Mankind at a Crossroads: Water and Climate Change

March 22 was World Water Day. Mizuno Tetsu reports on the growing sense of crisis in Japan and around the world about water shortages exacerbated by climate change.

There are concerns over the depletion of water resources due to population growth and climate change. The United Nations predicts that the world’s population will increase by some 2 billion in the next 30 years, from 7.7 billion today to 9.8 billion in 2050, rising to 11.2 billion in 2100. Accordingly, global demand for drinking water will rise. It is said that 97.5% of water for mankind today is seawater, and that only half of the 2.5% surface water is available for drinking. Water resources are used for sanitation, food production, agriculture, and energy generation as well as drinking water. However, scientists around the world have pointed out that as global temperatures continue to rise due to climate change, the depletion of global water resources will become increasingly likely.

Needless to say, water is a shared global resource.

Growing Sense of Crisis

The UN has designated March 22 as World Water Day. The theme of World Water Day 2020 was “Water and Climate Change,” calling for five changes: take five-minute showers, eat more plant-based meals, don’t throw away edible food, turn off tech, and shop sustainably.


Further, based on the “UN Campaign for Individual Action” (https://www.un.org/en/actnow), the UN advocates 5-minute showers, bring own bag, drive less, lights off, local produce, plant-based meals, recycle, refill and reuse, unplug, and zero-waste fashion, under the catchphrase “Start with ten simple actions!”. Japan is stepping up its efforts in response to this.

The OECD predicts that over 40% of the world’s population will suffer from severe water shortages by 2050, with the World Economic Forum ranking climate change and water as the top major risks in its Global Risk Report 2020. The international NGO Water Aid’s “On the frontline—The state of the world’s water 2020” points out that “By 2050, the number of people who will struggle to get water for at least one month every year will have swollen to five billion2—so over 50% of the world’s population.”

We are living in a time of unprecedented climate change, as evidenced by severe droughts, devastating floods, and frequent typhoons. Water and climate change are closely linked. In terms of the UN Sustainable Development Goals (SDGs), SDG 6-1 states, “By 2030, achieve universal and equitable access to safe and affordable drinking water for all” and SDG 13-1 states “Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.”

Advance of Global Warming

The effects of global warming are being felt in Japan. In the fall of 2019, Japan was hit by heavy rainfall from Typhoon Hagibis, and in 2020, the meander of the Kuroshio, a warm ocean current in Japanese waters, raised Japan’s sea level by 8.7 cm. According to the Japan Meteorological Agency, the sea level has been rising since 1980 due to climate change, and is expected to continue to rise in the future. This has led to concerns about increased storm surge damage. In fact, the seawater temperature around Japan is rising. As the sea temperature rises, water vapor increases, humidity rises, and heavy rains become more frequent, causing more flooding. Once floods occur, pollutants enter the water supply, creating unsanitary conditions. 


Flood damage caused by Typhoon Hagibis (Tonegawa Bridge in Abiko City, Chiba Prefecture)


Although Typhoon Hagibis caused damage unprecedented in recent years, the recovery from flood and drought damage was relatively quick, made possible by the fact that water and sewage systems were in place. To prepare for the impact of global warming in the future, infrastructure must be improved and strengthened. However, the problem is more serious in developing countries where infrastructure is not sufficiently developed. Moreover, in areas where water is scarce, the water contained in the soil tends to evaporate more easily, resulting in more extensive water shortages and droughts. As global warming progresses, situations such as this could lead to cross-border tensions arising from a scramble for water.

In recent years, climate change has been so dramatic that it is unpredictable on the basis of previous observation data. Not only large-scale typhoons but also short periods of intensive heavy rain such as so-called “guerrilla rainstorms” have caused short term flooding in urban areas, affecting not only the functions of water infrastructure, but also disrupting urban functions such as electricity and transportation, in turn impacting economic and social activities.

Water Resources and Cross-border Conflict

More than 200 international rivers and lakes are valuable water sources for several countries, and conflicts have arisen due to the fact that countries with economic power claim priority usage rights. For example, prior to 2010, Egypt monopolized the right to use the Nile, which is a water source for nine countries including Egypt, Sudan and Ethiopia, giving rise to disputes over the allocation of water for power generation and domestic use.

In Asia, a problem faces the Mekong River that flows from China to Vietnam. China’s construction of a large dam upstream without the consent of its downstream neighbors has resulted in rapidly dropping water levels in Cambodia, Thailand, Laos and Vietnam, causing severe damage to agriculture, fisheries and ecosystems. One contributing factor is China’s growing population and developing economy. China has a population of around 1.4 billion, constituting some 20% of the world’s population, yet its water resources account for only 6% of the world’s total. As the population continues to grow, securing water resources has become an important issue both for the improvement of people’s lives and continued economic development.

Another water resource under threat is the Amazon River. Flowing through seven countries including Brazil, Bolivia and Peru, the Amazon River is the world’s largest water resource, surrounded by forestry resources known as the “lungs of the Earth.” However, this water resource is in crisis due to global warming, large-scale deforestation, and excessive water extraction.

Not only international rivers but forests in the upper reaches of rivers too produce clean water, prevent sediment runoff, help preserve national land, and support industrial development. The destruction of forests leads to the pollution of rivers and impacts marine ecosystems. The water resource environment will be greatly impacted if dams are not appropriately constructed and managed.

Affected local communities both upstream and downstream need to work together to manage water resources. The SDGs call for international cooperation, emphasizing the importance of “transboundary integrated water resources management” to manage water resources so that the economic and social benefits of water can be maximized and enjoyed equitably while maintaining the sustainability of the natural environment and ecosystems.

Integrated Water Resources Management

Japan International Cooperation Agency (JICA) implemented the “Project for Enhancement of Integrated Water Resources Management in The Republic of The Sudan” from 2016 to 2019. The Nile runs through the center of Sudan from north to south. The goal of the project is to improve the quality of policies, strategies, and plans related to water resources management and contribute to the improvement of related projects by making recommendations for a legal and institutional framework through integrated water resources management.

Most of Sudan is in a state of chronic water scarcity with annual precipitation of less than 300 mm. In areas that are not served by the Nile, the national average of access to safe water is only around 55%. According to 2010 statistics, 90% of Sudan’s water resources are used for agriculture and livestock, and only 3% are used for domestic purposes.

JICA dispatched experts in water resources management, surface water development, and groundwater development, provided equipment, and conducted multiple training sessions for staff in Sudan. JICA evaluated the water balance, analyzed issues relating to water resources management, implemented integrated water resources management in specific areas, and made recommendations on strategies, legal systems, and institutions for water resources management.


In industrial and grain-growing areas, a large amount of groundwater is pumped up and excess runoff leads to land subsidence and depletion. The “Ogallala aquifer,” one of the world’s largest groundwater resources extending across the US states of South Dakota, Wyoming, Nebraska, Kansas, Colorado, Oklahoma, Texas, and New Mexico, has been impacted particularly severely. This groundwater has irrigated one of the largest irrigation farming zones in the world, but is in danger of drying up in the next fifty years due to excessive pumping.

A research article co-authored by researchers from the United States and Japan, carried in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on October 20, 2020, entitled “Peak grain forecasts for the US High Plains amid withering waters” (https://www.pnas.org/content/117/42/26145) commented that “[…] Texas and Nebraska had equal irrigated output in 1975; by 2050, it is projected that Nebraska will have almost 10 times the groundwater-based production of Texas.” Further, it warned that “Rapid groundwater depletion represents a significant threat to food and water security because groundwater supplies more than 20% of global water use, especially for crop irrigation.”

Mankind’s Food Problem

The effects of global warming and CO2 emissions continue to be observed in the form of larger scale typhoons and hurricanes, frequent forest fires, and the collapse of glaciers in the Arctic and Antarctic. In December 2020, a massive 315 billion-ton iceberg broke away from Antarctica, while in February 2021, a Himalayan glacier collapsed in India, causing a massive flood. With sea temperatures and sea levels rising, a major crisis is imminent. If the depletion of the world’s groundwater progresses, we will find ourselves confronted with an agricultural and food crisis. If that crisis materializes, at a time when we are so dependent on food imports, the potential for political and economic turmoil is real.

Mankind is standing at a crossroads between conflict or cooperation. We are living in an era that requires us to pool our wisdom and harness our power as human beings.

The exhaustion of underground water from mountains poses a threat to irrigated agriculture. Pictured, rice paddies in Nagaoka City, Niigata Prefecture, with Mt. Yahiko in the background.


MIZUNO Tetsu is a freelance writer.




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