Climate change causes collapse of Angkor civilization

“I find it hard to believe that the Angkor Wat civilization collapsed due to drought. This region has tropical rainforests and gets a lot of rain with the biggest lake in Asia called Tonle Sap. How could rice farming have been destroyed by drought?”

This was the question I received during my course on climate and civilization at a university. The Angkor Wat civilization created a huge empire by unifying what’s now Vietnam, Myanmar, and Cambodia, building a strong economy based on rice farming. However, continued drought from El Niño plummeted its rice supply, causing the empire’s collapse into tropical rainforests. Even these days, a strong El Niño causes a severe drought in Southeast Asia.

The late professor of geography at Yale University Ellsworth Huntington focused on the fact that many large countries in the past either prospered or perished depending on how advantageous or disadvantageous climate conditions were. Indeed, climate change was the cause of the prosperity or collapse of civilizations. For example, the Mesopotamia civilization, which is the first civilization in human history. As city states, such as Uruk founded by Sumer, began to emerge, a civilization was born and the region was unified by the Akkadian Empire. However, a severe drought continued for about 300 years from 2200 B.C. with the temperature dropping by two degrees Celsius. A drought and an average temperature drop of two degrees Celsius are critical to the growth of crops. Once its economy collapsed, the Akkadian Empire had no choice but to disappear into the mists of history.

The next example is the Egyptian civilization. As its climate changed from dry to humid, the northern half of Africa became a wet savanna. Plants and trees grew in the Sahara and dry savanna with birds, animals, and fish prospering. The repeated climate of warm and cool controls the Nile’s flooding, which contributed greatly to the foundation of the ancient empire. Abundant water in the Nile led to the growth of grain production, leading to the rapid increase of populations and the birth of the Egyptian civilization. Until the sixth dynasty from the Early Dynastic Period to the Old Kingdom, a warm climate with an adequate amount of rain had continued. However, as climate change pushes down the Intertropical Convergence Zone to the south, the Sahara went through desertification.

“The storehouse is empty and its keeper is stretched on the ground. [...] Indeed, public offices are opened and their inventories are taken away; the serf has become an owner of serfs,” Egyptian prophet Ipuwer wrote of the famine at the time. Egypt was in chaos for 141 years after the collapse of the Old Kingdom due to climate change, which was followed by the First Intermediate Period, until the Middle Kingdom emerged.

Climate change destroyed not only large empires but also small civilizations. The Minoan civilization in the Aegean Sea disappeared due to volcanic eruptions and Tsunami. The Petra civilization in Jordan collapsed as an earthquake destroyed its water management system. The Wubar civilization in Oman was buried under sand as an underground limestone cave collapsed due to heavy rain caused by the Monsoon belt moving to the north.

Climate change that destroyed numerous civilizations in the past is nothing compared to what we are facing now. Scientists warn that the end of the Anthropocene is getting closer. The late renowned theoretical physicist Stephen Hawking warned that humans need to get off planet Earth within 100 years and find another planet to call home if our species was going to survive.