New research indicates that greenhouse gases cause conditions similar to those that led to a mass extinction in the oceans millions of years ago.
Two geologists, professor Martin Kennedy from the University of Adelaide in south Australia and professor Thomas Wagner from Newcastle University in the U.K., studied core samples drilled off the coast of west Africa.
In particular, they examined layers of sediment from the Late Cretaceous Period (85 million years ago) across a 400,000-year timespan and found a significant amount of organic material — marine life — buried within deoxygenated layers of the sediment.
The scientists drew parallels between the deoxygenated layers of sentiment from millions of years ago and deoxygenated conditions in the oceans of today.
"We know that 'dead zones' are rapidly growing in size and number in seas and oceans across the globe," Wagner said in a news release. "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."
While expressing concern, the scientists say the geological record indicates that natural processes eventually respond to the greenhouse gas conditions, and oxygen concentration levels in the oceans seems to improve. In time, marine life returns as well.
The natural processes include soil-based minerals from land coming into the ocean to help collect and bury excess dissolved organic matter. The burial of such material contributes to CO2 removal from the atmosphere and leads to a cooling of the planet and oceans.
"This is nature's solution to the greenhouse effect and it could offer a possible solution for us," said Wagner. "If we are able to learn more about this effect and its feedbacks, we may be able to manage it, and reduce the present rate of warming threatening our oceans."
Download the research report: "Clay mineral continental amplifier for marine carbon sequestration in a greenhouse ocean"