400,000 Years 12C Variation

Now lets look at what the glacial cycles looks like by zooming into just the last 400 thousand years where we can very nicely see the last four glacial cycles.

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400 thousand years is enough time to give us a sense of what each glacial period looks like and where we are in our current cycle.

A few things to note. The cycles are fairly regular but no two cycles are exactly alike. The time spent in the more “comfortable” ice free period is only about 20% of the cycle. Our current warm period seems to be past the halfway point yet so far, we experienced a relatively narrow range of temperature changes compared to previous cycles. All the scary man-made climate change occurs in the red blob at the far right where the temperature has been going up and down around the zero line for the past 10,000 years. It is pretty hard to see 100 years on this time scale as it would be the last edge of the blob but it is worth noting that it is well below the extreme temperature highs of previous cycles.