. | . |
Ancient ocean oxygen levels associated with changing atmospheric carbon dioxide by Staff Writers College Station TX (SPX) May 21, 2020
Why do carbon dioxide levels in the atmosphere wax and wane in conjunction with the warm and cold periods of Earth's past? Scientists have been trying to answer this question for many years, and thanks to chemical clues left in sediment cores extracted from deep in the ocean floor, they are starting to put together the pieces of that puzzle. Recent research suggests that there was enhanced storage of respired carbon in the deep ocean when levels of atmospheric carbon dioxide concentrations were lower than today's levels. But new research led by a Texas A and M University scientist has reached back even further, for the first time revealing insights into atmospheric carbon dioxide levels in the 50,000 years before the last ice age. "One of the biggest unknowns about past climate is the cause of atmospheric carbon dioxide variability over global warm-cold cycles," said Franco Marcantonio, lead author of the study and professor and Jane and Ken R. Williams '45 Chair in the Department of Geology and Geophysics at Texas A and M. "Here we investigated the 'how' of varying carbon dioxide with the 'where' - namely, the Eastern Equatorial Pacific Ocean, which is an important region of the world ocean where, today, significant carbon dioxide is exhaled into the atmosphere and the greatest rates phytoplankton growth are found." The National Science Foundation-funded research was recently published in Scientific Reports, a Nature Research journal. To examine ancient carbon dioxide levels, Marcantonio and a team of researchers analyzed an ocean floor sediment core extracted from the deep Eastern Equatorial Pacific Ocean. The 10-meter long core spans about 180,000 years, and the chemistry of the layers of sediment provide scientists with a window into past climates. The chemical measurements they make serve as a proxy for oxygen levels of the deep sea. Measuring minute traces of uranium and thorium isotopes, the team was able to associate periods of increased storage of respired carbon (and low deep-sea oxygen levels) with periods of decreased global atmospheric carbon dioxide levels during the past 70,000 years. "By comparing our high-resolution sediment record of deep-sea oxygenation in the Eastern Equatorial Pacific with other areas of the Pacific and Southern Ocean, we find that the Pacific Ocean, like the Southern Ocean, is a location for deep-ocean respired carbon storage during periods of decreased global atmospheric CO2 concentrations," he said. "Importantly, we put constraints on the location in the water column of the extent of the respired stored carbon pool during cold periods. "Understanding the past dynamics of Earth's carbon cycle is of fundamental importance to informing and guiding societal policy-making in a warming world with increasing levels of atmospheric carbon dioxide." Co-authors of the study were Ryan Hostak, a former Texas A and M graduate student who earned his master's degree in geology in 2019; Jennifer E. Hertzberg, who received her Ph.D. in oceanography from Texas A and M in 2015 and is now a postdoctoral researcher in the Department of Earth, Ocean and Atmospheric Sciences at Old Dominion University; and Matthew W. Schmidt, associate professor of Ocean, Earth and Atmospheric Sciences at Old Dominion. Marcantonio and his colleagues designed the study, he and Hostak performed the isotope analyses, and the team interpreted the data. "By performing similar studies in sediment covering a wider swath of the deep Pacific Ocean, we'll be able to spatially map the extent of this past deep pool of respired carbon," Marcantonio said, looking forward to future research.
Ancient rocks show high oxygen levels on Earth 2 billion years ago Edmonton, Canada (SPX) May 13, 2020 Earth may have been far more oxygen-rich early in its history than previously thought, setting the stage for the evolution of complex life, according to new research by scientists at the University of Alberta and the University of Tartu in Estonia. The study provides evidence for elevated oxygen levels 2 billion years ago and flies in the face of previously accepted models. The international team of researchers, led by UAlberta scientists, studied a Russian drill core containing shungite - a uniqu ... read more
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |