Beyond freshwater, a saline future

As the global freshwater crisis deepens, a shift towards harnessing the vast, untapped saline reserves becomes imperative

Globally, water is broadly classified into two realms: saline and freshwater. Data reveal that saline water accounts for 97.43% of Earth’s reserves, while freshwater only 2.57%, of which rivers contribute a mere 0.0002% of total water. Yet, it is this infinitesimal fraction that sustains most of the terrestrial life on the planet and compels humanity to hinge on it for its very survival.

Despite this fragile dependence, global water crises manifesting as scarcity, conflicts, climate shocks, decay of dams and canals – amidst an ever-rising demand – have done little to shift attention beyond the narrow realm of freshwater. For instance, with the world population projected to swell from eight billion today to about 10 billion by 2050, the demand for food and energy is set to explode dramatically. Groundwater reserves are already in retreat, even as the pressure on surface sources intensifies.

UNICEF estimates that half of the global population is already suffering from water stress. India’s NITI Aayog reports that nearly 600 million, or 45% of the population, are already grappling with a severe water crisis. By 2030, the demand is projected to outstrip supply by nearly twofold. Adding to this, ageing dams constrain the already scarce supply.

One of the primary reasons for
this fixation on narrow freshwater reserves is the entrenched perception
that saline water, with its TDS levels of above 1,000 mg/l, is unfit for drinking, agriculture, and industrial use. The consequences of this dependence are severe because freshwater is finite, whereas demand is not.

Despite this escalating water crisis, global efforts towards mitigation remain focused on conserving and reallocating the same limited reserves. Research aimed at eliminating dependence on freshwater is confined largely to desalination or niche saline-agriculture trials. That the staggering fact – 98% of the world’s water is saline – has not spurred a definitive shift in approach is a major cause of the global freshwater crisis. This crisis is less about hydrology than it is about the mindset and intellectual scarcity.

The prevailing water discourse attributes the crisis to a litany of factors: population explosion, urbanisation, consumption patterns, governance issues, and climate change. Remedies, however, remain restricted to the tiny freshwater domain. Large storage, rainwater harvesting, and water efficiency measures – all reflect strategies that ignore saline water. This restricted approach to solutions is a zero-sum game. As the demand rises, any savings achieved in one sector inevitably reduce allocations elsewhere. And climate change will only exacerbate this imbalance, potentially turning the freshwater crisis into a cataclysm.

Contrary to the widespread belief that saline water is inherently unfit, humanity has already been utilising it for ages. Seafood, with over 1,900 nutrient varieties, has always been part of the human diet, thereby reducing the freshwater footprint. Seas and oceans offer an array of edible and nutritious plants. Species such as Porphyra spp, Monostroma spp, Enteromorpha spp, Laminaria japonica, Hizikia fusiforme, kombu, Caulerpa lentillifera, and wakame form traditional diets across Pacific nations.

From an economic standpoint, several freshwater-dependent crops can be replaced with saline water analogues. Mangrove species of Rhizophora and Ceriops yield excellent fuelwood, while the salt-tolerant Prosopis provides quality timber.

Halophytes, emerging alternative crops, offer potential for food, biofuel, and edible oil production, replacing freshwater-guzzling crops like corn, sugarcane, and palm oil. Saline water varieties of floriculture and horticulture further expand economic opportunities.

Time for the alternative

It is imperative to break free from the dependence on the narrow freshwater domain and turn towards the planet’s vast saline reserves. The conceptual tool enabling this transformative shift is the ‘saline water footprint’, the total volume of saline water used in producing goods and services.

As agriculture consumes 80-90% of the world’s freshwater, replacing freshwater-guzzling crops with saline alternatives would substantially conserve vast quantities of freshwater within its limited 2.5% share. Advancing saline water analogues, from economic opportunities to delicacies, would enhance the saline water footprint while concomitantly reducing the reliance on freshwater-intensive products.

With nearly 38% of the world’s population residing within 100 km of a coastline, the global shoreline (excluding Antarctica) stretching over 2.4 million km, and climate change further exposing vast tracts to saline influence, the potential for expanding this footprint is immense.

But that requires a paradigm shift and reorienting the collective mindset of all stakeholders, policymakers, governments, researchers, and investors, towards recognising saline water as a vast, untapped asset.

Global water policies should, therefore, move beyond fragmented and sporadic experiments and integrate desalination plants, seafood consumption, halophyte cultivation, saline-based floriculture, fuelwood, biofuel from salt-tolerant species, mangrove expansion, etc., into a unified saline water footprint framework. This approach would systematically enhance, monitor, and scale up global saline water usage and investment in research and innovation.

Institutionalising saline water footprint and progressively embedding it across agriculture and industry offers a durable strategy, transforming the freshwater crisis into sustainable water security for generations to come. Thus, as long as the world locks its priorities to its freshwater reserves and ignores the oceans, the freshwater crisis will remain unsolvable. With a coastline newly estimated at over 11,000 km, India should take a lead towards the saline century, thereby resolving its own freshwater crisis, once and for all.

(The writer is Director, Central Water Commission, Government of India; views expressed are personal)

Disclaimer: The views expressed above are the author's own. They do not necessarily reflect the views of DH.