Our policies need to embrace the fundamental truth that water is the basis of life.’ – Sandra Postel
Geoffrey Holland – What is the status of the world’s freshwater systems?
Sandra Postel – Let’s begin by noting the three most fundamental attributes of freshwater: it is the basis of terrestrial life; it is renewable but finite; and, it has no substitutes. This means that in contrast to coal or copper, freshwater is much more than a resource or input to our economy. It is the source of life itself. While it might seem like I’m stating the obvious, our management of water often runs counter to this central truth.
By many indicators, freshwater systems – rivers, streams, wetlands, floodplains, aquifers – are in serious decline. Many major rivers – the Nile, Indus, Yellow, Murray, and Colorado, to name a few – are so dammed, diverted, and depleted that they no longer reach the sea for extended periods. As a result, deltas are sinking and coastal fisheries are suffering as river flows no longer deliver sediment and nutrients to them. Up to half of the world’s wetlands have been drained or filled, eliminating the many critical functions those wetlands provide – from cleansing and storing water, to sequestering carbon, to providing critical habitat for birds and wildlife. Globally, dams now disrupt 48 percent of the volume of river flows, which eliminates habitat and vital life-cycle cues for freshwater life. All of this ecosystem destruction is resulting in an enormous loss of life: according to the World Wildlife Fund, since 1970 the global population of freshwater vertebrates has declined by 83%. Stated another way, for every 100 frogs and fish that were around 50 years ago, there are now only 17. That is a dramatic loss of life in a geologic twinkling of an eye.
GH – Can you talk about the planet’s water cycles, and what humans are doing to disrupt those cycles?
SP – Water cycles on many scales, from the local to the global. At the planetary scale, the heating of the atmosphere due to unchecked greenhouse gas emissions is fundamentally disrupting the global water cycle. As the atmosphere warms, it expands, which allows it to hold more moisture. This, as a rule of thumb, means that dry areas will get drier, and wet areas will get wetter. We can expect, and are already seeing, more intense floods and droughts – and these events will intensify.
At more regional scales, we have disrupted the water cycle by mismanaging headwater forests, by blocking and altering river flows with nearly 60,000 large dams around the world (and hundreds of thousands of small dams), by moving water from one place to another, and by disconnecting rivers from their floodplains. While this water engineering has brought much of the world enormous prosperity, it has broken the water cycle—the natural storage and movement of water between the land, sea, and air that sustains terrestrial life and is critical to human prosperity.
GH – The human population has more than doubled in just the past fifty years to nearly eight billion, with 10-12 billion expected by the end of this century. Is there enough freshwater on Earth to meet the demands of that many people?
SP – Yes, there is enough freshwater to meet the needs of the human population, but to also sustain freshwater ecosystems and the diversity of life requires that we shrink our personal and societal water footprints. The average resident of the United States uses 2,000 gallons of water a day to keep his or her lifestyle afloat. Meat-intensive diets account for about half of that water footprint, energy use (transportation, heating, cooling, etc.) for about a third; purchases of material goods from clothes to computers for about 5-10 percent; and home activities, both indoors and outdoors, for another 5-10 percent.
The good news is there’s a lot we can do to shrink our water footprints. A great place to start is to waste less. Every time we throw a cup of coffee down the drain, we’re throwing the equivalent of 34 gallons of water down the drain because growing those coffee beans takes a lot of water. Moreover, if those coffee beans come from Ethiopia, we’re impacting water sources there. Reducing waste is an easy way to conserve water.
Another opportunity is to shift our consumer behaviors. A cotton shirt can take 700 gallons to make – more water than many people use at home in a week. Do we really need so many shirts in our closets? Dietary shifts can make a big difference as well. Eating less commercial beef would shrink our carbon and water footprints substantially, probably more than any single dietary change. So, there’s a lot we can do that if multiplied by tens of millions of our fellow human beings would make a big difference.
GH – You have said that agriculture uses 70% of the freshwater humans consume. What is that doing to the world’s groundwater aquifers?
SP – Agriculture accounts for 70% of global water withdrawals. A good share of that water comes from aquifers – geologic formations that store water beneath the earth. Unfortunately, we are building up a large water deficit in the form of groundwater over-pumping. Large portions of China, India, Iran, Mexico, the Middle East, North Africa, Saudi Arabia, and the western United States are extracting groundwater faster than it’s being replenished. In effect, we’re using some of tomorrow’s water to meet today’s demands. If my estimates are roughly right, 10 percent of global food production today depends on the unsustainable use of groundwater. In India, this figure is closer to 20 percent. This is a worrisome bubble in the global food economy – and it cannot last. Millions of wells in India have already gone dry.
GH – How has public policy contributed to water management failures and also to success stories?
SP – As a general rule, our societal approach to water has been to bring it under human control through the construction of big infrastructure – large dams to block rivers and store water in reservoirs, long-distance diversions to bring water to farms and cities, high levees to control floods, and big pumps to extract groundwater from beneath the earth. In many ways, this approach has been very successful. Indeed, it’s difficult to imagine our world of nearly 8 billion people and $80 trillion in annual economic activity without this vast network of impressive water engineering. Yet, as I stated above, this infrastructure has broken the water cycle and eliminated critical ecosystem functions that support the web of life.
Policies and projects focused on working with nature, rather than against it, and that promote conservation and smarter management of water demonstrate that we can get more benefit out of each drop nature provides. My most recent book, Replenish, offers many such examples. They include the planting of cover crops to rebuild soil health, which increases both soil carbon and water storage. This in turn can mitigate both droughts and floods and increase crop yields. Currently, only about 6 percent of US cropland is planted with cover crops, so incentives offered through state and federal farm legislation could make a big difference. European countries in the Danube Basin are working to reconnect rivers to their floodplains – a way to build resilience to floods, recharge groundwater, expand habitat for fish and wildlife, and simply let rivers be rivers again. At the national level, US legislation passed nearly three decades ago that requires more water-efficient fixtures and appliances has driven down residential per capita water use nationwide. Combined with a voluntary labeling program to guide consumers to more water-efficient appliances, this legislation has built conservation into new homes and offices, saving some 9 billion gallons of water a day – equal to nine times the daily water use of New York City.
GH – What role does treated sewage water have in agriculture?
SP – A surprisingly large share of the world’s cropland is found in and around cities, so the use of treated wastewater for irrigation can make a great deal of sense. Globally, urban and peri-urban farms encompass some 456 million hectares (1.13 billion acres), an area roughly the size of the European Union. (That figure does not include rooftop gardens or small backyard plots.) For regional water managers, recycling treated municipal wastewater to nearby farms can be a cost-effective way of getting double duty out of their water supply while also alleviating pressures on rivers and aquifers. For farmers, the nitrogen and phosphorus contained in the wastewater are valuable nutrients that can reduce the cost of chemical fertilizers. As long as the treated wastewater meets health and environmental standards, and its distribution to farms doesn’t harm a river or other water user downstream, it can be a winning proposition. At the national level, Israel has made great use of this strategy. Today, Israel reuses over 85 percent of its municipal wastewater, and the recycled water meets nearly half of the nation’s irrigation demand.
GH – Industry around the world is generating massive amounts of toxic chemicals, much of which ends up in our waterways and oceans as runoff. What is the answer to that?
SP – In countries that have passed legislation to curb municipal and industrial water pollution, rivers and lakes are much cleaner than they were before. Residents in the United States, for example, no longer worry about rivers catching fire, as the Cuyahoga river outside of Cleveland, Ohio, did in the 1960s. But many chemicals used in everyday products – including sunscreens, plastics, and cosmetics – as well as lawn pesticides and prescription drugs make their way into water supplies today. Most of these chemicals are not adequately tested for their health and environmental effects, so often pose unknown risks to fish, wildlife, and people. In addition, the runoff of nitrogen and phosphorus from farm fertilizers is on the rise in many parts of the world. Such “nonpoint” pollution is rarely regulated, and it poses growing risks to the safety of drinking water and the health of fisheries when it forms toxic algal blooms in lakes and bays. Besides, the decomposition of algal blooms can rob waters of oxygen, creating so-called dead zones that threaten recreational and commercial fisheries. Globally, scientists have identified more than 400 dead zones, and that number is rising.
There is no one fix to these various pollution challenges. It will take more regulation, more incentives, and greater use of the precautionary principle, which essentially says to resist the introduction of a new product or process whose health or environmental effects are disputed or unknown.
GH – Humans have long operated as if we are above and superior to nature. We take much of the planet’s water and other resources for our own use. Is seeing ourselves as a part of nature, rather than detached and superior to nature, a necessary step to creating a life-affirming, sustainable future?
SP – Yes, without question we must understand that we are part of nature, not separate from it and that we depend on healthy ecosystems and the planet’s amazing web of life for our own existence. We still have far to go in embracing this truth. Maybe the tragic fact that a virus called SARS-CoV-2 has killed some 2 million Homo sapiens in a little over a year will instill in us some humility concerning our place in nature.
GH – How does public policy need to change to assure safe and secure freshwater resources for future generations?
SP – Climate and water policies are inextricably linked, which creates the opportunity to solve multiple problems simultaneously. Public policy needs to get bolder now. Last spring, I wrote a piece published in The Hill calling for a Climate Preparedness Corps. Modeled after the Civilian Conservation Corps of the 1930s, it would not only help create millions of jobs, it would address a key lesson we’re learning from the pandemic – the need to heed the experts and prepare for devastating outcomes. Now is the time for governments and communities the world over to prepare for the floods, droughts, wildfires, food shortages, disease, and civil unrest that scientists and intelligence specialists warn is coming. Building more climate-resilient water systems is critical not only to future food and water security but to social and political stability.
Lastly, our policies need to embrace the fundamental truth that water is the basis of life. We talk about water as a “right,” but it is really the planet’s greatest gift. A gift to be shared with all of life. I believe we have an ethical responsibility to manage water in such a way that all living beings, human and non-human, receive the water they need to survive before we humans get more than enough. That may sound radical, but it’s not. It recognizes our interdependence with the rest of life on the planet.
Teaser photo credit: By The Iowa State Department of Agronomy, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10550871