Regional History of Settlement and Human Impacts in the Baltic Sea Region Over the Last 2000 Years
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Climate Science. Please check back later for the full article.
The Baltic Sea water catchment area reaches from the upper course of River Elbe in the Czech Republic to the northernmost Lapland where River Tornionjoki (Sw. Torneälven) is the border between Finland and Sweden today. Because the area is very large, the current discussion concentrates mainly on coastal regions of the sea.
In this area, climatologic information is based on polar ice drilling data from Greenland and Holocene tree-ring data. In addition, AMS (Accelerating Mass Spectrometry) the dates of archaeological material are used for building detailed chronological sequences.
Between ca. 200 BCE–100 CE the climate was relatively warm. Archaeologically, the period is the Early Iron Age when local iron production expanded in the Baltic Sea region and allowed effective slash-and-burn crop cultivation here for the first time in prehistory. The influence of climate changes on human subsistence is well visible in pollen data from ponds and swamps that are numerous in the Baltic Sea coastal zone.
That period was followed by a cold phase in 100–600 CE. In areas where man exploits nature in harsh climate conditions, slight changes in annual temperature have great impact on subsistence. An abrupt and radical fall of temperature surely causes severe difficulties. A climate catastrophe, probably caused by volcanic eruption, tortured both urban, peasant, nomadic and hunting populations all over the northern hemisphere in the year 536 CE. Recent archaeological studies and AMS samples have proven that a demographic crisis exists in the northern part of the Baltic Sea.
Soon after 600 CE, the climate got milder again, and the following centuries were warmer than hardly any period before or during the Holocene. In the Baltic Sea region, the warm phase from 800 to ca. 1050 CE perfectly matches a historical and archaeological era: the Viking Period. The arable land was already considerable in the southern part of the Baltic Sea during the early Iron Age. Human activity caused the disappearance of the forest and the change of the environment around the Baltic Sea.
Hunter-gatherers would find secondary food resources when primary ones were not available. But societies that were strongly dependent on one single base for economy, such as agriculture, had great difficulties. According to Finnish research, the so-called Little Ice Ace took place between 1695 and 1911 CE.
Since the beginning of industrialization in the mid-19th century, human impact on climate is obvious all over the globe, and the Baltic Sea region is no exception.