For decades, sea level rise has been a global phenomenon. But it happens slowly, on a scale measured in fractions of an inch per year. You may not notice unless you live near the coast, when high tides seem to linger longer and flood streets or when a once-regular nuisance like a sunny day storm surge sends water rushing inland and overwhelms storm drains.
Scientists know that this is due mainly to melting glaciers and ice sheets, but also to thermal expansion of ocean water as it warms. Moreover, climate change is amplified by negative feedback loops that could speed up melting of Antarctic glaciers and disintegration of coastal ice shelves.
Rising sea levels threaten coastal life around the world. They can displace people from their homes and cause economic and social disruptions. They can damage important infrastructure such as roads, bridges, subways, drinking water supply systems, oil and gas wells, power plants, sewage treatment plants and landfills. They can increase flooding, contaminate freshwater supplies and destroy wildlife habitats. They can also erode coastlines and degrade the services that coastal wetlands and marshes provide, such as natural flood control and critical ecological habitat.
In addition, sea level rise exacerbates the destructive effects of hurricanes and major storms. Inundation from a hurricane or severe storm raises water levels, leading to a surge that can cause dangerously high waves and strong currents that can damage buildings, overturn boats and disrupt coastlines for miles inland. This can also contaminate soil and groundwater with salt.