Water scarcity is the world’s biggest challenge yet, study says

The news that water scarcity is emerging as one of the biggest challenges of the 21st century is shocking. Climate change is pushing rivers and aquifers into drought, and the demand for fresh water is increasing as population growth and economic development continue to drive up demand. However, an often overlooked demographic change – the aging of societies as a result of declining birth rates and increasing life expectancy – will have a surprisingly large impact on global water demand, reducing water use by up to 31% by the middle of this century, according to new research published in Water Resources Research.

This effect is particularly pronounced in parts of Asia. Countries such as China, Singapore, South Korea and Japan are predicted to see a 42–62% reduction in water use as their populations age.

The researchers found that overall water use is declining.

Water demand depends not only on how many people are alive, but also on who they are. A new study finds a strong statistical link between the age structure of a population and how much water it uses overall. Analyzing data from countries around the world, the researchers found that total water use decreases as the proportion of older people increases.

Older people use less water, the study found

Older people generally have lower rates of water-intensive activity than younger people. They may travel less, use fewer resources related to work and leisure, and may use water differently in goods and services that increase water demand. While the study doesn’t claim that aging directly conserves water, such as turning off the tap, it does show that demographic change is reshaping consumption patterns to significantly reduce demand in sectors such as domestic use, agriculture, and industry.

Return most water to rivers or reservoirs after use

According to the researchers’ models, this demographic shift alone could help reduce global water withdrawals from rivers, lakes, and reservoirs by 15–31% by 2050. Even if consumption is low, withdrawals would be much higher if most of the water was returned to rivers or reservoirs after use.

Climate change is making water cycles more unpredictable.

Historically, global water demand has increased. Over the past century, withdrawals have increased as human populations have expanded and economies have developed. Agriculture remains the largest user in most regions. It is no wonder that water scarcity is gaining attention. Recent assessments by the World Meteorological Organization and the United Nations warn that access to reliable fresh water is becoming increasingly insecure around the world. Renewable water, naturally replenished by rainfall and runoff, is not increasing in line with demand, and climate change is making water cycles more unpredictable.

More studies suggest that this pressure is already widespread. Nearly three-quarters of people in more than 100 countries now live in areas that have experienced a total loss of fresh water resources. Countries that are traditionally water-rich (including Canada, the United States, and Russia) and countries with large populations (such as India and Iran) are among those losing significant amounts of water.