Herbarium records collected in Australia since the 1940s suggest up to 25 percent of temperate seaweed species living there could be headed to extinction, researchers at the University of Western Australia said.
"Our findings add an important piece in the puzzle that is determining the global impacts of climate change," Thomas Wernberg said.
The findings in Australia, published in the journal Current Biology, represent two of the major global oceans, the Indian and Pacific, Wernberg said.
"We found that temperate seaweed communities have changed over the past 50 years to become increasingly subtropical, and that many temperate species have retreated south towards the Australian south coast.
"We estimated that projected ocean warming could lead to several hundred species retracting south and beyond the edge of the Australian continent, where they will have no suitable habitat and may therefore go extinct."
This could have cascading effects across marine ecosystems, Wernberg said, as seaweeds are the "trees of the ocean," providing food, shelter and habitat to a diversity of other species.