Advice from a historical geographer: Climate change could lead to severe social turmoil

Dr Pei Qing joined the Department of Social Sciences in 2016. Before joining the department, he was a fellow at the University of Cambridge, UK; a Swiss National Science Foundation fellow at the University of Zurich, Switzerland; and a Post-doctoral fellow in the University of Hong Kong. His research interests range across both physical and human geography, primarily encompassing climate change and human society, contemporary environmental problems and policies, and issues regarding sustainable development. Dr Pei is now an Associate Professor of the department.

In this issue of FLASS FORWARD, Dr Pei shares with us how he combines the strengths of human geography and physical geography in his research on climate change. He also tells us how severe the economic, social and political consequences of climate change could be.

A: I am a historical geographer. My research bridges physical geography and human geography, particularly in the field of climate change and social responses in human history. Through my study of physical geography, I explore the plentiful scientific evidence there is for climate change. Meanwhile, my study of human geography casts light on how society has responded to climate change throughout history.

A: Social responses refer to the social consequences of climate change, which are usually composed of positive and negative responses. Generally speaking, warm weather and affluent rainfall is more favourable for agricultural production. That is to say, agriculture usually thrives in a place with a favourable weather and climate. Along with wealth accumulated from agricultural development, and with other favourable factors coming into play at the same time, industrialisation is more likely to occur with a solid agricultural basis. These are the positive social consequences.

On the other hand, climate change might occur in the form of cooling and drought, which were more disastrous to human societies in the pre-industrial era. Besides climate change, natural disasters can cause massive and immediate damage and destruction to harvests, as well as agricultural infrastructure such as irrigation systems and agricultural machinery. The ecological stress caused by climate change and natural disasters would ruin the food production capacity of a farming society. According to the Malthusian Theory, when a population grows faster than the food supply to the point the imbalance becomes severe, epidemics, famines, and wars are triggered.

Other aspects of social responses include adaptation and resilience. I am also quite interested in drawing lessons from history about how social adjustments and social policy may enable humankind to better adapt and become more resilient to unexpected climate change.

For instance, when the living condition of a place deteriorates, people will likely respond to the environmental challenges by migrating to a more livable area. A society with more mobile populations can better cope with the negative impacts of climate change if we emphasise the importance of migration as an adaptive choice. Historical records show that the negative impacts of climate change became intense in mid-17th century China. The drop in agricultural output due to widespread droughts caused severe famines and social instability, which indirectly led to the demise of the Ming Dynasty (1368–1644). However, the Jurchen migration and related strategies helped them to survive and thrive during this period.

Another example of an adaptative response is the development of agricultural engineering, such as irrigation. The famous Dujiangyan (都江堰) in Sichuan Province, which is both an irrigation and flood control system, increased the buffering capacity of residents in the area when facing ecological stress.

In addition, maize and sweet potatoes were introduced to China in the Ming Dynasty. Maize and sweet potatoes are starchy plants that can grow even on hillsides and tolerate relatively dry weather. The introduction of maize and sweet potatoes was another successful resilient case. These two crops were able to serve as a staple food and increased the variety of food. The progress and prosperity seen in late imperial China was partially due to the increased supply of staple food.

Therefore, climate change could have pronounced economic and even political effects. However, the more a community develops its adaptability and resilience to cushion the impacts of climate change, the more likely its people can survive the threats from climate change.

A: China and Europe are the two geographical regions under my research focuses. Europe experienced the Little Ice Age (LIA) between 15th and 19th centuries when temperatures dropped noticeably. The cold climate of the continent greatly reduced agricultural output, and Europe became vulnerable to famine and other kinds of social unrest.

There was evidence that cold weather also hit China starting from the 15th century, leading to a period of social and political turmoil in the imperial China. The LIA was a tumultuous time for both Europe and China. As Europe and China differ greatly in their economic and political systems, religious beliefs and cultural traditions, the only factor that explains the similar occurrence of social turmoil is climate change.

A: History tells us that the occurrence of a social crisis often coincides with times when the climate is extremely cold or dry. This is because crops fail to grow under the extreme weather, which is usually followed by famine and social turmoil. This has had further implications on the political, military, economic, social and cultural aspects of China’s dynasties.

There is a lot of evidence from historical analysis that supports the idea that climate change leads to social and economic upheavals. Whenever the economic output of a society shrunk, the nutritional intake and quality of life of its people declined as well. The typical consequence of a weakened economy and malnutrition among people was the weakening of the overall resilience of the society and a hastened spread of infectious diseases.

For example, in China, history provides a lot of case studies on the relationship between social instability and extreme climates. The last years of the Ming dynasty were a period of cold weather. The late Ming China was an era of frequent and severe droughts. During the reign of the Wanli emperor (1572–1620), China was hit by three severe droughts, all of which caused outbreaks of plagues. The epidemic of the late Ming Dynasty eventually ran out of control and spread to North China. According to Chronicle of Chongzhen Emperor (崇禎實錄), thousands of people died from the epidemic in the capital. When the epidemic finally ended, the 100,000-strong Ming army had diminished. With fallen numbers and the shattered morale of its troops, the Ming Dynasty was overthrown by the elite forces of the peasant rebel leader Li Zicheng.

A: The success of my research depends largely on how much evidence I can collect to establish the climate pattern of a particular period of time. These pieces of evidence can be collected from historical archives, chronicles or other historical sources, or through scientific means on natural proxies, such as tree rings. Many of these ancient books containing climate/weather information from hundreds of years ago are scattered around the world and remain undigitised. Sometimes, I need to go to local libraries or archives to find relevant information. It is a time-consuming task to dig out relevant historical information about climate change. Finding high-quality natural proxies, such as tree rings, is never easy either.

A: I think my interest in research is the biggest motivation. This is a fascinating area, at least for me. I think, as researchers, we need to identify a topic that really appeals to us. My research approach combines the strengths of physical geography and human geography. This is an approach that rides on the knowledge of humanity studies and the findings of scientific explorations. I believe it provides an innovative perspective on the issues of climate change and social responses, which makes my research work interesting and meaningful. In Chinese intellectual tradition, history and geography are inseparable (史地不分家). In reality, however, there are not many scholars that use a quantitative approach to measure the impacts of climate change on human societies in the pre-industrial era. I am trying to make some breakthroughs in this regard. I feel real joy every time a breakthrough is made.

A: My studies show that the impacts of climate change can sometimes last for decades or even hundreds of years. Even if climate conditions grow less harsh, the impacts of climate change on human society will still take many years to be resolved. Understanding the fact that climate change can have a prolonged influence on people’s lives enables us to better appreciate the historical study of climate change. Furthermore, an understanding of the past can help us better cope with the future.