposphere. This reduction of insolation causes a the temperature to decline slightly. A common example was the eruption of Tambura which led to a temperature drop of between 0.4-0.7 degrees C in the summer of 1816.
Erupting volcano (Marc Szeglat) |
Finally, asteroid collisions can also cause large short-term problems. As they collide with the Earth. thousands of tonnes of ash and dust are released into the atmosphere. Just like the volcanic eruptions, this dust and ash blocks the insolation in the stratosphere and will cause the Earth to cool down for a period of 5-10 years.
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