Originally posted by SGalisa
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2012: Magnetic Pole Reversal Happens All The (Geologic) Time
Source: NASA
Scientists understand that Earth's magnetic field has flipped its polarity many times over the millennia. In other words, if you were alive about 800,000 years ago, and facing what we call north with a magnetic compass in your hand, the needle would point to 'south.' This is because a magnetic compass is calibrated based on Earth's poles. The N-S markings of a compass would be 180 degrees wrong if the polarity of today's magnetic field were reversed.
Therefore, the poles as we call them North Pole and South Pole will still be North Pole and South Pole except that due to a reversal of the polarity, the magnetic North will be South and the magnetic South will be North.
The Earth as a slightly elliptical ball still very much up the way it's always been. It won't suddenly turn upside down.
Sediment cores taken from deep ocean floors can tell scientists about magnetic polarity shifts, providing a direct link between magnetic field activity and the fossil record. The Earth's magnetic field determines the magnetization of lava as it is laid down on the ocean floor on either side of the Mid-Atlantic Rift where the North American and European continental plates are spreading apart. As the lava solidifies, it creates a record of the orientation of past magnetic fields much like a tape recorder records sound. The last time that Earth's poles flipped in a major reversal was about 780,000 years ago, in what scientists call the Brunhes-Matuyama reversal. The fossil record shows no drastic changes in plant or animal life. Deep ocean sediment cores from this period also indicate no changes in glacial activity, based on the amount of oxygen isotopes in the cores. This is also proof that a polarity reversal would not affect the rotation axis of Earth, as the planet's rotation axis tilt has a significant effect on climate and glaciation and any change would be evident in the glacial record.
Thus has no effect on the climate or causes it to change.
However...
Climate Change Is Moving the North Pole
Source: National Geographic Society
As ice melts and aquifers are drained, Earth's distribution of mass is changing—and with it the position of the planet's spin axis.
[...]
Earth turns around an axis like a giant spinning top. The places where that invisible axis intersects with the planet's surface are the north and south rotational poles. Due to Earth's wobble on its axis, these spots drift in roughly decade-long cycles. (All this motion is a completely separate mechanism from the behavior of the planet's magnetic poles, which also reverse periodically over the course of millions of years.)
[...]
For at least a decade, scientists have suspected that the massive amounts of melting taking place in glaciers around the world could significantly redistribute mass on Earth. That's particularly true when it comes to the huge ice sheets over Greenland and in the West Antarctic.
If ice disappears from one part of the spinning Earth and resettles elsewhere as water, the planet shifts on its axis toward the place where it lost mass.
Basically, the magnetic poles do not impact climate or the change thereof, so you are wrong there.
The melting of the icesheets does impact the pole-axis on which the Earth spins, which impacts climate models across the globe, and can give scientist a better look at the change happening.
Originally posted by SGalisa
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Ever hear of Carbon-14 dating? It's pretty nifty.
Accuracy is iffy sure. I mean, it's impossible to put an exact age on stuff but I'm fairly certain the dates we do get are pretty accurate. The dating science has come a long way since the first days of its use.
And I don't necessarily have to know dates. You could easily have said Stone Age, Bronze Age, Iron Age. Or if you like it better 10.000 BC or 5000 BC. I'm fairly well known with those timeframes and who was running around where, doing what. I mean, we do have a lot of material at our disposal to form a pretty interesting image of the period.
Even what our forefathers/mothers had for breakfast. Or better how they buried their dead.
Just last week, learned about a new group of people living on Mallorca between 1500 BC and approximately 200 AD. They sped through the Bronze and Iron Age, thanks to their interactions with the Phoenicians and Punics. And then the Romans came and they disappeared.
Sadly, they left no markings or writing.
Anyhoodle... what I wanted to know was, how far do I encompass mankind since the earliest polution occured during the Stone Age -- I kid you not -- by burning fires inside caves.
However, that was nothing compared to the industrial age, or the Romans hacking their way through every forest in Europe.
I mean, Stonehenge is now situated, in the middle (sort of) of a large empty plane. There used to be forests there. Lots of trees -- all gone though. The Celts also helped obviously.
Originally posted by SGalisa
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Originally posted by SGalisa
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Well, you know, palaeontologically speaking...
Sidenote: Was my first choice, and then Archaeology. Equally fascinating.
And much like in other fields, the more dinosaur skeletons we find, or stuck in something somewhere. The more we learn about them.
They had feathers, which is sooooooo cool.
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