Climate change and archaeology
Very interesting post by Mike Haseler in Brit Arch:
Essentially he is saying that methods of recording the past tend to attentuate temperature change, smoothing down the peaks, so a comparison of present (measured with modern instruments) compared with the past will tend to so wilder fluctuations now than then just because of methods of recording.
The post is as follows (with thanks to Mike for permission to quote it):
'Having studied the recent instrumentational record of global climate, half the change takes place in periods less than 10years and half over ten years. So it seems pretty clear that unless multi-proxy temperature reconstructions have an accuracy of better than 10years there will be a substantial reduction in the apparent variability of global temperature. To put that simply, there are many peaks/troughs that are 10, 30, 100 years long. If two proxies are offset by e.g. 10 years, the peak in one proxy will not coincide with that in another and therefore the size of the 10year peaks/troughs will be substantial reduced, however since 20 years of the 30 year peaks still coincide they will still show strongly. Similarly if the proxies are offset by 30, or 100 years, the effect is to reduce the apparent variability of peaks/troughs of these durations.
So, even if you have very sensitive proxies, if they aren't also extremely accurate in their dating, the apparent variability of historic climate will be significantly reduced, with the effect that if you compare a reconstruction of the historical global temperature using proxies with an instrumentational record (which all obviously have accurate dating) it will appear that modern temperature changes are far more dramatic than historic temperature changes.
In short, I'm really would like to find a way to reconcile the archaeological narrative of climate being a dramatic influence on human culture, with the modern "global warming" narrative of "unprecedented climate change" which appears to have had negligible effect on humans.
To put it bluntly, in the light of the current accepted narrative of a stable world climate and unless there is a way reconcile the archaeology and temperature reconstruction, any archaeologists talking of any change because of this or that warmer or cooler period (whether world or regional unless backed up with clear temperature records) is really opening themselves us to a charge of being a "fraud".
Have archaeologists been over-egging the effects of climate?'
Essentially he is saying that methods of recording the past tend to attentuate temperature change, smoothing down the peaks, so a comparison of present (measured with modern instruments) compared with the past will tend to so wilder fluctuations now than then just because of methods of recording.
The post is as follows (with thanks to Mike for permission to quote it):
'Having studied the recent instrumentational record of global climate, half the change takes place in periods less than 10years and half over ten years. So it seems pretty clear that unless multi-proxy temperature reconstructions have an accuracy of better than 10years there will be a substantial reduction in the apparent variability of global temperature. To put that simply, there are many peaks/troughs that are 10, 30, 100 years long. If two proxies are offset by e.g. 10 years, the peak in one proxy will not coincide with that in another and therefore the size of the 10year peaks/troughs will be substantial reduced, however since 20 years of the 30 year peaks still coincide they will still show strongly. Similarly if the proxies are offset by 30, or 100 years, the effect is to reduce the apparent variability of peaks/troughs of these durations.
So, even if you have very sensitive proxies, if they aren't also extremely accurate in their dating, the apparent variability of historic climate will be significantly reduced, with the effect that if you compare a reconstruction of the historical global temperature using proxies with an instrumentational record (which all obviously have accurate dating) it will appear that modern temperature changes are far more dramatic than historic temperature changes.
In short, I'm really would like to find a way to reconcile the archaeological narrative of climate being a dramatic influence on human culture, with the modern "global warming" narrative of "unprecedented climate change" which appears to have had negligible effect on humans.
To put it bluntly, in the light of the current accepted narrative of a stable world climate and unless there is a way reconcile the archaeology and temperature reconstruction, any archaeologists talking of any change because of this or that warmer or cooler period (whether world or regional unless backed up with clear temperature records) is really opening themselves us to a charge of being a "fraud".
Have archaeologists been over-egging the effects of climate?'
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