Rising greenhouse gases may lead to another mass extinction of marine life

A new study has warned that the rapidly increasing levels of greenhouse gases in our oceans could lead to another mass extinction of marine life that happened during prehistoric times.

Prof Martin Kennedy from the University of Adelaide and Prof Thomas Wagner from Newcastle University, UK, have been studying 'greenhouse oceans' - those that have been depleted of oxygen, suffering increases in carbon dioxide and temperature.

Using core samples drilled from the ocean bed off the coast of western Africa, the geologists studied layers of sediment from the Late Cretaceous Period (85 million years ago) across a 400,000-year time span.

They found a significant amount of organic material - marine life - buried within deoxygenated layers of the sediment.

Wagner said the results of their research have relevance for our modern world.

"We know that 'dead zones' are rapidly growing in size and number in seas and oceans across the globe. These are areas of water that are lacking in oxygen and are suffering from increases of CO2, rising temperatures, nutrient run-off from agriculture and other factors," he said.

Kennedy said that the doubling of the amount of carbon dioxide in our atmosphere over the past 50 years is "like hitting our ecosystem with a sledge-hammer" compared to the very small changes in incoming solar energy which was capable of triggering these events in the past.

"This could have a catastrophic, profound impact on the sustainability of life in our oceans, which in turn is likely to impact on the sustainability of life for many land-based species, including humankind," he added.

The study was published in the Proceedings of the National Academy of Sciences (PNAS).