Melting icebergs in Antarctica can trigger the chain reaction to the new ice age

The Antarctic icebergs that are gradually melting further and further away from the frozen continent could be the trigger that throws the Earth into a new ice age, the study shows.

Researchers at Cardiff University have reconstructed past climatic conditions and identified tiny fragments of Antarctic rocks that fell into the open ocean as part of a study designed to understand how ice ages begin.

The cycles of the ice age of the last 1.6 million years have been punctuated by periodic changes in the Earth’s solar orbit – changing how much solar radiation reaches the surface.

However, before this study, little was known about how changes in solar energy from small changes in orbit could change the Earth’s climate so dramatically.

They found that the melting of the icebergs was gradually moving with fresh water from the southern Atlantic Ocean by melting further from Antarctica – causing a change in ocean circulation and sinking the planet in a cold period – triggering an ice age.

The impact of man-made CO2 emissions could make the Southern Ocean too hot to reach the Antarctic icebergs, ending the 1.6 million-year cycle of the ice age since the icebergs melted, the study’s authors warned.

In their study, the team proposes that when the Earth’s orbit around the Sun is in place, the Antarctic icebergs begin to melt further and further away from Antarctica.

This results in huge volumes of freshwater moving from the South Ocean and the Atlantic Ocean.

As the Southern Ocean becomes saltier and the North Atlantic becomes fresher, patterns of large-scale ocean circulation begin to change dramatically, releasing CO2 from the atmosphere and reducing the so-called greenhouse effect.

In turn, this pushes the Earth into ice age conditions, according to the team, which reconstructed past climatic conditions, including finding tiny fragments of Antarctic rocks that fell into the open ocean by melting icebergs.

The rock fragments were obtained from sediments recovered by the International Ocean Discovery Program (IODP), which represents 1.6 million years of history.

The study found that these deposits, known as ice debris, appear to constantly lead to changes in the deep ocean circulation, reconstituted from the chemistry of small deep fossils called foraminifera.

The team also used new simulations of the climate model to test its hypothesis, finding that huge volumes of fresh water could be moved by icebergs.

The study’s lead author, Aidan Starr, said they were amazed to find that the link between the melting iceberg and ocean circulation was present at the beginning of each ice age in the last 1.6 million years.

“Such a major role for the South Ocean and Antarctica in the global climate has been speculated, but it was very interesting to see it so clearly in geological evidence,” he said.

Professor Ian Hall, co-author of the study and co-scientist of the IODP Expedition in Cardiff, said the results provided a “missing link” in the history of the ice age.

Over the last three million years, the Earth has regularly plunged under ice conditions, but is now in an interglacial period in which temperatures are warmer.

However, it may not be repeated in the same way, due to the impact of man-made CO2 emissions that are warming the world.

Researchers suggest that the natural rhythm of ice age cycles could be disrupted, as the Southern Ocean will likely become too hot for Antarctic icebergs to travel far enough to trigger changes in ocean circulation needed to start the ice age.

Professor Hall believes that the results can be used to understand how our climate can respond to anthropogenic climate change in the future.

“Also, as we observe an increase in mass loss from the Antarctic continent and iceberg activity in the South Ocean, resulting from warming associated with current human greenhouse gas emissions,” Hall said.

“Our study highlights the importance of understanding iceberg trajectories and melting patterns in developing the most robust predictions of their future impact on ocean circulation and climate,” he said.

Professor Grant Bigg, from the Department of Geography at the University of Sheffield, who helped simulate the iceberg model, said it was an innovative modeling of climate models.

Its addition was crucial in “identifying and supporting the hypothesis of ice debris from the impact of the melting water of the Antarctic iceberg, which leads to the onset of the glacial cycle.”

The findings were published in the journal Nature.