The study says the ice age could help predict the oceans’ response to global warming
This article has been reviewed in accordance with Science
Credit: CC0 public domain
Credit: CC0 public domain
A team of scientists led by a Tulane University oceanographer has discovered that sediments deep beneath the ocean floor reveal a way to measure the level of oxygen in the ocean and its connections to carbon dioxide in Earth’s atmosphere during the last ice age, which ended more than 11,000 years ago. since.
Results published in Advancement of sciencehelps explain the role the oceans played in past glacier melting cycles and could improve predictions about how ocean carbon cycles will respond to global warming.
The oceans adjust atmospheric carbon dioxide2 As ice ages transition to warmer climates by releasing greenhouse gases from carbon stored deep in the oceans. The research demonstrates a striking relationship between oxygen contents in the global oceans and carbon dioxide in the atmosphere2 From the last ice age to today, and how deep-sea carbon emissions could rise as the climate warms.
“The research reveals the important role of the Southern Ocean in controlling the global ocean oxygen reservoir and carbon storage,” said Yi Wang, lead researcher and assistant professor of Earth and Environmental Sciences in Tulane University’s College of Science and Engineering. Wang specializes in marine biochemistry and paleoceanography.
“This will have implications for understanding how the ocean, especially the Southern Ocean, dynamically affects atmospheric carbon dioxide2 In the future,” she said.
Wang conducted the study with colleagues from Woods Hole Oceanographic Institution, the world’s leading non-profit organization specializing in ocean research, exploration and education. She worked at the institute before joining Tulane in 2023.
The team analyzed seafloor sediments collected from the Arabian Sea to reconstruct average oxygen levels in the global oceans thousands of years ago. They precisely measured isotopes of the metal thallium trapped in the sediment, indicating the amount of dissolved oxygen in the global ocean at the time the sediment formed.
“The study of these mineral isotopes on glacial transitions between ice ages had not been considered before, and these measurements allowed us to essentially recreate the past,” Wang said.
Thallium isotope ratios showed that the global ocean generally lost oxygen during the last ice age compared to the current warmer interglacial period. Their study revealed that oxygen in the oceans declined globally for a millennium during sudden warming in the Northern Hemisphere, while the ocean gained more oxygen when sudden cooling occurred during the transition from the last ice age to today. The researchers attributed the observed changes in ocean oxygen to Southern Ocean processes.
“This study is the first to provide an average picture of how oxygen content in the global oceans evolved as Earth transitioned from the last glacial period to a warmer climate over the past 10,000 years,” said WHOI associate scientist Sonny Nielsen and his team. – Author of the research.
“This new data is a really big deal because it shows that the Southern Ocean plays a crucial role in modifying atmospheric carbon dioxide.2. Given that high latitude regions are most affected by human-induced climate change, it is alarming that these regions also have a significant impact on atmospheric carbon dioxide.2 in the first place.”
Yi Wang et al., Global ocean oxygen controlled by the Southern Ocean during recent deglaciation, Advancement of science (2024). doi: 10.1126/sciadv.adk2506. www.science.org/doi/10.1126/sciadv.adk2506
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