At a Glance

Tidal wetlands in California and Oregon are particularly vulnerable to sea level rise.Researchers say nearly all salt marshes along West Coast will disappear by the turn of the century.The loss of West Coast salt marshes could have an ecological cascading effect on breeding and food systems for fish and birds.

Tidal wetlands along the West Coast, particularly those in California and Oregon, will disappear by the turn of the century as seas continue to rise, a new study says.

The U.S. Geological Survey and the University of California Los Angeles teamed up to study the impacts of rising seas on coastal salt marshes. Using established sea level rise predictions, the team evaluated 14 estuaries along the West Coast.

Their findings are not encouraging.

"Throughout the U.S. Pacific region, we found that , with resulting extensive loss of habitat," the researchers said in the study published Wednesday in Science Advances.

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Using higher-range sea-level rise expected, all high and middle marsh habitats were lost, the researchers reported in the study. When they used data at the lower-range sea-level rise, 83 percent of tidal wetlands transitioned to unvegetated habitats.

“The bottom line is, ,” Richard Ambrose, a UCLA professor of environmental health and co-author of the paper, said in a school press release. “Some will go away by 2050.”

The wetland area lost in models used by the researchers was greater in California and Oregon, with 100 percent of the marshes lost. Washingtonwould lose 68 percent of its tidal wetlandsby end of the century, according to the study.

The researchers note that sea level rise predictions may be conservative, so the scenario that eventually plays out may be far worse.

“It depends a lot on what we do now,” Ambrose said. “In part, it depends on whether we’re able to reduce our emissions and greenhouse gases to limit climate change over the next 50 or 100 years. It also depends on what will happen to the ice sheets in Antarctica and Greenland.”

Glen MacDonald, a UCLA distinguished professor of geography and another co-author of the paper, said theloss of the salt marshes would extend to other ecosystems.

“We could see an ecological cascading effect” on breeding and food systems for fish, birds and other organisms, MacDonald said. “If you erase an entire system, the effects are going to ripple upward to predators and downward to prey species. It is just startling.”

Typically, coastal marshland can adapt to rising seas by moving further inland, but the West Coast's rocky coastline and human development along the coast will prevent this process known as "transgression."

“Especially in SoCal, we’ve developed up to the edge of almost every marsh,” Ambrose said. “That limits what the marshes can do and how they can respond. It makes them much more vulnerable.”