New research from the University of Sydney details how massive carbonate formations have helped regulate the world’s ocean’s temperatures over the last 120 million years, and how climate change could possibly result in the release of their stored carbon into the atmosphere.
The team of scientists from the university’s School of Geosciences have modelled how carbonate accumulation from “marine snow” in oceans have absorbed carbon dioxide over millennia and have been a key player in regulating the planet’s temperature.
“Marine snow is the falling debris of dead organisms in the ocean, such as plankton and algae,” said the study’s lead author, Dr Adriana Dutkiewicz.
“The deep ocean floor is covered with the remains of these tiny sea creatures. They produce more than 25 percent of the oxygen we breathe and form the Earth’s largest carbon sink. When organic particles fall from the surface ocean to the seafloor, a small but significant proportion of atmospheric carbon is stored away.”
The study, published in Geology, also provides a snapshot into the world’s ocean’s ability to store carbon dioxide.
When compacted over millions of years, these marine snow deposits become carbonate structures, such as the White Cliffs of Dover and similar structures along England’s south coast. These chalk cliffs and their related structures under the ocean act as millennia-old carbon capture devices.
“Deep-sea carbonates represent a huge volume, so even small changes in the sequestration of carbonate carbon into this enormous sink are quite important for understanding net changes in atmospheric carbon dioxide and climate,” Dr Dutkiewicz said.
Her team found that the amount of carbon stored in carbonate layers on the seafloor has increased tremendously over time. About 80 million years ago, only one megatonne of carbon ended up in carbonate layers annually, growing to about 30 megatonnes about 35 million years ago and 200 megatonnes today.