Melting icebergs are the key to the sequence of an ice age, scientists find

Scientists claim to have found the ‘missing link’ in the process leading to an ice age on Earth.

Melting icebergs in Antarctica are key, says the team at Cardiff University, which is causing a series of chain reactions that plunge the earth into a long period of cold temperatures.

The findings are in Earth from an international consortium of scientists from universities around the world.

It has long been known that ice age cycles continue through periodic changes to the earth’s orbit of the sun, which then changes the amount of solar radiation that reaches the earth’s surface.

So far, however, it has been a mystery how small variations in solar energy can cause such dramatic shifts in the Earth’s climate.

In their study, the team suggests that when the Earth’s orbit around the sun is just right, Antarctic icebergs begin to melt further and further from Antarctica, shifting large amounts of fresh water from the Southern Ocean and into the Atlantic Ocean.

As the Southern Ocean becomes saltier and the North Atlantic area becomes fresh, large-scale circulation patterns begin to change dramatically and attract CO₂ outside the atmosphere and reduce the so-called greenhouse effect.

It pushes the earth back into ice age conditions.

As part of their study, the scientists used several techniques to reconstruct the climatic conditions of the past, including identifying small fragments of Antarctic rock that had been deposited in the open ocean by melting icebergs.

The rock fragments were obtained from sediments recovered by the International Ocean Discovery Program (IODP) Expedition 361. It represents more than 1.6 million years of history and one of the longest detailed archives of Antarctic icebergs.

The study found that these deposits, known as Ice-Rafted Debris, apparently consistently lead to changes in deep ocean circulation, reconstructed from the chemistry of small deep-sea fossils called foraminifera.

The team also used new symptoms of climate models to test their hypothesis, and found that large amounts of fresh water could move through the icebergs.

Lead author of the study Aidan Starr, of Cardiff University’s School of Earth and Environmental Sciences, said: “We were surprised to discover that this backlog ratio was present at the start of each ice age for the past 1.6 million years. a leading role for the Southern Ocean and Antarctica in the world climate is speculated, but it was very exciting to see it in geological evidence.

Professor Ian Hall, co-author of the study and co-lead scientist of the IODP expedition, also of the School of Earth and Environmental Sciences, said: “Our results provide the missing link in how Antarctica and the Southern Ocean responded to the natural rhythms of the climate system associated with our orbit around the sun. ‘

For the past three million years, the Earth has frequently plunged into ice age conditions, but at present it is located within an interglacial period where the temperature is warmer.

Due to the rising global temperatures due to anthropogenic CO₂ emissions, the researchers suggest that the natural rhythm of the ice age cycles could be disrupted, as the Southern Ocean is likely to become too hot for the Antarctic icebergs to move far enough to cause the changes in ocean circulation needed to to develop an ice age.

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

‘As we see an increase in Antarctic continent mass loss and iceberg activity in the Southern Ocean due to the warming associated with current human greenhouse gas emissions, our study highlights the importance of understanding iceberg orbits and melting patterns in development. of the strongest predictions of their future impact on the circulation and climate of the ocean, ”he said.

Professor Grant Bigg of the Department of Geography at the University of Sheffield, who contributed to the symbols of the iceberg model, said: “The groundbreaking modeling of icebergs within the climate model is crucial to identifying and supporting the Antarctic ice floes hypothesis. iceberg meltwater impacts. which is the leading glacier cycle. ‘