Subboreal
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Holocene Epoch |
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 Oak-hornbeam forest at Žernov, Czech Republic. |
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The Subboreal is the second before last climatic period of the Holocene. It lasted from 3710 to 450 BCE.
The composite scientific term Subboreal, i. e. below the Boreal, is derived from the Latin sub (below, under) and the Greek Βορέας - Boreas, the God of the North Wind. It was first introduced in 1889 by Rutger Sernander to distinguish it from Axel Blytt's Boreal, established in 1876. The Subboreal replaces the Atlantic and is followed by the Subatlantic.
The Subboreal is equivalent to W. H. Zagwijn's pollen zones IVa and IVb and T. Litt's pollen zone VIII. In the pollen scheme of Fritz Theodor Overbeck it occupies pollen zone X.
In paleoclimatology the Subboreal is divided into an Older Subboreal and a Younger Subboreal. Historically the Subboreal is equivalent to most of the Neolithic and the entire Bronze Age which started 4200 to 3800 years ago.
The beginning of the Subboreal is usually defined as 3710 years BCE or 5660 years BP. This lower limit is flexible, as some authors prefer to use 4400 BCE or 6350 BP or like in northwestern Poland even 4830 BC or 6780 BP, whereas others use 5000 calendar years or 3050 BCE. The upper limit of the Subboreal (and therefore the beginning of the Subatlantic) is also flexible and can be attributed to the interval 1170 to 830 BCE, but is usually fixed at 450 BCE. In varve years the Subboreal corrsponds to the interval 5660 till 2750 years BP.
The boundary between the older and the younger Subboreal is equated as 1350 BCE.
During the subboreal the climate was generally dryer and slightly cooler (by about 0.1 °C) than in the preceding Atlantic, but still was warmer than today. The temperatures were 0.7 °C higher than during the following Subatlantic. Consequently, in Scandinavia the lower limit of the glaciers was a 100 to 200 metres higher than during the Subatlantic. On the whole the oscillating temperatures slightly receded in the course of the Subboreal by about 0.3 °C.
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