Beyond climate change: Sea level rise affects your physical, mental health

Sea level rise is often viewed as an environmental hazard, but it also threatens health and well-being.

Sudden floods cause loss of life and property, but saltwater intrusion slowly contaminates drinking water and the soil in which our food grows, threatening both physical and mental health.

In light of the rising threat, The Lancet has set up a commission on sea-level rise, health, and justice. It is supported by the World Health Organization’s (WHO) Asia-Pacific Centre for Environment and Health (WHO ACE), to generate science-backed policy recommendations to deal with the challenges of sea level rise.

“This is not only a climate problem; it is a health crisis, a justice crisis, and an urgent call for collective action,” Dr Jemilah Mahmood, Commissioner at Lancet Commission and Executive Director at Sunway Centre for Planetary Health, Sunway University, Malaysia, said.

WHY IS SEA LEVEL RISING?

There are two primary reasons why sea levels are rising, and both are linked to human-induced climate change.

As the Earth becomes warmer, seawater undergoes thermal expansion. At higher temperatures, water occupies more volume.

Another factor is the rapid melting of glaciers and polar ice sheets. As this ice melts, the run-off flows into the oceans, thereby increasing global water levels.

Sea level rise is one of the key indicators of climate change. According to the European Union’s Copernicus Climate Change Service, the global mean sea level has risen by an average of 3.7 mm/year since 1999. Until 2025, this accounted for a significant 9.38 cm increase. Around 30% of this can be attributed to thermal expansion, while the rest is because of the melting of glaciers and polar ice caps. Localised sea level trends can be significantly different from global patterns.

CONTAMINATION AND HEALTH CONCERNS

Saltwater intrusion into freshwater resources is one of the worst consequences of sea-level rise. Salinisation compromises the quality of drinking water, making it non-potable.

According to water and climate expert Ranjan Panda, society and policymakers seem to have normalised drinking water quality issues. “While we rightly focus on urban sewage and seepage contamination, a huge chunk of our coastal population is suffering from saline-contaminated water, and we don't seem to give it the same attention,” he said.

Panda also added that for coastal communities, seawater level rise doesn’t begin with floods. It begins with your drinking water turning unsafe.

In areas like the Sunderbans in West Bengal, parts of Bangladesh, Vietnam's Mekong Delta, and Pacific island nations like Tuvalu, saltwater intrusion is already affecting millions of people.

Saline water doesn’t just “taste” bad. Increased salt intake over time can cause elevated blood pressure, cardiovascular diseases, kidney diseases, and a higher risk of pre-eclampsia in women. A study published in the Hypertension journal in 2025 found that drinking salty water is associated with higher blood pressure, hypertension, and albuminuria.

For women, this is worse.

“During my decades of working with communities along the coastal Bay of Bengal, I have seen firsthand how women’s drudgery and exposure to disease increase significantly due to the salinisation and contamination of water sources,” Panda said. “This highlights another critical dimension: the gender inequality being perpetuated by climate change and sea-level rise,” he added.

Seawater intrusion increases the risk of pathogen infections and subsequent diseases such as diarrhoea, cholera, typhoid, and other gastrointestinal illnesses. Communities that lose access to freshwater are forced to drink from contaminated sources. A 2023 WHO estimate found that around 1.4 million deaths could be avoided each year if people had access to better water, sanitation, and hygiene facilities.

Rising sea levels and subsequent floods stress sanitation infrastructure, mixing floodwater with wastewater and spreading microbes. A 2024 analysis published in the Springer Nature Link journal found that cases of leptospirosis, a bacterial disease, increased in the post-flood phase in Kerala in 2018 and 2019.

Inundation of land can also create still-water pockets, which become breeding grounds for mosquitoes and other disease vectors. Warmer temperatures are already increasing the geographic range in which these carriers are active and potent. A combination of these two factors can increase incidences of vector-borne diseases.

DISPLACEMENT AND MENTAL HEALTH

Physical health challenges from sea level rise are only one layer. The deeper, compounding crisis is mental health, Panda said. This includes anxiety from uncertain futures, trauma from displacement, loss of identity and belonging, stress from livelihood collapse, erosion of rights and entitlements, and the weakening of social protection systems.

Rising sea levels can lead to coastal erosion, more frequent flooding, and the displacement of coastal communities, causing stress and mental health problems. Displaced communities often have to live in overcrowded conditions, with poor sanitation and limited access to healthcare facilities.

While megacities like Mumbai and Chennai are highly vulnerable to flooding and infrastructure stress, the most severe human vulnerability lies in poorer, low-lying regions, Panda said. He added that outmigration because of stress in rural coastal communities is often reframed as positive adaptation, while similar woes of urban populations make headlines. Social vulnerability adds to mental health issues, which can go unnoticed, especially in already marginalised communities. “Historically, ingrained gender inequalities make women much more vulnerable in these regions, especially concerning the contamination of water sources and the heavy burden of distress migration.”

MALNUTRITION AND AGRICULTURE

Saltwater intrusion into coastal agricultural lands affects the quality of crops and soil fertility. This is a significant challenge for the people of the Sunderbans delta, where sea level rise is driving a reduction in the availability of land for agriculture and affecting nutrition for locals who have limited resources to buy food elsewhere. This translates into food insecurity, rising food prices, and malnutrition. Childhood stunting, which is a result of chronic malnutrition, carries lifelong consequences for the immune system and cognitive development.

PUBLIC HEALTH CHALLENGE

Sea level rise doesn’t happen in a day, and is not a single event. It is a consequence of years of environmental neglect and is evolving as a massive challenge for public health.

“The current situation can be summarised as: we respond to disasters, but we do not respond to deterioration,” Panda said. “Drinking water contamination and the resulting mental stress are deeply interconnected and drive many other vulnerabilities in coastal communities. This is a real health emergency.”