Norse colony and the climate catastrophe

Greenland - the terrain colonised by the Norse settlers (source)

 At a time when there is a pressing need to understand how societies respond to a changing climate, studies of past environments provide valuable insights into the relationship between past societies and climate change. Diamond (2005) identified in his five-factor framework, the complexity behind societal collapse, as explored in the last blog. A highly debated collapse story is that of the Norse colony in Greenland around 1450 A.D. and Dugmore et al., (2007) highlights that this case study provides good, scientifically-reliable evidence to explore the relationship between societies and their environment. Firstly, the Vikings kept literate records and unique historical manuscripts which provide an important historical context on the culture of the settlers at the time. Secondly, Greenland offer high quality environmental data from ice cores, soils, sediments and peat and the ability to correlate these proxies to a high standard through radiocarbon dating and tephrachronology. This blog will explore how the original thought of climate change as the main trigger behind the collapse has been evaluated in light of recent findings.

Alkenone based lake water temperature reconstruction (source)



Abrupt climatic cooling has been suggested as a key driver of the collapse of the Norse colony (D’Andrea et al., 2011). A palaeoclimate reconstruction was recently carried out by D’Andrea et al., (2011)were marine sediment cores were used to explore the alkenone saturation, a well-established proxy for sea-surface temperature (see the above graph). The study found that a major and abrupt climatic cooling at a rate of approximately 4°C per 80 years begin in 850 BP and continued until 650 BP coincided with archaeological records of settlement abandonment in Greenland. Considering that the global warming average over the last century and a half has been on average 0.85°C according to the most recent IPCC report (2014), the rate of temperature decline experienced across Greenland by the Norse was substantial. As with all palaeoenvironmental studies, limitations arise by using proxies to reconstruct the past which are crucial to considering. Prahl et al., (2003) acknowledges that factors including degradation conditions, light limitations and nutrient limitations can cause bias in the alkenone saturation data but other studies, such as Riberio et al., (2011) that used marine plankton, dinoflagellates and other palynomorph from sediment cores to infer climate variability, generated similar findings is support of D’Andrea et al., (2011). Nonetheless, the study by D’Andrea et al., (2011), provides the first quantitative temperature record for the area colonised by the Norse settlers and the study shows how quickly temperature changed in the region possibly driving the collapse. 

As noted by Diamond (2005), the indigenous Inuit society thrived during this period of climate change, proving that human survival on Greenland during this time was not impossible, hence, the collapse of the Norse colony cannot be solely driven by climate change. So why did the Norse colony fail to adapt to the changing climate? Diamond (2005) takes a different approach to that of D’Andrea et al., (2011) and Riberio et al., (2011) and is more ready blame to society itself for causing its own collapse rather. As an Iron Age society, the Norse colony was heavily dependent on wood to make charcoal and to then make iron, and this resulted in extensive, short-term soil erosion and deforestation giving rise to an Iron Age society left stripped of its abilities to make iron. Madsen (2014) progresses on the point raise by Diamond and suggests that as the climate deteriorated and supplies ran low on the island, the lack of timber to create ships used to fetch supplies and resources from the mainland, isolated the Norse colony. Another theory, which supports the fourth factors in Diamond's five-factor framework, suggests a bad relationship between the Norse and the Inuit as often the Inuit would block access to the fjords and to key source of food during critical times of the year Diamond (2005).

A conceptual model of the development of the Norse colony (source)

A more recent study by Madsen (2014)challenges this view on the Norse colony as a society which refused to adapt to the changing climate, and provides reliable evidence that the colony persisted for approximately 200 years following the onset of the climatic cooling. Instead of a sudden collapse, the society went into a gradual decline as the society attempted, but failed, to adapt to a changing climate. Madsen (2004) shows how highland and outmost farms were abandoned as a adaptive strategy to the changing climate. The centralisation of power and resources increased the disparity between the rich and the poor, and for a society who’s economy was built around natural resources, farming and man-power, the loss of farming land, the declining population and the limited natural resources was a the cascading indirect effects of climate change. Dugmore (2006)questions the timing of all these events and provides environmental records demonstrating soil erosion and environmental degradation prior to the onset of climate cooling, questioning the stability of the society before the change in the climate. This suggests that the Norse colony themselves could have initiated their collapse but was further exacerbated by climate change. 

The collapse story of the Norse colony shows how difficult it is to detangle the role of climate change and environmental change from nonclimatic factors. Recent evidence by the likes of D’Andrea et al., (2011) and Madsen (2014) provide reliable and scientifically sound evidence from palaeoenvironmental proxies which identify an abrupt climate change at a significant rate coinciding with the timing of the collapse. Dugmore (2006) argues that whether climate change is “bad” or “catastrophic”for a society depends on how the society chooses to cope with this change and will often be determined by the social attitude and social structure of the society. In the light of today’s climate change, challenges arising from global warming, triggering cascading environmental and social effects, will ultimately depend on how a society chooses to cope. Which societies will thrive and which societies will fall?