As the climate changes, the world’s population grows and economies expand, pressures on the world’s finite water resources will intensify. Climate change impacts the quantity and quality of available water, and with growing populations more water is both consumed and polluted. The attention of policymakers has largely been focused on problems related to the quantity of water that are more visible; droughts and floods are conspicuous events that bring media spotlight and draw public attention. But water quality—being predominantly invisible and hard to detect—goes largely unnoticed.
A new report by the World Bank, Quality Unknown: The Invisible Water Crisis presents new evidence and new data that explores the world’s water quality and its impacts on human health, the environment, and the economy.
To shed light on these issues the report assembled a vast—and perhaps the largest—dataset on water quality gathered from monitoring stations, satellite data, and machine learning algorithms. The report focuses on core water quality indicators: nutrient loads, salt balances, and the overall environmental health of water bodies. These are pollutants that are ubiquitous, more widely measured than others, and targeted by Sustainable Development Goal 6.3.2.
Quality Unknown finds that countries rich and poor alike endure high levels of water pollution. But as countries develop, the cocktail of chemicals and vectors they have to contend with changes.
- Some pollutants, such as fecal bacteria, are a problem primarily in developing countries where 70 to 80 percent of domestic wastewater is released into the environment without treatment.
- Others such as nitrogen—largely the product of fertilizer runoff and untreated human waste—are the pollutants of growing prosperity and tend to increase with GDP.
- And newer emerging pollutants such as plastics and pharmaceuticals are on the rise across the world, irrespective of per income levels.
The report explores the impacts of this changing water cocktail on health, food security, and economic growth. Its findings are disconcerting.
The three deadly threats: NO3, NaCl and BoD
Nitrogen is essential for agriculture, but it is volatile and unstable. Much of the nitrogen applied as fertilizer leaches into water or the air. In water, it may result in hypoxia and dead zones—problems that arise from a lack of dissolved oxygen in the water. In the air, it may form nitrous oxide, a greenhouse gas that is 300 times more potent in trapping heat than carbon dioxide. This is why some scientists believe that nitrogen is the world’s greatest externality, exceeding even carbon.
Nitrogen in water is responsible for fatally inflicting what is known as “blue baby syndrome,” caused by a lack of oxygen in the body. This report finds that those who survive exposure to high doses of nitrogen in their early years endure longer-term damage and grow up shorter than they would have otherwise. Nitrate exposure in infancy can wipe out much of the gains in height (a well-known indicator for overall health) seen over the last half-century.
There is a clear trade-off between the agricultural benefits that fertilizers bring and their consequences for human health. A back-of-the-envelope estimate suggests that an additional kilogram of fertilizer would increase yields by 4 to 5 percent. But, the subsequent runoff brings a risk large enough to increase childhood stunting by 11 to 19 percent and decrease later-life earnings by 1 to 2 percent. This would suggest that the vast subsidies accruing to fertilizers have unintended effects that may generate damages that are as great as, or even greater than, the benefits they bring.
When it comes to food security, we find that agricultural yields fall almost linearly with increased salt concentrations in water. Put simply, more salt in water leads to less food for the world. This is problematic because saline waters and soils are spreading throughout much of the world due to increasing rates of water extraction, sea-level rise, poorly managed irrigation systems and pollution from cities. Enough food is lost due to saline waters each year to feed 170 million people every day—that’s equivalent to a country the size of Bangladesh. These impacts are a particular concern in areas of intensive dryland irrigation where salinity problems are worst.
Finally, given the wide range of contaminants and the endless array of impacts, the report tries to assess the overall effects of pollution on the economy, using an umbrella indicator of pollution, biological oxygen demand (BoD). Essentially, this is when a combination of bacteria, sewage, chemicals, and plastic sucks oxygen from the water supplies. The release of pollution upstream is found to act as a headwind that lowers economic growth downstream. When BOD exceeds a high enough threshold (8mg/L), GDP growth in downstream regions is lowered by a third, on average. As expected, the growth impacts decline with the level of pollution.
In sum, the findings from the report show that poor water quality stymies human potential, reduces food production and jeopardizes economic progress.
The challenge is daunting, but it is not insurmountable. Solutions are available and rendered more affordable and feasible by new technology. Three countermeasures are available, and feasible:
- Information is crucial both as a resource and a rallying cry. The world needs reliable, accurate and comprehensive information, without which there can be no evidence-based policymaking.
- Prevention is better and safer than a cure. To prevent pollution requires that it is measured and regulated. Advances in technology have brought down the costs of effective enforcement.
- Pollution that cannot be prevented must be treated. Investments in wastewater treatment are a down payment for a cleaner future. But all too often they are poorly managed and ineffective. These investments need to be accompanied by incentives that monitor performance, penalize profligacy, and reward success.
With water scarcity expected to increase as populations grow and the climate changes, the world cannot afford to waste and contaminate its precious water resources.