Sunday, November 18, 2012

When Are We Due For It?

History has seen the rise and fall of many large and powerful cultures. Romans, Mayans, Akkadians, none of these historic empires have lasted in much more than memory and artifacts. But their decline and eventual disappearance is often a source of intense study and speculation, since many of them don't have clear records of their declining years. However, recent evidence has shown correlations between shifts in the local climate and the disappearance of these large civilizations.

The Mayan empire existed in Central America for around 2000 years before it faded back into the mists of time. The reason? Well, that is still a matter of speculation, to some degree. However, there are some theories that are particularly prominent.
"Some believe that by the ninth century the Maya had exhausted the environment around them to the point that it could no longer sustain a very large population. Other Maya scholars argue that constant warfare among competing city-states led the complicated military, family (by marriage) and trade alliances between them to break down, along with the traditional system of dynastic power. As the stature of the holy lords diminished, their complex traditions of rituals and ceremonies dissolved into chaos. Finally, some catastrophic environmental change--like an extremely long, intense period of drought--may have wiped out the Classic Maya civilization. Drought would have hit cities like Tikal--where rainwater was necessary for drinking as well as for crop irrigation--especially hard."
 If you take some additional time to look at these theories, it is easier to see that they could all be part of the same sequence of events. If we start with the drought, then that would lead to the exhaustion of agricultural supplies and means, as well as drinking water and possibly a primary means of transportation. No longer able to sustain the population that exploded with the preceding period of high rainfall and agricultural windfalls, the land began to lose potency, and the people began to suffer. This situation usually leads to civil unrest, and considering the leaders of the culture were also holy figures, they might even be seen as part of the cause of the people's misery. This would lead to the breakdown of government and trade alliances, as people stop listening to distant authorities, and start keeping supplies that might have been previously sent to the capital. As you can see, these possible causes don't have to be mutually exclusive, and in fact become more plausible when combined. This particular series of events has seen increased scientific evidence to its viability as well, with the time of the drought correlating with the time frame of the Mayan civilization's decline. As this hopefully demonstrates, a shift in the climate patterns can have a sudden and drastic impact on a society, to the point that it collapses.

Another example of such shifts in climate causing a societal collapse is the Indus (or Harappan) civilization that was established in the area of modern day "Pakistan, northwestern India and eastern Afghanistan." However, climate shifts also contributed to the establishment of the civilization, since the region was formerly inhospitable due to extreme weather and flooding that was strong enough to sweep away what people would try to build. However, as the monsoons responsible for this extreme weather became more gentle over the years, the flooding became gentle enough that it became an integral part of the farming process in the region. However, this process continued instead of halting in this "Goldilocks status," and since the river that supplied and nourished the region was apparently only fed by rain, with no large body source, the decline in rainfall also meant a decline in available water. In this case, as the river dried up, many people moved to other regions. Some were able to continue farming, since the rains still came, they just would not have been able to produce enough food to feed the city populations that had peaked during the prosperous period of the civilization's history. In this case, the fall of the civilization was a matter of time and circumstance. Unfortunately, without much cause to notice the gradual (oh so very gradual!) change in the weather patterns over the years, and no records to provide a warning (writing was developed during its time, but not from the start), the civilization was doomed to fall as the climate continued its drying trend. So, it becomes difficult to blame the fall of the civilization on their lack of foresight, when they didn't have much hindsight either. Besides, the society lasted for around 2000 years, which would probably span hundreds of generations of people, who didn't have any reason not to take advantage of such a pleasant, fertile region. At least their activities (supposedly) didn't contribute to the climate shift, since it was already part of an established trend.

Which brings up my last point- if a society can collapse due to climate shifts that are already occurring due to shifts in global temperature currents and the like, what will happen when something like this happens on a global scale? Unlike the Harrappans, we won't have anywhere to go if we are managing to afflict the climate processes of entire regions of the globe. We have already seen some of the warning signs of radical changes in the weather- the drought over the summer, Hurricane Sandy's impact on a region that normally doesn't see such violent weather, and generally rising temperatures. Unlike the civilizations of the past, we can tell what is driving the shifts in the climate now- heck, we can even identify contributing factors to their climate shifts. The question is, will we do anything about it, to prevent a permanent shift in global habitability, or will we simply continue along our current path of self destruction?

Extra links:
Roman Empire studies
http://www.groundwatergo.com/blog/the-top-5-ancient-civilizations-destroyed-by-climate-change/
Decline of Akkadian Empire at start of 300 year long dry spell

No comments:

Post a Comment