The Earth’s natural salt cycle, a balance honed over millennia, is now being rapidly disrupted by human activity on a global scale. This unsettling revelation, emerging from recent scientific scrutiny, has environmental scientists and policymakers alike sounding an alarm on the consequences of excessive salinization across the planet’s ecosystems.
A comprehensive study, delineated in the esteemed journal Nature Reviews Earth & Environment, exposes the extent to which anthropogenic pursuits – from mining to road de-icing – are accelerating salinization, posing a threat not just to biodiversity but also to human health. This “anthropogenic salt cycle” is supercharging the slower geologic and hydrologic processes that traditionally govern the movement of salt ions within the Earth’s crust and water systems.
Professor Sujay Kaushal of the University of Maryland, a lead author of the study, likens the Earth to a living organism, with salt accumulation potent enough to “affect the functioning of vital organs or ecosystems.” The study authors articulate this concern, suggesting that “if you think of the planet as a living organism, when you accumulate so much salt it could affect the functioning of vital organs or ecosystems.” Kaushal also notes the energy-intensive and costly nature of desalination, the process of removing salt from water, and the environmental conundrum posed by the highly saline byproduct.
The scope of human-induced salinization is staggering, with about 2.5 billion acres of soil – equivalent to the landmass of the United States – adversely affected, as well as significant increases in salt ions in rivers and streams over the past 50 years. This parallels trends in global salt production and consumption, hinting at a direct correlation between human use of salt and environmental impact.
Co-author Gene Likens reflects on the evolution of this research, remarking that “twenty years ago, all we had were case studies. We could say surface waters were salty here in New York or in Baltimore’s drinking water supply.” He emphasizes that the recent study underscores a global, interconnected cycle significantly perturbed by human activities.
Further to soil and freshwater systems, salts are being aerosolized, with saline dust contributing to snowmelt and forming “chemical cocktails” with contaminants, intensifying environmental risks. In the United States alone, road salts – used primarily for deicing – form a considerable part of the problem. They represent a substantial portion of the total dissolved solids entering streams and waterways, with the U.S. churning out a formidable 44 billion pounds of this deicing agent each year.
Policies to mitigate the salt deluge in water systems, including the use of alternatives like beet juice on roads, have been recommended by researchers. Kaushal points out the importance of striking a balance between immediate public safety concerns and the long-term health risks associated with excess salt in water.
Drawing a parallel with climate change, the study’s authors advocate for a “planetary boundary for safe and sustainable salt use,” akin to carbon dioxide level thresholds. While regulation poses its challenges, Kaushal believes it is feasible and necessary, stating that salt is indeed reaching environmentally harmful levels.
Relevant articles:
– Earth’s salt cycle is swinging out of balance, posing yet another “existential threat,” study finds, Salon.com
– People are disrupting natural ‘salt cycle’ on a global scale, new study shows, nsf.gov
– Humans Are Disrupting Natural ‘Salt Cycle’ on a Global Scale, New Study Shows, University of Maryland
– John Barbieri, RSSA on LinkedIn: Earth’s salt cycle is swinging out of balance, posing yet another…, LinkedIn · John Barbieri, RSSA