'Megadrought' & Megadeath

‘Megadroughts’ were not a phenomenon that I knew much about until recently, yet it is something that some parts of the US may become all too aware of in the near future. As the name suggests, it refers to a drought event that is extensive in both duration and magnitude, and according to a Telegraph article, poses an imminent threat to the Southwest and Central Plains regions in America. Based upon the original research by Cook et al. (2015), the article discussed the likely generation of incredibly high drought risk in this region, if there is a continuation at current emission levels.

Although, one of these events has not occurred for around 500 years, it is evident in geological and archaeological records that significant social disruption resulted from previous appearances. The most intense of these episodes has been reconstructed with tree ring data, suggesting the occurrence of a 40 year drought in the late 16^th Century. It was also thought to coincide with the death of 80% of the total population of Mexico, owing to two major outbreaks of the ‘Cocoliztli’ disease. It is believed that the rodents who carried the disease increased their food seeking habits during times of drought, and consequently came into greater contact with humans. Similarly, the ‘Medieval megadroughts’ which occurred between AD 900-1300, were thought to have resulted in the mass abandonment of Ansazi settlements. In similar circumstances to the previously discussed collapse of the Maya, political warfare and religious turmoil were also believed to have been very influential, but megadrought is thought to have been a significant destabilising factor.

When this is put into the context of the current situation in the US, the possible consequences are quite disconcerting. Cook et al. 2015 believe that the extent of global warming created by a ‘business as usual scenario’ would generate greater than an 80% risk of megadrought this century; with anthropogenic warming increasing the probability of co-occurring warm and dry conditions. Such an event could last for over five times as long as the catastrophic Dust Bowl event of the 1930s, and would likely produce environmental, social and economic impacts on an unprecedented scale. An ever growing population and depleted water resources will further exacerbate this.

Droughts are considered to be ‘the world’s costliest natural disaster’ and can produce some truly devastating effects. Water scarcity is going to be one the most concerning factors to emerge from a potential increase in these types of events, and may ultimately become incredibly influential in the ability for societies to remain as they are in some of these semi-arid regions. 

An image taken during the recent California droughts, which is potentially experiencing its most intense period of aridity for 500 years. It is also a likely contender for future megadrought occurrences; a big concern considering that the region ranks first in the US in terms of population, economic activity and agricultural value.