Climatic changes have occurred in the past with the exception that they were not human-induced as is the case now
Even if it was pushed away in 2020 due to the novel coronavirus pandemic, the global climate crisis remains where it was, threatening our very existence. And it is not new. Climate change has majorly influenced the decline of human civilisations throughout history, something that holds lessons for us today.
Climatic changes have occurred in the past. With the exception that they were not human-induced as is the case now.
Take for instance, the Anasazi culture in today’s southwestern United States. Today, its descendants, the Hopi and the Zuni, refer to it as the ‘Ancestral Puebloans’. Between 100 AD and 1300 CE, the Ancestral Puebloans produced some of the best architecture in the Western Hemisphere, so-called ‘Sky Cities’ built into the face of canyons.
They also produced pottery and rock art and built roads. However, when the Great Drought occurred in North America from 1276-1299 in North America. Scholars have postulated that this event, along with ethno-political changes in the area may have led to the Ancestral Puebloans abandoning their cliff dwellings and heading south, never to return.
South of the border, in the lush jungle of Mexico’s Yucatan Peninsula, another world civilisation may or may not have ended due to climate change. Between 830 and 950 CE, many Mayan cities stopped building and were abandoned. Many theories have been suggested to explain this event.
One of the strongest is the climate change hypothesis. According to a paper published in 2018 in the journal Science by Nicholas P Evans from the University of Cambridge, annual precipitation may have decreased between 41 and 54 per cent during these years.
There may have been periods of up to 70 per cent rainfall reduction, the paper adds. Relative humidity may have declined to 2-7 per cent below current levels.
However, there is no consensus as to what may have caused the decline in precipitation, with factors suggested including deforestation and changes in tropical cyclone frequency.
Thousands of miles north, on the largest island in the world, Norse civilisation may have ended due to climate change.
According to Viking folklore, Greenland was colonised in 985 AD by a Norse explorer named Erik the Red, so named due to the colour of his hair and beard. The two Viking settlements on the island lasted till 1450 AD. They then disappeared from the pages of history.
Latest research has put forward a completely new sequency of events as to why this decline happened. Climate change features as one of the main factors.
Norsemen settled Greenland to harvest its sources of walrus ivory that was prized in Medieval Europe. They also farmed on the side and not vice versa as was conventionally thought till sometime back.
But around 1257, the climate started cooling due to the eruption of a volcano in Indonesia, kicking off the Little Ice Age. Sea ice as well as sea storms increased. This made the Norse walrus hunts on the high seas very difficult.
Around the same time, Russian walrus ivory as well as African elephant ivory flooded Europe, cutting into the Vikings’ market share. Lastly, the Black Death in Europe meant that their supply lines were strained. All this could have contributed to their extinction.
The Sixth Dynasty in the Old Kingdom of ancient Egypt could have been a victim of climate change.
The conventional view for long has been that the Old Kingdom collapsed after the very long reign of Pharoah Pepi II. The reasons for the collapse were a lack of successors, the rise of provincial chiefs and a lack of seasonal inundation of the Nile caused by climate change.
This has been largely based on a text from the era called the ‘Admonitions of Ipuwer’.
However, more recent scholarship is challenging this view. In his 2012 paper, Yale University historian Joseph Gilbert Manning said that, “State collapse was complicated, but unrelated to Nile flooding history”.
Another civilisation probably ended by climate change is the powerful Hittite Empire that flourished in modern-day Turkey 1600 years before the Common Era.
In his 2015 paper, academic David Kaniewski has cited how the kingdom suffered from drought caused by changing climate around the year 1200 BCE.
The paper reads:
“The kingdom, which relied on the importation of grain from Egypt following the treaty between Ramses II and Hattusili III, had probably long suffered from a shortage of grain …”
One of Hattusili’s successors, the penultimate king of the Hittities, Arnuwanda III “…describes the awful hunger suffered by his father in Anatolia. The King mentioned drought as the main reason,” according to the paper.
Later, political instability brought about by internecine warfare caused the end of the Hittites.
Also in West Asia, Akkad, the world’s first empire could have fallen due to climate change. Experts such as Yale archaeologist Harvey Weiss have for long postulated that climate change caused the downfall of Akkad.
In her 2019 paper, Cambridge researcher Stacy A Carolin cited changes in stalagmite chemistry from the Gol-e-Zard cave in northern Iran to prove that climate change had indeed caused Akkad’s downfall.
Hundreds of thousands of miles to the east, the ghost town of Otrar in Kazakhstan was once a flourishing outpost on the Silk Road in Central Asia.
Its downfall is usually attributed to an invasion by Genghis Khan in 1219 AD. The Khan of Khans had been outraged by the treatment meted out to a Mongol caravan by a local governor of the Sultan of Khwarazm.
However, a 2020 paper states that the real reason for the decline of the town could have been the abandonment of local irrigation canals. They were abandoned due to the erosion of the bed of the Arys river that fed them.
The erosion happened between the 10th and 14th century AD, coinciding with a dry period of low river flows, rather than corresponding with the Mongol invasion.
Besides these instances, there are other, more well-known cases where climate change has caused the end of human societies.
Like the Indus Valley Civilisation in the Indian subcontinent. It has now been proven that shifting monsoon patterns linked to climate change likely caused its rise and fall.
Or the Medieval Khmer Empire in Southeast Asia, whose elaborate system of reservoirs and canals was unable to withstand long periods of droughts, followed by floods.
Or Easter Island in the eastern Pacific Ocean, whose original Polynesian inhabitants brought about climate change by deforesting the island for their statue building and introducing invasive species.
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