Ten years ago I read a review of a book, which I just had to have, and I bought it. It was by Steven Mithen (After the Ice: a global human history, 20,000-5000 BC), and I read it from cover to cover, greedily. It told the story of the development of humanity from 20,000 years ago, and used prehistoric and anthropological evidence in an imaginative and attractive way. I had wondered for years whether or not there had been an earlier human civilisation between earlier ice ages. Mithen thinks not, and he is joined by all the experts I have talked with. What you see in our present civilisation is the result of the work of several hundred generations of human beings. What we have done — our species — has no counterpart in the history of the planet.
Then, a month ago, I read a long article on Watts Up With That by Andy May, a physicist interested in rocks, on the same subject, and he relied on and acknowledged his debt to the same book. To better explain his own argument May created a giant chart. It is packed with information, drawn from good sources, and it looks like this:
No, I agree that you can’t read the text. To do that you’ll have to go the article at the link above, and it is very well worth doing — that is, if this sort of thing interests you. But some of what is there will be clear as I try to summarise what is a very big picture indeed. The timelines move from the left to the right, and the three long lines in the upper half are temperatures in Greenland and Antarctica over the last twenty thousand years, based on ice-cores. You can see that the last ten thousand years they have been steady, with small fluctuations above and below the mean.
One of May’s continuing themes is that, for all life, cold is bad and warm is good. Civilisations collapse when there is prevailing cold, which tends to bring with it drought. Warm times tend to be wet times, and plants flourish. So too do we humans. The last glacial period can’t have been very enjoyable, and humanity cannot have been a dominant life form. But something happened around 13,000 years ago, with the beginnings of urban life, cut short very quickly by what is called ‘the Younger Dryas’, a return to glacial cold that lasted for a thousand years.
When it ended there was a further burst of agriculture and urban development, with domesticated animals and large-scale farming. The modern city of Jericho seems to have occupied a site of urban life for 11,600 years. The Sahara became savannah-like. Around 8000 years ago there was another long-term cold snap, which returned the Sahara to desert-like conditions, and ended many settlements, with survivors moving to permanently flowing rivers, like the Nile. From then on we have quite a lot of archaeological evidence, and then from five thousand years ago, we have written or engraved evidence.
The warm and cold periods in the last ten thousand years can be determined quite accurately through ice-core data, and they accord with what we know of the rise and fall of human civilisations. All of this was in a sense known to me because I was trained in history, though I knew nothing of the ice-core evidence. But human history is my intellectual base, and I have known for a long time that the decline and fall of the Roman Empire was associated with a change in climate, with cold in the North of Europe pushing more and more tribal groups south, where crops could still be grown. That put enormous pressure on the Roman frontiers, and they simply gave way.
The return of human urban civilisation from the ‘Dark Ages’ to the Renaissance from which we date modern civilisation, is likewise associated with the return of warmth to Europe. We know about the Little Ice Age (which was not a consistently cold period, but a generally cooler one with some notably frozen short episodes) because there is abundant literary, historical and pictorial evidence of it.
I accept that natural scientists might not have learned any of this in their own education. But that all this could simply have been ignored, when the IPCC began to look at global warming, almost passes belief. While I have given May’s long essay scant treatment here, it is really worth a good read, and the chart is a great piece of work.
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Thanks. A fascinating chart. Most interesting.
Thanks Don I has just gone to OfficeWorks to get a large copy. My own A3 printer is not large enough.
Our species is about 400000 years old and that means it has survived about 3 ice ages (Vostok ice core). How I can not imagine but it is the reality. The interglacials were all warmer than our current one. I agree totally with the idea that life for humans is much better when is warmer. If the climate truly can be controlled let us raise the temperature at least 2°. Inevitably the current interglacial will end and the next ice age will start. I am optimistic that the human race will cope but for sure none of us have to worry about it.
I also thank you for referencing the book.
I found this to be an interesting and balanced piece until your penultimate sentence
when you wrote
“But that all this could simply have been ignored, when the IPCC began to look at global warming, almost passes belief.”
Do you really think the IPCC simply ignored all “this”? In my view, you could have
considered something writing something just a little more measured.
And if you were feeling particularly energetic it would be helpful if you could outline what, if any conclusions, we should draw from this analysis. Another post perhaps.
Nothing of any consequence on this subject can be found in the WG1 sections of either AR4 or AR5. You will find occasional references when the orthodox case is being supported by historical evidence, but not when the historical evidence is counter to it. The most obvious example is Mann’s hockey stick in AR3, which was given front-page treatment, though it flew counter to almost everything that was known through historic evidence.
So, this is what you should write. Its far more informative than what you originally wrote.
I wonder what your message is?
If you look at top data series you can see a gentle decrease in temperature over 8000 years until about 1860. Just about every increase was matched by a decrease. But after 1860 it is the only time in the whole data series that you get 4 temperature increases in a row. It looks quite different!
The author you provide a link to suggests that there be bi-directional link between CO2 and temperature. That might be true in general. Over the eons there are obviously mechanisms which enable the earth’s temperature to return to the mean. We can all see the cycles in the ice ages. But obviously in this case, the AGW hypothesis is that humans releasing CO2. So claims of bi-directional causality are spurious. The change in CO2 is exogenous, obviously!
And these arguments about whether humans do better in cold or warmth miss the point. I could simply argue that Western civilisation developed in the cold climates of Europe and North America, not the equator. It is the sudden change in temperature which is the concern. So if CO2 caused rapid cooling that would also be an issue.
You must be looking at a different graph to me. There are a few jumps similar to what we are seeing now. The declines happen after the jumps, and in 10,000 years, 100 are not statistically large. Plenty of time for declines. I believe that CO2 must make a difference, but it is hard to see where it’s effect can be differentiated from background noise at the moment.
1860 to 2000
There’s similar periods of temperature rise elsewhere in the record, so what’s your differentiating factor?
A corresponding rise in CO2
Lets be honest, the science is overwhelming. When you dig a little deeper with sceptics they concede they just don’t care.
Your statement that ‘the science is overwhelming’ is so vague as to be meaningless. What in particular do you regard as the overwhelming papers or data or arguments that tell you … what?
When you can tell me that, we might be able to agree or disagree about something in particular, as Popper would agree.
In absentia David would like to remind Don that:
“The growth of knowledge depends entirely on disagreement” Karl Popper
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