Natural Climate Change: What and How?
- Sabrina Kainz
- Jan 26, 2016
- 4 min read
Okay firstly, not even going to talk about how long it has been since i updated. Yeahhhh.
Moving on...
CLIMATE CHANGE.
Ill just be talking about how climate change occurs naturally on a 100,000 year cycle, not any modern human altering factors. The title may be a bit confusing, but just to make things easier, climate change refers to the warming OR COOLING of the Earth. While global warming is warming (duh), things like the ice ages are the cooling of earth.
It is a known fact that our climate on Earth has changed very much over time. Im not talking months here. Im talking thousands of years. Every ten thousand years (give or take), our Earht changes into a warm interglacial period, or a cold glacial period. So before we get onto why it happens, imma talk about how we actually know it happens. This splits into two categories: the distant past, and the recent past.
The Distant Past - the REALLY old evidence
1. Fossils!
- the beautiful remains of plants and animals tell us where different kinds of animals lived as well as when
- so when we find the bones of a penguin in the middle of the Sahara desert, we know it must have once been cold. (please dont use that as an example. it was just to get the concept)
2. Fjords :P
- these U shaped valleys are created from the movement of glaciers erroding the sides of a mountain
- they basically will tell you if the climate was hot or cold, because in a cold period, if wouldnt have melted as much, and we can see when there was alot of movement
3. Ice Cores
- how to: drive a giant tube into some antarctic ice and pull it out to look at more ice!!!
- but seriously, cores are the most reliable evidence we have of climate change, as we can see the C02 concentration and isotopic levels in different periods of time.
- From the CO2 sampling we can plot out what the temprature was like a thousand million billion years ago
- also they can tell us if any big events like volcanic eruptions occured from layers of ash trapped in there.
4. Tree Rings
- Over summer in Yosemite i was one of the lucky few who was able to see the thousand year old Sequioa trees. These things are hundreds of meters tall, but what we are interested in are the 17 meter diameters.
- trees grow a new layer every year, thicker in warm climates, thinner in the cold.
- from this we can see whether the climate was warm or cold
The Recent Past
5. Photographs and Painting
- visually representations of the environment a hundred years ago can give as a look into what the tempratures were like
- for example; a painting of people skating on the river Thames??? Must have been colder.
6. Written records
- how much of this crop was grown? how many birds migrated? how much it got hotter? everything written down basically. Even stories.
Now we know how we know it happened, we can move onto how it actually happens.
Three Theories: Eruption, Sunspots, Orbital
Orbital makes more sense to climate change. the others are conditional. here:
The Eruption Theory
When you think about a 200 million years ago, we think of dinosaurs and volcanoes dominating the Earth. And of course these volcanoes erupt and kill stuff! So when a giant volcano erupts, so much ash is bursted into the atmosphere that is blocks out the sun and kill the plants and kills the animals and everything dies. Why? Becuase there is no warmth from the sun. it is what provides us with food and warmth. So in these periods of time, climates become increasingly colder.
E.g. Tambora, Indonesia, 1815
The Sunspots Theory
The natural phenomena of giant black dots popping up on the sun's surface is an indicator of the sun acting up. When we see these, more solar energy is released and makes its way to earth. At this time, the auroras will begin becoming stronger. This happens on an eleven year cycle, so that doesnt explain the big climate change.
The Orbital Theory
This is the one that checks out best. We are all orbiting around the sun. Most of the time we are in a circle. But sometimes the orbit changes into a more oval shape. When this happens, the Earth is closer and warmer to the sun at some times, and far away at other. Its hard to explain just look at the photo. :P Then we have the tilting of Earth, which creates seasons, but can also add to th
e longer term climate. And finally, ever so often the Earth wobbles on its axis like a spinning top.
so these three factors are what causes intergalcial/glacial period.
We call this the Milankovitch Cycle:
1. Ellipse shaped orbit
2. Tilted axis
3. Wobbling
And guess what. this happens on a 100,000 year cycle, fitting perfectly with climate change on Earth...
So there we have it. Yeah yeah, ill be getting on to more geology and rock based posts in the future, but i thought this would be good for now, especially because i needed the revision material for an upcoming test...
If anyone is reading, thank you :)
till next time,
Sabrina :P
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