Ocean Floor Sediments Reflect Worlds Warmer Future

Recently a paleoceanographer, Alex Dickson, and his colleagues at The Open University in England have analyzed core sediment samples from the ocean floor. The Integrated Ocean Drilling Program, an ongoing international marine research project, gathered the samples.  The Paleocene-Eocene Thermal Maxim (PETM), which occurred approximately 55.9 million years ago was associated with rapid global warming, profound changes in ecosystem, and major perturbations in the carbon cycle. This caused changes in the ocean environment including animal migrations, ocean productivity, acidification and changes in the water cycle. Scientists analyzing seafloor sediment saw lower oxygen levels during this period. Lower oxygen levels caused by climate warming can have a negative impact on marine life, and scientists from the US and Europe have recorded an expansion in these deoxygenated zones over the past 50 years.  Researchers studying the oxygen poor sulfur rich sediment have found that the level of oxygen regulates a particular isotope called molybdenum. These particular isotopes adhere to manganese oxide through a process called absorption. This process can take hundreds of thousands of years. In low-oxygen environments this process is speeded up considerably. The composition of the isotopes in the sediment sample collected can give researchers an indication of the differing oxygen levels in the ocean thousands and millions of years ago. This is one of the first studies to experimentally validate the idea that warming during the PETM led to low oxygen levels in the ocean. These findings are critical to today’s research regarding climate change and its effects on the ocean environment.