The mass extinction of marine life in our oceans during prehistoric times is a warning that the Earth will see such an extinction again because of high levels of greenhouse gases, according to new research by geologists.
Professor Martin Kennedy from the University of Adelaide (School of Earth & Environmental Sciences) and Professor Thomas Wagner from Newcastle University (Civil Engineering and Geosciences) have been studying 'greenhouse oceans' oceans that have been depleted of oxygen and suffered from increases in carbon dioxide and temperature.
Using core samples drilled from the ocean bed off the coast of western Africa, the researchers studied layers of sediment from the Late Cretaceous Period (85 million years ago) across a 400,000-year timespan. They found a significant amount of organic material marine life buried within deoxygenated layers of the sediment.
"Our research points to a mass mortality in the oceans at a time when the Earth was going through a greenhouse effect, with high levels of carbon dioxide in the atmosphere, and rising temperatures, leading to a severe lack of oxygen (hypoxia) in the water that marine animals are dependent on," Professor Kennedy says.
"What's alarming to us as scientists is that there were only very slight natural changes that resulted in the onset of hypoxia in the deep ocean. This occurred relatively rapidly in periods of hundreds of years, or possibly even less not gradually over longer, geological time scales, which suggests that the Earth's oceans are in a much more delicate balance during greenhouse conditions than originally thought, and may respond in a more abrupt fashion to even subtle changes in temperature and CO2 levels than previously thought."
Professor Wagner says the results of their research, published in the Proceedings of the National Ac
|Contact: Martin Kennedy|
University of Adelaide