# A Geological and Political Watershed **Date de l'événement :** 09/11/2025 * Publié le 09/11/2025 ### Date 01/11/2025 ## Chapô **The harnessing of water, enabled by the remarkably stable climate that the Earth has enjoyed for 12,000 years, has accelerated over the last two centuries throughout the world. Climate change threatens to cause a loss of control over the water cycle on which our entire economic organisation and political systems are based. Faced with a major shift in the balance of water resources that is looming and already manifesting itself in record droughts and floods, we must rethink how we share an increasingly scarce resource and, more broadly, our relationship with nature.** ## Corps du texte Who isn’t aware that water is life? This natural element has essential biological functions, both for the life of cells and for the formation and circulation of molecules that are indispensable for the survival of organisms. Its circulation in the ‘water cycle’ is also one of the Earth's major chemical mechanisms, responsible for transporting minerals, shaping landscapes through erosion and sedimentation, and enabling the existence of most of the planet's ecosystems. This is why researchers exploring the possibility of life on other planets focus on the presence of water. It is no less essential to the functioning of our societies. In 2022, a series of record droughts hit several major rivers in the Northern Hemisphere. The lack of irrigation water caused agricultural production in Italy's Po Valley to collapse. Several nuclear power plants in the Rhône Valley had to suspend energy production due to a lack of cooling water. The record low level also impacted navigation on the Rhine. The drought brought thousands of boats on the Mississippi River transporting crops from the United States’ plains to a standstill. On the Yangtze River in China, agriculture and industry were compromised, as was the drinking water supply to several cities. Food production, energy production, transport, public health: the water shortage spared no sector.  The availability of water for our societies’ needs depends on the planet's natural cycles. It depends on temperatures and glaciers, rain and snow, winds and atmospheric pressure. In short, it depends on the Earth's climate. When the climate changes, the amount of water in lakes, rivers and aquifers also changes, as does the amount in oceans and coastal areas.  The climate change underway is transforming the Earth's water, including the rarest and most precious of all: fresh water, which accounts for only 3 per cent of the planet's reserves. This change is already evident in the increased frequency of record droughts and catastrophic floods. Above all, it is causing disruption: the water cycle is increasingly deviating from the norms of the last millennia, thus becoming unpredictable.  How should we think about this transformation? What does it mean for our societies?  A disrupted water cycle ----------------------- More than an academic discipline, history is a means to understand one's own time. Its specificity lies in interpreting the present in the light of the past. In times of stability, we examine the continuities between the past and present. We delve into the roots of the world we inhabit in order to better understand its nature. In troubled times, we examine the ruptures and turning points that change everything. We then look to the past for analogies to help us understand what is happening.  The great transformation of water and climate requires looking far afield to find analogies. Geology provides a starting point. The long timescale of geology is anything but static. On the contrary, radical and sometimes sudden shifts abound in the history of the Earth. Geological upheavals have often been caused by changes in climate, which in turn have affected the presence and distribution of water.  The successive epochs of the Quaternary, the geological period in which we find ourselves, have been punctuated by major glaciations that radically altered rivers and oceans. Rain gave way to snow over large parts of the Earth. Glaciers covered continents and dried up ancient waterways. Ocean levels fell by hundreds of metres. New land appeared, with new lakes and rivers. The transformation underway is changing the Earth's climate in a way comparable to major geological shifts. Today, the concentration of carbon dioxide (CO2), the main greenhouse gas, is 420 parts per million (ppm). It has risen steadily since the mid-nineteenth century, whereas throughout the Holocene, which began 12,000 years ago, it remained at around 280 ppm. This is not the first time in the planet's history that CO2 concentrations have risen so high, but the previous time was 3 million years ago. The Earth's climate and waters were very different then from what they are today.  Now, once again, under the effect of a profoundly transformed atmosphere, the Earth's waters are changing: glaciers are disappearing, oceans are rising, rainfall is becoming erratic, and rivers are drying up. This change is irreversible. In other words, even if humanity were to stop all greenhouse gas emissions today, it would not be possible to return to the previous situation. Only the extent and depth of the transformation can change, and these will only increase if CO2 emissions continue to rise in the coming years. Our ancestors experienced geological cataclysms: humans in the Pleistocene era endured the harsh conditions of the last ice age and inhabited the new lands that emerged as a result of falling sea levels. They abandoned these lands when the melting ice submerged them once again, in catastrophes that only remain recorded in sediments.  These ancient geological and civilisational ruptures alone provide analogies with the present moment. Indeed, since the end of the last ice age and the beginning of the Holocene, 12,000 years ago, the Earth's climate and waters have been remarkably stable. They have been even more so over the last four or five millennia, which correspond to the rise of agricultural civilisations and the written word.  During this period, every year, melting snow fed the rivers of Europe and Asia. Monsoons fed the floods of the Ganges and Nile. Tropical rains swell the flow of the Amazon. In summer and winter alike, the poles remained covered with ice. This will no longer be the case in the future. The world of rivers and streams, rain and snow, seas and oceans that humans on Earth have known for millennia is changing.  While this transformation can be compared to major geological and civilisational shifts, it differs from them in several respects. First, it is caused by human action, not by the forces of the physical universe. Modern societies, through their massive and continuous use of fossil fuels, are responsible for altering the composition of the atmosphere. Second, it is occurring in a world that bears no resemblance to that of our ancestors – a world that has subjugated and harnessed the Earth’s waters. The subjugation of the Earth's waters ------------------------------------- Environmental history sheds light on the great movement to put water to work. This movement took root with the advent of agricultural civilisations around the Tigris and Euphrates, the Nile, the Yellow River and the Indus, that used the rivers to transport goods and improve agriculture. It continued into the modern era with the use of rivers to produce mechanical energy.  However, this movement accelerated over the past two centuries, when the world's waters were harnessed for agricultural growth through irrigation and the draining of marshes; for the development of trade through navigation; for industrial progress through energy production and the discharge of toxic waste; and for urban expansion through the sanitation of cities.  Economic life has been one of the main drivers behind the harnessing of water in both capitalist and socialist societies. The goal of water control was to facilitate the movement of goods, increase agricultural yields, and provide energy for factories. Everywhere, water was channelled to increase wealth, regardless of how that wealth was distributed within societies.  Water control also played a central role in the actions and legitimisation of public authorities through a wide range of means, including public works, the financing of private works, laws and regulations governing usage, the production of knowledge, and even the use of force. A dual rationale was at work: to contribute both to the prosperity of populations and territories and to the power of the states and empires that governed them.  These goals depended on the scientific and technical control of water. Water was harnessed through dykes and reservoirs, ports and canals, turbines and pumps. These infrastructures were designed for the climate that humanity had known since the end of the ice aAge. The height of the dykes, the volume of the reservoirs, the depth of the ports, the flow rates of the canals, the size of the turbines and the location of the pumps were predicated on statistical regularities in the water cycle. They depended on the climateof the Holocene. These statistical regularities no longer apply with 420 ppm of CO2 in the atmosphere. Climate and water change is therefore leading to a crisis in technical water management, which threatens to undermine the foundations of our economies and political systems. A geological, historical and social rupture ------------------------------------------- Thus, two types of rupture currently overlap: a geological one, and a historical and social one. This overlap is dizzying, but we are not powerless to address its implications. History offers no certainties about the future. However, it is difficult to escape the conclusion that, aside from the crucial efforts to decarbonise our societies, a profound transformation is needed in water use. This transformation is only in small part technical. It is first and foremost political. Climate and water change cannot be addressed simply by adapting water infrastructure. The change calls for rethinking how to share a resource with increasingly uncertain prospects. Given the central role of water in economic life, this means establishing priorities and directing resource use and production efforts accordingly. Water sharing must be conceived as an economic planning exercise.  The planning must include measures to restore and preserve aquatic ecosystems. Water must be able to continue supporting life on Earth. Decisions on resource use will become even more complex as a result, but these measures remain necessary to avoid accelerating the collapse of biodiversity, which threatens the well-being and prosperity of our societies as much as climate change.  Climate change also requires a reconsideration of risk sharing and crisis management by political institutions. Anticipating increases in the frequency and intensity of droughts and floods, as well as coastal submersion, and managing the resultant damage, will require unprecedented efforts from local authorities, states, and supranational organisation. But the very legitimacy of these institutions is at stake, through their ability to guarantee the habitability of territories and to protect the lives and property of their inhabitants.  The efforts needed relate both to the organisation of economic life and political institutions and to society's relationship with nature. They demand a mobilisation of intelligence and efforts unparalleled in human history but while unprecedented in scale, they are barely commensurate with the watershed of our time.  **References:** * Chakrabarty, D. 2021. _The Climate of History in a Planetary Age_, Chicago: University of Chicago Press, * Demuth, B., Healey, M., Parrinello, G. and Smith L. C. (eds) 2026 (forthcoming). _Rivers on the Move_, Duke University Press, * Pietz, D. 2015. _The Yellow River. The Problem of Water in Modern China_, Cambridge: Harvard University Press, * Pritchard, S. 2011. _Confluence. The Nature of Technology and the Remaking of the Rhone_, Cambridge: Harvard University Press, * Ross, C. 2024. _Liquid Empire. Water and Power in the Colonial World_, Princeton: Princeton University Press. **_This article was originally published in Conférence issue No. 4, titled "Facing the Environmental Challenge", a publication that sheds light on major contemporary issues and informs public and private decision makers._** ### Thématique `#Environnement` **Langue :** `#Anglais` --- ### Navigation pour IA - [Index de tous les contenus](https://conference.sciencespo.fr/llms.txt) - [Plan du site (Sitemap)](https://conference.sciencespo.fr/sitemap.xml) - [Retour à l'accueil](https://conference.sciencespo.fr/)