A chemical analysis of sediment cores from the North Pacific Ocean shows a consistent pairing of volcanic ash and hypoxia, an interval of low oceanic oxygen spanning thousands of years, during times of rapid climate warming at the end of the last age glacial, new research shows.
Understanding the relationship between volcanic activity, hypoxia and ice melting due to warming temperatures during the last ice age, which ended about 18,000 years ago, raises important questions about what might happen when the planet it’s getting hot today
“It is currently unknown whether volcanic eruptions will increase as the climate warms,” said the study’s lead author, Jianghui Du of ETH Zurich in Switzerland, who conducted the research as a student from the College of Earth, Ocean and Oregon State University. Atmospheric Sciences.
“But we know that the remaining glaciers of the Pacific Ring of Fire volcanoes are melting rapidly, and it will be important to include this ice loss in predictions of future eruptions, which would be risky for populated regions and could also make emergent hypoxic. worst dead zones in the North Pacific.”
The study was published today in the journal Nature. The findings point to a systematic relationship between climate, glacier retreat, volcanic activity, biological productivity and ocean deoxygenation, said Oregon State oceanographer and paleoclimatologist and co-author Alan Mix of the document.
“These amazing links between parts of the Earth that we normally think of as separate highlight how interconnected the whole system really is,” he said. “Resolving environmental problems, such as those we face in the ongoing climate crisis, requires us to look with an open mind at the whole linked system and not just isolated parts.”
The volcanic region of the Pacific Ocean is known as the Ring of Fire in part because it is one of the most active tectonic and volcanic regions in the world.
The timing of the volcanic events relative to the retreat of the Cordillera ice sheet, which once covered large portions of western North America, suggests that rapid melting of the ice covering the region’s volcanoes induced increased volcanic activity, Mix said.
“The ice cover of volcanoes is like a cork in a champagne bottle. Remove the frozen cork and boom, eruptions begin,” he said.
Previous research had shown a few layers of ash in the region’s sediments, but Du’s chemical study, using deep-water sediment cores from the Gulf of Alaska, revealed more traces of ash that were not visible in the eye
Du cataloged and compared volcanic eruptions from areas that were ice-covered with those areas that were not ice-covered during the last ice age.
“We found a different pattern of many eruptions during warming and ice retreat in areas where the glaciers used to be, and much less change in the frequency of eruptions outside the ice-covered area, especially in the west of North America,” Du said. “This provides strong evidence of volcanic response to warming and ice retreat.”
Chemical fingerprints also showed a consistent pairing of volcanic ash and hypoxic events. The increase in volcanic ash likely fueled oceanic productivity that ultimately created low-oxygen conditions.
Texas A&M University co-authors Christina Belanger and Sharon, who use only one name, examined a species of seafloor organisms called foraminifera and found that they closely followed the influx of volcanic ash from the Gulf of Alaska . These organisms thrive under highly productive waters and can tolerate low oxygen conditions.
“Volcanic ash includes important nutrients for plankton, especially iron,” said co-author Brian Haley, a research professor at Oregon State.
“When ash reaches the ocean, phytoplankton gobble up this iron and flourish. This fertilization effect underscores a practical application of our work. Some have proposed fertilizing the North Pacific with iron to capture excess carbon dioxide carbon in the atmosphere,” he said. “We show that the real world has effectively performed this experiment in the past with volcanic iron, and the fertilization effect works and exports carbon into the deep sea. This is good news. But there are some dangerous consequences because when this excess organic matter breaks down as it falls into the ocean depths, consuming oxygen and creating dead zones.”
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