Subboreal

The Subboreal is a climatic period, immediately before the present one, of the Holocene. It lasted from 3710 to 450 BCE. The composite scientific term Subboreal, meaning "below the Boreal," is derived from the Latin sub (below, under) and the Greek Βορέας, from Boreas, the god of the North Wind. The word was first introduced in 1889 by Rutger Sernander to distinguish it from Axel Blytt's Boreal, which had been established in 1876. The Subboreal followed the Atlantic and was 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, it is divided into an Older Subboreal and a Younger Subboreal. Historically, the Subboreal is equivalent to most of the Eneolithic and the entire Bronze Age, which started 4200 to 3800 years ago. The Subboreal is usually defined as 5660 to 3710 years BP. The lower limit is flexible, as some authors prefer to use 4400 BCE, or 6350 BP in northwestern Poland, even 4830 BC, or 6780 BP, And 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 1170 to 830 BCE, but it is usually fixed at 450 BCE. In varve years, the Subboreal corresponds to 5660 to 2750 years BP. The boundary between the older and the younger Subboreal is considered to be 1350 BCE. The climate was generally drier and slightly cooler (by about 0.1 °C) than in the preceding Atlantic but still warmer than today. The temperatures were 0.7 °C higher than during the following Subatlantic. Consequently, in Scandinavia the lower limit of glaciers was 100 to 200 m higher than during the Subatlantic. On the whole, the oscillating temperatures slightly receded in the course of the Subboreal by about 0.3 °C. In the Aegean, the beginning of the Subboreal was marked by a pronounced drought, centered around 5600 years BP.