By Francesca Hutchin
Floods, famines, droughts, pandemics, soil infertility; all implicated in numerous collapses of historical societies, including of Easter Island (Brandt & Merico, 2015), Anasazi, Mayan (NASA, 2012), Harrapan, and Bronze age palatial (Diamond, 2011). Worryingly, we are facing an increase in the frequency and magnitude of extreme weather events (Carbon Brief, 2021), climate variability (Bathiany et al., 2018), food and water supply insecurity due to environmental degradation (IPCC, n.d.; UN-Water, n.d.), as well as a projected increase in frequency of pandemics (WHO, n.d.). These are all linked to the unprecedented force of anthropogenically-induced climate change (Dune, 2019; Kusunoki et al., 2020).
Societal collapse is symbolised by both significant loss of population (Butzer, 2012) and the breakdown of complexity (Bardi, n.d). It is crucial to recognise that complex societies collapse due to many different issues and preconditions interacting rather than a single factor. Preconditions of collapse include inequality, environmental degradation, and complexity (figure 1), making a society more susceptible to collapse (Butzer, 2012).
However, there is hope. Societies have faced some of these same preconditions that we now face and have survived through. This article will explore the challenges many Polynesian islands, Thule Greenlanders, and Colonial Mexico faced, how they survived, and how we can draw lessons to adapt and survive climate change and associated issues through adaptations and consideration of soil fertility and food security.
It is Important to acknowledge that as a society, due to globalisation and technological advances, we are more complex than these historical comparator societies. However, these very advances in technology and knowledge provide further tools to develop mitigation and adaptation techniques to cope with and halt climate change.
Whilst Easter Island collapsed (Diamond, 2011), many other Polynesian islands including Tahiti and Tikopia survived. Although research highlights differing environmental factors, such as higher rates of soil replenishment on Tikopia and Tahiti (de la Croix & Dottori, 2008) which contributed to their survival, it is instructive to acknowledge that the sustainability and cultural habits of Tahiti and Tikopia were significant factors enabling survival.
Tahiti survived through sustainable adaptations that allowed them to produce enough crops to feed their growing population at the same time as maintaining soil fertility; diet alterations, eating more fruits and crops grown through arboriculture, such as breadfruit (Yen, 1993), using pondfield systems amongst other irrigation systems to combat the climate variability and extreme weather events such as droughts (McGree et al., 2016); growing crops such as taro which thrive in these environments. Also, irrigation increased the fertility of field, allowing crops to be grown all year. These provided enough food for the population. Other Polynesian islands used crop rotation systems to maintain soil nutrient levels, helping to preserve soil fertility (Rolett, 2008).
Tahiti and many other Polynesian islands limited deforestation (especially slash and burn), whereas Easter Island’s slash and burn methods deforested the pine trees that covered an estimated 12.5% of its land (Brandt & Merico, 2015). This causes soil erosion, reduction of soil fertility, and decreasing crop yields (Flenley & Bahn, 2007).
Currently 200,000 acres of rainforest a day are burnt (Rain-Tree, n.d.), having huge negative impacts including soil infertility. Estimates say that, combined with forest degradation, accounts for 10%-25% of global greenhouse gas emissions (Pearson et al., 2017; Rainforest Alliance,2018). We must immediately stop deforestation in order to preserve forests, which are huge carbon sinks, and maintain land fertility by reducing nutrient-leaching and soil erosion (Sioli, 1987). We should shift our diets away from food linked to large scale land degradation and deforestation, such as cattle produced through cattle ranching, responsible for 80% of Amazon deforestation, which with cattle and other livestock industry is responsible for (estimates ranging) between 18-51% of greenhouse gases (Dopelt et al., 2019; Steinfeld et al., 2006). Foods that are often used in crop rotation, such as legumes and brassicas can contribute to nitrogen fixation of the soils, helping to restore fertility (RHS, n.d.). In doing this it is vital to provide work and support for low-income workers and communities whose livelihoods may rely on deforestation, logging and ranching unsustainably (WWF, n.d.).
To adapt to increasing food demand and increased climate variability (Folland et al., 2002) we can use appropriate techniques like Polynesians did such as crop rotation. However, irrigation techniques such as those used in Tahiti may not be appropriate as there is global depletion of groundwater sources (Wada et al., 2010) and many areas have increasing water insecurity (Boretti & Rosa, 2019). Using methods such as drip-irrigation would be more appropriate in order to conserve water.
In addition, the collapse of Easter Island is linked to smallpox epidemics brought to the island by European colonisers (Brandt & Merico, 2015). With climate change the frequency of pandemics is forecasted to increase (Harvard., 2020) and, although COVID-19 is unlikely to trigger societal collapse (Wade, 2020), we should learn lessons such as providing more resources and funding for research to prevent and prepare for pandemics, enforcing global protocols where scientifically appropriate, and ensuring accessibility to vaccines and equipment for everyone. This is essential to reduce the risks of/from future pandemics and prevent economic recession and population depletion.
During the Colonial period in Mexico, 1701-1821, it experienced an increase in weather variability as well as in ‘extreme’ climate events such as droughts, floods, and hurricanes (Endfield et al., 2004). Similarly, climate-linked ‘disasters’ have increased in frequency by over 83% between 2000-2019 and the previous 20 years (UN, 2020a).
In the face of much uncertainty and a tumultuous climate agricultural systems were implemented to help maintain water and food security, enabling the society to survive. These included mixed farming, where farmers collected and sowed seeds from their own crops (Badstue et al., 2006), as well as Government-sponsored grain stores (Reales alhóndigas) (Gliessman, 1989) to store grains to help cover food requirements in the future such as in times of Drought. Mixed farming also involves diversifying the food produced on a farm in order to help to reduce dependency on one crop and increase the productivity of the land (Monzote, 2008). These practices, in combination with irrigation using groundwater from aquifers (Mendoza et al.,2005) helped to feed the population, enabling survival.
We must also take action to ensure food security through mixed farming methods, using crop rotations, nitrogen- fixing crops (such as legumes), as well leaving land fallow on rotation (Endfield & O’Hara, 1999) to maintain soil fertility. In addition, growing crops that are suitable for the increase in extreme weather events, such as foxtail millet and rice in areas that are more prone to drought (Kebede, 2019) and floods (UC Riverside, 2019) respectively. Scientists are also using genetic engineering to create strains of crops that are more resistant to extreme weather events (Ro, n.d.).
There were spatial patterns though. Those who had a lot of land and resources could afford adaptations such as irrigation and mixed farming, buffering the effects of the numerous droughts of this period, whereas many indigenous communities, the poorest and oldest in society, could not and suffered the full brunt, leading to many deaths due to famine and starvation (Endfield & Tejedo, 2006). Also, many colonisers used Government-sponsored grain stores (Reales alhondigas) to profiteer, leaving many indigenous people unable to afford it.
Inequality in our current society has enabled and enhanced many of the preconditions we face today. The richest 1% responsible for 15% of C02 emissions, over double the emissions of the poorest 50% of the world population (Oxfam, 2020). The excessive consumerism and wealth of the rich is the driving force of many preconditions (figure 1) (such as deforestation, anthropogenically- induced climate change, inequality) as it creates an unsustainable demand which stretches Earth’s ecological carrying capacity, and products and resources are then also distributed unfairly. This over-stretching of resources has been involved in the collapse of all complex societies in the past 5,000 years (Motesharrei et al., 2014). To tackle climate change and climate-related events means tackling inequality and ensuring food security for all worldwide.
The Little Ice Age was a climate interval characterised by falling temperatures, the advancing of glaciers and ice. Records suggest average winter temperatures in Europe and North America were as much as 2 Celsius lower than today (Oosthoek, 2015). During this period both Thule Inuit’s and Norse Greenlanders resided in Greenland (Folger, 2017). Adaptations and different lifestyles allowed Thule people to survive, whereas the Norse Greenlanders died out. The Norse Greenlanders continued to focus on methods of food production, building and lifestyles that they had previously used in mainland Scandinavia, with heavy reliance on livestock and using the scarce, precious resources (like timber) and soil to build many churches (Diamond, 2011). The over-reliance on livestock was unsustainable. The falling temperatures of the Age meant it was often too cold for animals to survive and crops which were harder to grow had to be used to feed them (Dugmore et al., 2007). This exacerbated the problems of food insecurity and eventual famine that the Norse Greenlanders faced. They failed to learn from the Thule, whose diets focussed on hunting animals like ringed seals, caribou, and whales as well as fish (Grønnow et al., 2011). This was more suitable for the climate, and their nomadic lifestyle allowed them to move around to wherever food was most plentiful.
However, despite their eventual collapse, the Norse Greenlanders did manage to survive some 500 years due to some adaptations (Dugmore et al., 2007). They did increase hunting but over- relied on certain ones and over-used rare materials like timber and ivory (Dugmore et al., 2012).
From these examples we can learn to adapt our diets and growing patterns to suit the changing climates of our world. For example, Northern Europe is forecasted to have a longer growing season due to rising temperatures (Peltonen-Sainio, n.d.) and is now able to grow crops such as grapes and olives which are traditionally grown further south (Olesen et al., 2011). However, there is also huge, predicted population growth (Kasotia, 2020), particularly in Africa and Asia where crop yields are also predicted to fall (Andrews, 2014; Aryal et al., 2020).
We must listen to the science regarding sustainable adaptation and mitigation methods for the changing climate (Milman & Smith, 2019), and can learn from indigenous people who have a wealth of knowledge about their environments. Avoiding over-reliance on particular resources, crops or energy sources, and a shift to green renewable energy are imperative but we must reduce carbon emissions immediately in order to keep global warming to 1.5 (IPCC, 2018). To date there is still no largescale transition to these underway, and it will be hard to meet the extremely high demands (Barnosky et al., 2016) so it is clear we must not be over-dependent on resources, and should ensure diverse research, development, and introduction of a wide array of renewable energy sources and adaptation techniques.
COVID-19 makes now the ideal turning point for society as governments globally are pouring billions into economic recovery. It is imperative that these economies are rebuilt in a sustainable and eco-friendly way. COP26 is an amazing opportunity for the world to enact international action with accountability, as opposed to agreements that fail to translate into large- scale climate action (UN, 2020b).
If we act immediately and holistically the World can still meet the needs of the growing population, as well as reducing global poverty, and developing sustainably (IPCC, 2018). Forecasts of 200 million environmental refugees by 2050 (IPCC, 2008) would place more pressure on the carrying-capacity of habitable areas. The time to act is Now. There is no time to lose and a World to preserve.
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 Arboriculture is the “cultivation of trees and shrubs”(Oxford dictionary, n.d.)
 A pondfield systems is a system where the water is redirected from a stream to an artificially terraced field, it then flows between adjacent flooded fields (Farrington & Bellwood, 1980; Galipaud & Piazza, 2006)
 Celsius above pre-industrial levels (IPCC,2018)