NASA reports that global temperatures have risen by about one degree Celsius (1.8F), resulting in sea levels rising by 160 to 210 millimeters (six to eight inches), with nearly half of this increase occurring since 1993. According to the World Meteorological Organization (WMO), global mean sea levels have been climbing faster in the 20th century than in any other century over the past 3,000 years, with last year's average sea level hitting a record high.
Devastating Impact on Coastal Communities
The effects of rising seas are wide-ranging. Guterres warned that communities are being overwhelmed, freshwater sources are being contaminated, and crops, infrastructure, and biodiversity are being destroyed. Critical economic sectors like fisheries, agriculture, and tourism are particularly hard hit. Small island nations, such as those in the Pacific, are among the most vulnerable, with some already facing existential threats due to rising waters. Countries like Bangladesh, China, India, and the Netherlands are also at risk of devastating flooding, as are major cities such as London, New York, and Mumbai.
UN data highlights that one in every ten people globally lives near the coast, amplifying the need for urgent action.
Climate Change: The Main Driver
Human-induced climate change, according to scientists, is the primary cause of rising sea levels. Melting land ice and the thermal expansion of seawater as it heats up are the leading contributors. Ryan Hobert of the UN Foundation explained that while the ocean has been an ally in climate regulation—absorbing excess atmospheric heat—it also expands as it warms, accounting for nearly half of the sea level rise observed to date.
Guterres recently described the situation as an "overflowing" ocean and a "crisis entirely of humanity's making." The warming seas are not only threatening coastlines but also leading to increased salinity, which is affecting agriculture by reducing crop yields and damaging trees.
The Threat to Small Island Nations
Pacific Island nations such as Fiji, Vanuatu, and the Solomon Islands are already facing forced relocations as rising seas threaten their economic viability and the very existence of their homelands. The Intergovernmental Panel on Climate Change (IPCC) has cited studies indicating that countries like the Maldives, Tuvalu, the Marshall Islands, Nauru, and Kiribati could become uninhabitable by 2100, displacing some 600,000 people and creating stateless climate refugees.
Hobert emphasized that curbing global greenhouse gas emissions is the most critical step in slowing the rise of sea levels. For Small Island Developing States, the issue is not only about preserving livelihoods and cultures but about ensuring their survival. The UN stresses that urgent investment in climate adaptation and resilience is needed.
Economic and Health Risks
Sea-level rise is not only a threat to infrastructure but also poses severe risks to public health. Saltwater flooding can destroy coastal habitats, damage agricultural lands, and contaminate freshwater supplies, while also leading to the spread of waterborne diseases and mental health challenges. Countries reliant on tourism are seeing their economies suffer as resorts, beaches, and coral reefs endure damage from rising waters.
As sea levels continue to climb, coastal communities will face worsening crises unless global efforts to reduce emissions and build resilience are swiftly implemented.