Should the Mayans be blamed for their own tragedy?

While doing my last blog I wondered…if we are now facing the consequences of exploiting our own natural resources, then could the Mayans also have contributed to the worsening of their own drying throughout the classic-postclassic period.

A recent paper by Medina-Elizalde and Rohling (2012) highlighted the fact that the ecological carrying capacity of the Yucatan Peninsula is highly sensitive to precipitation reductions. They found reductions in the frequency and intensity of cyclones over the Yucatan Peninsula which coincided with the collapse of the empire. They estimated this reduction is up to 40% mostly during the summer season. Did human influences on land cover intensify the drought condition?

Figure 1: Source Cook et al (2012) 

Figure 2: Source Cook et al (2012) 

Cook et al (2012) suggest deforestation by the Mayans had indeed influenced their climatic system to a drier mean state. Using a “new suite of climate model” they found a few interesting results:

Precipitation level

There result suggested an annual 5%-15% decrease in precipitation due to deforestation, located in regions with the most land cover change in Southern Mexico and Yucatan peninsula as shown in Fig.1 and Fig 2a. As Fig2b the reduction in precipitation is largely driven by 10%-20% reduction.

This modelling differed to Medina-Elizalde and Rohling (2012), hence it shows the constraints between using peloclimatic data and modelling. But both agreed that deforestation increases dryness.  

Figure 3: Source Cook et al (2012) 

Figure 4: Source Cook et al (2012) 

Driver of Drought

Modelling conducted here differed to Oglesby et al (2010) which found that drought was accelerated by thermal mountain effect. Cook et al (2012) paper showed that it was due to the reduction in available energy. From fig 3 we can see that the net radiation at the surface decreases. This can be explained by a shift from dense forest to domestic crops, which led to increases in the surface albedo.  Fig 3b also shows decline in laten heat, also due to the increased area of crops which has shallower roots and lower leaf area. Given the above factors, this would lead to a reduction of shallow convective cloud cover as shown in Fig 4a, and in turn lower levels of precipitation.  Fig 4b and 4c showed that deforestation leads to an increase in cloud top temperature. This would suggest a lower elevation of cloud tops and a reduction in cloud water content. They all point towards a lower convective activity which is consistent which fig 2b that shown a decreased in precipitation level  

Implication of results

Since the deforestation scenario uses peak population and deforestation level, it can be used as an analogue for the conditions during the 800-950CE. This provides an insight into the fact that the growth of the Mayans acted as a ‘double edged sword’. The extent of deforestation, and given the Yucatan peninsula has a high sensitive to precipitation change, they exemplified the drought that occurred. They estimated that deforestation contributed to between 12.5% - 60% of total drying. Coupled with the fact that the modelling showed the location of severe drought coincided with regional centers of the Terminal and Postclassic period, it further reinforeces the causality between climate change and political stability, demographic decreases and cultural change.  It is important to note that the stimulation does not answer the question of why the Southern Mayan lowlands collapsed before the more arid northern Yucatan.

The other side of the story

McNeill (2012) showed a host of sustainable engineering and policy that were implemented across Mesoamerica during the Classic period. This discussion extents Cook et al (2012) quantitative modelling and give more depth into our discussion.  Below are some of the examples:

The management of forest

a.     The elite certainly contributed: This is in the interest of the elite to maintain forests because it produces symbols of elitism, like deer and caco meat, valuable woods, jaguar pelts and bird feathers.

b.     A source of construction. In the city of Tikal, during the class Maya they used to use Manikara zapota (M.Z) woods which grow in moist tropic forest. Research showed they use freshly cuts woods instead of old trees (Lentz and Hockaday 2009) in AD766 the builders of Tika used a different tree called Haematoxylon campechianum L.  For 40 years they allowed for the M.Z trees to recovery before using it again as a construction material

c.     In the late classics, tropical forest were close to the city and there were evidence of the preservation of historic tress (Harrison 1999)

Farming Techniques

a.     Use of ridged fields, although not common, helps aerate the soil, concentrate topsoil and focus greater amounts of moisture around plants. One such example is the 6^th Century AD site of Ceren in El Salvador.

b.     Terraces were found across Lowland Mayan area (Wyatt 2008). With the aim of retaining, preserving and catching runoff soil. But Dunning (1996) noted not all places uses this technology, as in the case of Puuc Maya in the Yucatan Peninsula, despite being located in a hilly terrain.

McNeil (2012) rejects the idea that the Mayans of the late classic period should be blamed for the environmental devastation that was observed during that period. Instead, he champions the idea that the Mayans in the classic period learnt from their ancestors in the pre-classic era which caused environmental damages across Maya lowland through swidden agriculture. Out of necessity, the Mayans developed the above sustainable techniques to increase the efficiency of agriculture in order to satisfy demand.  At the end of the Classic period, some areas like Copan actually experienced an increased in forest cover (McNeil 2012).

Conclusion

There are inherent problems with modelling. The fact that the model Cook et al (2012) used could not incorporate spatial patterns of land cover change at a higher resolution and that uncertainties exist with the estimation of land cover changes could underestimate the effectiveness of the Mayan's sustainable technique and policy. However, not all places were implemented with these techniques and uncertainty lies within the extent that these sustainable techniques could increase agricultural output without deforesting more land. I believe that deforestation is inevitable and deforestation as Cook et al (2012) showed certainly have contributed to drier climates during between 800-950CE. However, uncertainty lies within earlier dates - within early and mid-classic period - where population growth/density were lower. This could imply sustainable agricultural technology could produce enough food without the need for Mayans to cause mass deforestation. In turn, the drying effect from deforestation should be much lower during the early/mid-classic period.  Nevertheless, the Mayans should take partial responsibility for exploiting nature. 

Analogy to modern society 

It is important to note Cook et al's is significant in the sense that if climatic change undermines our agricultural system in areas like Africa or Europe it could lead to wide spread social disorder or even war. Given we live in an age of globalization this will draw in others. Also, the paper highlights the dangers of deforestation and the 'knock on effects' it has in the climate system. McNeil's paper is equally important and it suggest to us that even though the Mayans are aware of the consequences of deforestation, and have ways of mitigating the effect through better technology, but they still fail to solve the inherent problem of sharing resources with too many people - especially when resources where decreasing due to climate change. This is an important lesson as our modern society should wake up, and not get dragged down by global institutions on climate reform and scapegoating the poor nations (see my last post here). We should start reforms within developing and rich nations TODAY. 

“Typhoon Haiyan; Worse than hell”

Last week a Filipino diplomat gave a passionate speech in Warsaw during the climate change conference. He linked the disaster to man-made climate change and "urged the world to wake up". 

The economist (2013) called it “one of the strongest storms ever recorded” and commented that the Filipino government are insisting that man-made climate change is heightening the risk of typhoon.  Also, David Cameron had acknowledged the fact that climate change may have influenced the ‘increasing’ number of extreme weather (Guardian 2013). I want to explore the above statements and question whether disaster like Haiyan would become more common, and with it social disorder.

Fig 1: Projected surface temperature changes for early and late 21^st century relative to the period 1980-1999 (source; IPCC fourth assessment report: Climate change2007) 

figure 2 source  Race et al (2010) 

Figure 3a and 3b source Webster et al(2005) 

The association between climate change and increase in hurricane activity is complex in nature. It is well known that SST (Sea Surface Temperature) >26 degree is required for the formation of tropic cyclones. The IPCC 2007 report has shown that temperature would increase under all the scenarios and especially that of SST (fig1).  Would that point to higher frequencies of hurricane formations? 

A study conducted by Race et al (2010) has shown that there is a high correlation (up to 0.7 for some points) between SST and storm counts in the month of August off the coast of West Africa. However, this is specific in nature and could not be generalized for all ocean basin. Webster et al(2005) noted that there are possible influence of interannual variability associated with El Nino and the North Atlantic Oscillation which make it hard to draw relation between future increase SST and frequency of hurricane.

Figure 3 showed statistically there is no correlation between increase in the number of Storm days (or number of storm) in relation to the increasing level SST in all ocean Basin. On the other hand, there is substantial decadal-scale oscillation that is especially evident in the number of tropical cyclone days. For example, it peaked at 970 days around 1995 and decreased by 25% to 600 days in 2003.

Figure 3c source Webster et al(2005) 

Figure 4 source Webster et al(2005) 

Figure 3c also showed there is no statistically significant trend linking increasing SST and number of hurricane and displays the same trend as figure 3a/b. The exception is data for the North Atlantic (NATL), which also corresponds to the data found by Race et al (2010), where there is a statistically significant increase in hurricane starting from 1995 in relation to the increased levels of SST.

However, without any comparable correlation in other ocean basin where SST is increasing it means we cannot simply associated the number of storms to a warming SST environment. The ‘coincidence’ in the North Atlantic region, coupled with statistically positive results has fuelled speculation this was the result of climate change via higher SST

More importantly, Webster et al(2005) observed an increase in hurricane intensity between the same periods. As shown in figure 4, strongest categories (4 and 5) have nearly doubled in numbers, occurring in all ocean basins. Emanuel (2005)'s model might provide a insight into the future intensity of hurricanes. His model suggests that an increase of 2 degrees in tropic SST would increase wind speed by 10% and power dissipation by 40-50%. 

Webster et al(2005)'s paper indicates that in the last 30 years, there has been a trend towards more intense hurricanes and they seem to be right. Their observation is consistent with that of Knston et al 2010 (Using a CMIP3 generation model).Their climate model with scenario A1B from IPCC 2007 (for late twenty-first century) predicts there will be an increase in intensity of tropical cyclones of around 2-11% by 2100, and the frequencies of these types of cyclones would increase as well. On the other hand, the general frequency of tropical cyclones would decrease by 6-34%. 

Figure 5 source Emanuel 2013

Figure 6 source  Emanuel 2013

The latest finding from Emanuel (2013) (using a CMIP5-generation global climate model) complicates the picture between climate change, frequency and intensity. One of the main point is that it shows the global frequency of downscaled tropical cyclones will increase throughout the century by around 10-40%, contrary to the results from Knston et al (2010) (not saying they are wrong). The location of the increases in frequencies of tropical cyclones is also shown in fig.5, concentrating in the North Pacific, coincidentally, in the same region as Typhoon Haiyan. At the same time, the increases in the intensity measure by power dissipation index is consistent with the increase in track density (fig 5), concentrating in the North Pacific region. Power dissipation at landfall will increase by around 55% over this century.

The above have shown climate change wasn't the cause of typhoon Haiyan. Evidence suggests climate change up to this point had no/little influence over the frequencies of cyclone formation or to some extent its intensity. Instead, Typhoon Haiyan should be a wakeup call to the vulnerability across the global, especially those near the coastline. The North Pacific region is of concern since the increases in intensity of smaller cyclones are concentrated in that region, whilst frequencies of these small typhoons are also on a upward trend. It also exposes the complex nature of modelling future cyclone behaviour, where results will differ depending on the type of model used, which adds uncertainty to the discourse.

 More importantly, the physicality of the hurricane is only one of the main factors that increases the vulnerability of population. A host of factors from climate change (sea level etc) and human factors (preparedness or GDP ppp etc) also determines the level of social disorder. Hence, I am just showing you one side of the story and the future behaviour of hurricanes should be of concern!  

Volcano as solution!

Following from last week, as I haven’t mention the causes of the little ice age.  I will talk abit about that. Studies by Geoffrey Parker and Bridda, Schweingruber and Osborn have shown that It is predominately linked to the Huaynaputina eruption in Peru (1601) which drastically cool down the earth as Parker had illustrated in the below chart. Showing correlation between the eruption and temperature drop. Additionally,  Bridda, Schweingruber and Osborn proved that the extend of the effects of the ash cloud was previously underestimated and shown by tree ring density and ice core records from Greenland and Antarctica (For more detail refer to there paper on page 452 bottle right).

This gave me an interesting and idea of using ‘ash’ to mitigate the effect of climate change and hence the social and economic instability brought forward for its effect. It turns out a radical thinker called David Keith has brought about this idea already. The below is a link which talks in more detail about his idea.

This would be quite interesting since, the little ice age was brought forward in parts by the largest eruption in the last 600 years. Therefore, if we could use ash clouds to cancel out the effects of future temperature increase, this would buy humanity some more time for more concrete and long term solution.  Potentially delaying the future rise of social disorder that would be accompanied by changes to our climate (to which I will explore on later in this blog,  such as the risk of war etc, because I don’t want to give it away).

The next entry will return back to the idea of scapegoating in the present.

Enjoy the video and until next time. 

Witches; effects of climate on society

To start off ‘Little Ice Age’ refers to the time AD 1570-1730 and in early 19^th century. And unusually warm conditions have followed since the 1920s. This entry will talk specifically about the period between 16^th - 18^th centuries Europe.

Well…to some my title may seem ridiculous, but if a peasant during that period saw this blog they would completely agree with me. Why is this the case? And how would witches be linked to Climate change?

I think its associating goes beyond that suggested in dictionaries like the one below: 

  

I believe this word exposes something greater. It exposes the vulnerability and susceptibility of one’s mentality in a period of agrarian society facing abrupt changes to its climate. It also shows how society reacted throughout the different stages of the Little Ice Age. Beheringer’s paper demonstrated this and showed how governance, society and citizens interlinked, something you don’t get in a quantitative approach. Outlining how witch-hunting evolved due to changes in economic/agricultural condition will expose the dark side of our ancestors.

Some segments of European society associated witches with causing hailstorms. The first systematic witch hunts occurred in the alpine valley, and parts of Switzerland during the 1430s. Only during the 1480s that authorities like the Church accepted the association of weather making with witches which caused bad harvest. However, people’s mentalities towards witchcraft started to converge as climate worsen. The extreme weather in these periods 1560-1574, 1583-1589 and 1623-1630 all contributed to the convergence;

The 1560s had immense snowfall in winter and thaw and rain in spring and summer. This causes major disruptions to agriculture. For example, in Germany it caused inundations which poisoned fields, thereby causing cattle diseases, rising infant mortality and outbreak of epidemics. Some believed it wasn’t the witches like the orthodoxy of Lutheran theology which saw the events as a signs from gods. Opinions differed in small political entities where they often scapegoated the witches for their misfortunes and condemned them to persecution. Eg in the territory of Wiesensteig 63 women were burned each year during the 1560s. Other cities with more complex administrative system saw this as inhumane and places like Stuttgart managed to stop the local witchcraft persecution after one burning.

      The 1580s saw a dramatic turn where witch hunts grew into revolutionary dimensions. Why? Because the socico-economic and ecologic condition worsen. Conflict occurred between the demographic movement, continuous population growth and the narrowing of the food supply. It caused hunger and epidemics and created enormous psychological stress among contemporaries.

     Most local officials in big cities were reluctant since their laws don’t recognise witches to be the cause of weather changes. Combined with inefficient legal administration it meant people took matters into their own hands. Organising witch hunts themselves, capturing and making them confess before delivering to the local authorities. Additionally, for the first time it involved members of high authorities like ruling oligarchies.  In 1586-1587 witchcraft accusation reached their climax in England and France. Large scale witch hunt just began and gaining momentum in Scotland and Germany. On the other hand, some European countries managed to suppress popular demands for witch hunts during the end of the 16^th century because the elites of territorial state felt less endangered and regain power over its citizens.

The climate changes continued to the 1620s. During the last week of May winter returned ad temperature dropped in the midst of the vegetation period further damaging food supply. The abrupt climate changes coupled with socico-economic crisis in Germany has meant that there were new demands for persecutions and created large scale witch hunts. Additionally, many independent feudal lords, counts, prince-abbots or small, rural towns supported the persecutions, sharing the superstitious beliefs of their peasants. This ultimately increased and promoted further witch hunts.

I think is important to give a detailed account of the changes in those periods because this is the only way to understand the full extent of how society worked in times of crisis. The prolong period of abrupt climate changes exposes the inherent weakness of humanity. The administrative power of governments breaks down under popular demand, and in extreme case people taking it in their own hands. The mentalities of individual (from peasants to high-society individuals) changes (and for the worse by searching for scapegoats) as these climate events progressively worsen. With the benefit of hindsight, I think these societies were barbaric, but it seemed like the ‘right thing to do’ if you lived through that period. Could the same thing happen to our modern society if we experience similar or even worse socio-economic and ecological disaster? How would our morality change in time of crisis if we experience global hardship due to climate change? Above all this has shown how society plunged into chaos and disorder. Could this happen to our modern society?