Abrupt Holocene climate change as an important factor for human migration in West Greenland

Temperature fluctuations in West Greenland are known to have impacted human movement and migration during the Holocene period. However, due to the myriad of social, political, and economic reasons that humans move from land it is difficult to pinpoint how much temperature impacted change in behavior. D’Andrea, Huang, Fritz, and Anderson et al. (2011) tested the relationship between temperature and four groups that inhabited West Greenland during the Holocene period through the comparative study of sediment samples from two lakes. This method allowed researchers to compare the past state of temperature variability in West Greenland with historical records of human populations in the region. The study found that fluctuations in temperature did have a positive correlation with population shifts out of the West Greenland area. Importantly, this research helps provide examples of how climate change has shaped geological epochs of human history.  – Adriane Holter
          D’Andrea, William J., Huang, Yungsong, Fritz, Sherilyn C., Anderson, John N., 2011. Abrupt Holocene climate change as an important factor for human migration in West Greenland. Proceedings of the National Academy of Sciences of the United States of America, 108: 9765-9769.

          During the Holocene period, four groups of people lived in the West Greenland area: the Saqqaq (4,500 y B.P.), the Dorset (2,800-2,200 y B.P.), the Norse (650 y B.P.), and the Thule who still remain in the area to present. Throughout the Holocene period, the civilization of these four groups was substantially impacted by temperature change. For instance, access to resources and tools for acquiring such resources was greatly influenced by environmental conditions. Thus, an abrupt change in temperature had the potential to alter the lives of a population to a large enough degree that they left an area. When compared to human migration in West Greenland, it is highly likely that Holocene temperature variability was a dominant force in population shifts.
          During the time that the Saqqaq inhabited West Greenland, the region experienced an interval of warmth that then shifted into a transient period of warmth and cooling between the years 4,100 and 3,400 B.P. The authors hypothesize that an abrupt cooling of the region that occurred in 3,400 B.P. began to push the Saqqaq out of the Sisimiut region; however, it was not until further decrease in temperature in 2,800 B.P. that the group left the area completely. Thus, the magnitude of the temperature shift is an essential element of how humans experience climate change; rate of change alone does not determine human impact.
          Unlike the Saqqaq, archaeological evidence from the Dorset population suggests that the group was better adapted to handle fluctuations in temperature. For instance, remnants of tools for sea-ice hunting suggest that the Dorset were well suited to cold weather conditions. Due to their living strategies, it is more difficult to determine why the Dorset abandoned the region in 2,200 B.P instead of other periods of significant temperature change that occurred during the time they inhabited West Greenland. The unclear reasons for the migration of the Dorset remind us that theories of climate change produce only a partial explanation of human movement. Nevertheless, temperature shifts can partially explain why certain groups move into an area to begin with. The warming of West Greenland experienced from ca. 1,000 to 850 B.P. (roughly middle of the 14thcentury) is one probable reason that the Norse migrated to the region. Once again, lifestyle factors impacted how a population was impacted by climate change. A sedentary farming population, the Norse were less able to response to temperature shifts and were therefore greatly impacted by the period of increased cooling from 850 until 630 B.P. when they abandoned West Greenland leaving the area free for the Thule to settle to the present day.
          In order to establish these relationships between temperature and population in West Greenland, the researchers studied sediment cores from two lakes (Braya Sø and Lake E) that were 10 kilometers apart. By examining the alkonene levels in the sediment cores, the authors were able to reconstruct sea-level temperatures during thousands of years. This research was strengthened by the fact that previous studies have shown air temperature has a strong impact on sea-level temperature in West Greenland. The study indicates that temperature might have varied as much as 5.5 ° Celsius in the Kangerlussuaq region over the past 5,600 years. Interestingly, the authors found that the temperature patterns in West Greenland were anti-correlated with other areas in the North Atlantic such as southwest Ireland. 

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