I have just commenced reading a book that focuses on the past 20,000 years of human development as seen through the eyes of archeology. It appears useful and once I have properly gotten into it I will do a review for you all. What really jumped out at me however, was a chart that maps the oxygen isotope ratio in the ice caps.
Variations in the ratio is a proxy for whether the global climate is warmer or colder. It is also reasonably reliable over the twenty thousand year time span as is the ability to take ice samples in the Antarctic covering the same period. I think that we can accept the results as useful over the designated time span. What certainly can be trusted is the observed variability ratio.
What stands out in the chart is that the Pleistocene Nonconformity is more abrupt than perhaps understood before. The global climatic shift was not just from a seriously cooler climate to the our warmer era known as the Holocene, but from a clearly very volatile regime of shifting worldwide climatic conditions to the current regime of very low variability.
The chart is utterly compelling. For twelve thousand years the chart has flat lined showing minimal variability. Prior to that, not only was the average temperature colder, it moved back and forth over a wide range of variability that is at least an order of magnitude greater than is apparent today.
In reality, this confirms the geologic nature of the Pleistocene Nonconformity more that any other argument. A one million year regime that included a huge northern icecap ended in a couple of thousand years due to the ice cap been shifted thirty degrees into a nonsustaining environment that also was able to prevent the mere rebuilding of the icecap in one place as it was been melted in another. We had an incredibly lucky throw of the dice that has actually likely seen the global climate restored closer to the type of climate experienced over the past billion years.
My readers will want to revisit my posts under Pleistocene Nonconformity back in June and July.
For the record, the onset of the northern ice age coincides with the establishment of the Panama - Central American land bridge that closed off the Atlantic a million years ago. A pretty unique event in global geologic history. It has also taken a pretty unique configuration to prevent the establishment of a full icecap at the pole during our era. It is principally dependent on a large imbalance of northern equatorial waters been forced into the Arctic. It is almost an engine.
That engine has made the northern hemisphere hugely habitable to ourselves. Without it, North America, Europe and all of temperate Asia becomes largely uninhabitable, as was true during all of the Pleistocene.
Perhaps now we understand better why humanity broke out of the tropics only ten thousand years ago. Prior to that it was not really a very good option. All the advantages of the temperate climate were simply not available and in those small areas were they existed, wide climate swings made any culture other than game hunting terribly vulnerable. Our so called climate shifts are trivial by comparison.
Thus, prior to the shift from Pleistocene to Holocene, mankind could hope to establish a proto civilization in only the tropics and semi tropics. This included all of Africa, the Indonesian Plain and India and not much else.
The advent of the Holocene gave us the world and the possibility of agriculture as we know it.
Variations in the ratio is a proxy for whether the global climate is warmer or colder. It is also reasonably reliable over the twenty thousand year time span as is the ability to take ice samples in the Antarctic covering the same period. I think that we can accept the results as useful over the designated time span. What certainly can be trusted is the observed variability ratio.
What stands out in the chart is that the Pleistocene Nonconformity is more abrupt than perhaps understood before. The global climatic shift was not just from a seriously cooler climate to the our warmer era known as the Holocene, but from a clearly very volatile regime of shifting worldwide climatic conditions to the current regime of very low variability.
The chart is utterly compelling. For twelve thousand years the chart has flat lined showing minimal variability. Prior to that, not only was the average temperature colder, it moved back and forth over a wide range of variability that is at least an order of magnitude greater than is apparent today.
In reality, this confirms the geologic nature of the Pleistocene Nonconformity more that any other argument. A one million year regime that included a huge northern icecap ended in a couple of thousand years due to the ice cap been shifted thirty degrees into a nonsustaining environment that also was able to prevent the mere rebuilding of the icecap in one place as it was been melted in another. We had an incredibly lucky throw of the dice that has actually likely seen the global climate restored closer to the type of climate experienced over the past billion years.
My readers will want to revisit my posts under Pleistocene Nonconformity back in June and July.
For the record, the onset of the northern ice age coincides with the establishment of the Panama - Central American land bridge that closed off the Atlantic a million years ago. A pretty unique event in global geologic history. It has also taken a pretty unique configuration to prevent the establishment of a full icecap at the pole during our era. It is principally dependent on a large imbalance of northern equatorial waters been forced into the Arctic. It is almost an engine.
That engine has made the northern hemisphere hugely habitable to ourselves. Without it, North America, Europe and all of temperate Asia becomes largely uninhabitable, as was true during all of the Pleistocene.
Perhaps now we understand better why humanity broke out of the tropics only ten thousand years ago. Prior to that it was not really a very good option. All the advantages of the temperate climate were simply not available and in those small areas were they existed, wide climate swings made any culture other than game hunting terribly vulnerable. Our so called climate shifts are trivial by comparison.
Thus, prior to the shift from Pleistocene to Holocene, mankind could hope to establish a proto civilization in only the tropics and semi tropics. This included all of Africa, the Indonesian Plain and India and not much else.
The advent of the Holocene gave us the world and the possibility of agriculture as we know it.
