Study: U.S. California's coastline faces grim future as sea levels rise

Rising ocean levels are threatening California's coastline in the U.S., where 70 percent of residents live and millions more visit each year, and the impacts will worsen in the next 30 years, a new study warns.

Sea levels are predicted to rise an average of 0.24 meters by 2050 compared to the year 2000, and the figure could go up by 1.86 meters by 2150, according to the report released last week by the California Ocean Protection Council.

The report is an update to the 2018 version. Researchers said the new findings have provided more certainty since there have been significant advancements in scientific understanding and ability to project future sea level rise over the past six years.

Researchers said two major factors contribute to sea level rise: ocean warming, a result of increasing greenhouse gas emissions; and the melting of land ice.

Sea level rise brings about serious coastal impacts on communities, such as flooding and erosion. Such impacts are projected to worsen in the years ahead.

With the rise of 0.24 meters in ocean level, flooding will become more frequent and severe, occurring throughout the year and posing a grave threat to homes, businesses, and infrastructure like roads and bridges, according to the researchers.

The San Francisco Bay Area, for example, accounts for two-thirds of future flood risk of the California population and property values state-wide, according to the report, while low-lying areas across the state are also at risk, including numerous coastal and estuarine communities, as well as airports, port facilities, transportation corridors, and public utilities.

The new report also revealed that rising sea levels will cause groundwater levels to rise at the same time, which can spread contaminants in the soil and threaten underground infrastructure.

As the sea level rises, the process pushes shallow groundwater closer to the surface, releasing contaminants buried in the soil, the researchers explained.

Another recent study led by the U.S. Geological Survey (USGS) warned that erosion, caused by sea level rise, could make many of California's beaches disappear by the end of this century.

Climate change is altering California's coastline. Rising seas, colliding with more frequent and extreme storms, are drowning beaches, eroding bluffs, flooding homes and businesses, and damaging roads and other essential public infrastructure, according to the report.

Between now and 2050 is a critical time for planning, said the researchers, and the new findings are intended to help state and local officials make "science-based decisions" for the future and look for ways to protect coastal communities and infrastructure.