Rising sea levels are among the most urgent and far-reaching consequences of a warming planet. As global temperatures increase, two key processes are driving oceans higher. One is the melting of glaciers and polar ice sheets and the other is the thermal expansion of seawater as it warms.

Both processes are direct results of human-induced climate change, caused largely by the release of greenhouse gases through activities such as burning fossil fuels, deforestation and industrial emissions. What was once a gradual environmental shift has now become a rapidly accelerating crisis, placing coastal communities, ecosystems and economies at growing risk.

The impacts of rising seas are already being felt around the world. Low-lying island nations and densely populated coastal regions face more frequent and severe flooding, coastal erosion and saltwater intrusion into freshwater supplies and agricultural land.

In many places, even high tides are enough to cause flooding, a phenomenon known as “sunny day” or tidal flooding. As sea levels continue to rise, millions of people may be displaced, with entire neighborhoods, cities and cultures at risk of being lost to the ocean.

Natural ecosystems are also under threat. Coastal wetlands, mangroves and estuaries, which are the vital habitats that support biodiversity and provide natural protection from storm surges, are being submerged or eroded. The loss of these environments not only endangers countless species but also weakens the natural defenses that protect inland communities from extreme weather and rising waters.

Warmer, saltier oceans also disrupt marine ecosystems, affecting fisheries, coral reefs and the people who depend on them for food and income.

Addressing sea level rise requires both urgent mitigation and forward-looking adaptation. Reducing greenhouse gas emissions is essential to slow further warming and limit the extent of future sea level rise.

At the same time, cities and countries must invest in adaptive strategies, strengthening coastal infrastructure, restoring natural barriers and planning for long-term resilience, including managed retreat in areas where protection is no longer feasible.

Rising seas are not a distant possibility; they are a present and escalating reality. The choices made today will determine how much coastlines will change, how many communities will be affected and how well the world can adapt to a challenge that is no longer on the horizon, but already at our shores.