Rising seas increase the likelihood that coastal soils will accumulate salts, with direct effects on plant water uptake, soil structure, and long-term land viability. Scientific analyses connect sea level rise to greater frequency of saltwater intrusion into coastal aquifers and episodic seawater overwash during storms. Richard J. Nicholls University of East Anglia has documented how these processes concentrate salts in the root zone, reducing the ability of common crops to extract water and nutrients. The magnitude of impact depends on local elevation, hydrology, and drainage infrastructure.
Causes
Salt accumulates in coastal agricultural soils by three main pathways: slow upward movement of saline groundwater, surface inundation from storm surge and permanent inundation as sea level rises, and irrigation using increasingly brackish water. P. Rengasamy University of Western Australia has emphasized that sodicity and salinity disrupt soil aggregates and impede root penetration, while poor drainage prevents natural flushing of salts. The Food and Agriculture Organization documents widespread vulnerability of coastal and irrigated lands to salinization, noting that human activities such as excessive groundwater pumping and inadequate drainage amplify the effect of rising seas.
Consequences and adaptation
The immediate agricultural consequence is reduced crop yield through osmotic stress and ion toxicity, especially for salt-sensitive species such as rice, maize, and many legumes. Rattan Lal Ohio State University highlights that salinization also drives loss of soil organic matter and microbial function, undermining resilience and carbon sequestration potential. Over time, formerly productive fields can convert to saline-tolerant scrub or require costly engineering to remain arable. Small island states and deltaic regions such as the Mekong and Ganges-Brahmaputra show pronounced cultural and territorial vulnerability because agriculture is tightly linked to food security and livelihoods, and options for inland relocation are limited.
Adaptation options include improved drainage and managed aquifer recharge, selection of salt-tolerant crop varieties, and restoration of coastal wetlands as buffers. These measures vary in feasibility and cost depending on local governance and resources. Without targeted investment and community-level planning, saline encroachment driven by sea level rise will shift agricultural zones, increase economic stress on vulnerable populations, and alter landscapes and ecosystems that support cultural practices tied to land and water.