Icebergs in Antarctica, which are gradually melting farther and farther away from the frozen continent, may be the reason that plunges the Earth into a new ice age, a study finds.
Researchers at the University of Cardiff have restored past climatic conditions and identified small fragments of Antarctic rock released into the open ocean as part of a study designed to understand how the ice ages began.
The cycles of the ice age over the last 1.6 million years have undergone periodic changes in the Earth’s Earth’s orbit – a change in how much solar radiation reaches the surface.
Prior to this study, however, little was known about how changes in solar energy as a result of small changes in orbit could drastically change the Earth̵
They found that melting icebergs gradually shifted freshwater from the South to the Atlantic Ocean, melting further from Antarctica – causing a change in ocean circulation and sinking the planet in cold weather – causing an ice age.
The effects of man-made CO2 emissions could make the Southern Ocean too warm to reach Antarctic icebergs, ending this 1.6 million-year cycle of ice ages that began with melting icebergs, the study’s authors warned.
Icebergs in Antarctica, which are gradually melting farther and farther away from the frozen continent, may be the reason that plunges the Earth into a new ice age, a study finds. Spare image
The team found that Antarctic icebergs gradually remained unmelted further north during certain changes in the Sun’s Earth’s orbit – a reduction in solar energy coming to the surface.
In their study, the team suggests that when the Earth’s orbit around the Sun is accurate, Antarctic icebergs begin to melt farther and farther away from Antarctica.
This leads to the transfer of huge amounts of fresh water from the Southern Ocean to the Atlantic Ocean.
As the Southern Ocean becomes saltier and the North Atlantic becomes fresher, large-scale ocean circulation patterns begin to change dramatically, extracting CO2 from the atmosphere and reducing the so-called greenhouse effect.
This in turn pushes the Earth into an ice age, according to the team, which is reconstructing past climates, including finding small fragments of Antarctic rock released into the open ocean by melting icebergs.
The rock fragments were obtained from sediments extracted from 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 be constantly leading to changes in deep ocean circulation, reconstructed by the chemistry of small deep-sea fossils called foraminifera.
The team identified small fragments of Antarctic rock that were deposited in the open ocean by melting icebergs to track changes in salt and freshwater over time.
The team also used new simulations of climate models to test their 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 iceberg melting and ocean circulation had been present during the onset of each ice age for the past 1.6 million years.
“Such a leading role for the South Ocean and Antarctica in the global climate is speculated, but seeing it so clearly in the geological evidence was very exciting,” he said.
Professor Ian Hall, co-author of the study and co-scientist of the IODP expedition from Cardiff, said the results provided a “missing link” in the history of the ice age.
Antarctic icebergs travel to the Southern Ocean without melting and transporting fresh water from that ocean to the Atlantic Ocean, causing changes in ocean circulation and cooler periods.
For the past three million years, the Earth has been regularly exposed to ice ages, but is currently in the interglacial period, where temperatures are warmer.
However, it may not be the same due to the impact of man-made CO2 emissions, which are warming the world.
Researchers suggest that the natural rhythm of glacial cycles may be disrupted, as the Southern Ocean is likely to become too warm for Antarctic icebergs to travel far enough to cause the changes in ocean circulation needed to begin the ice age.
Professor Hall believes the results can be used to understand how our climate may respond to anthropogenic climate change in the future.
“In the same way as we are seeing an increase in mass losses from the Antarctic continent and iceberg activity in the Southern Ocean as a result of warming associated with current human greenhouse gas emissions,” Hall said.
“Our study emphasizes the importance of understanding iceberg trajectories and melting patterns in developing the most reliable predictions for their future impact on ocean circulation and climate,” he said.
Professor Grant Big of the Department of Geography at the University of Sheffield, who contributed to the simulations of the iceberg model, said it was an innovative modeling within climate models.
Its addition is crucial for “identifying and maintaining the hypothesis of scattered ice ruins for the effects of the Antarctic iceberg from molten water, which are leading at the beginning of the ice cycle”.
The findings are published in the journal Nature.
ATLANTIC OCEAN CIRCLES PLAY A MAIN ROLE IN REGULATING GLOBAL CLIMATE
In terms of global climate regulation, circulation in the Atlantic plays a key role.
This is due to the ever-moving deep-water circulation system, often called the Global Ocean Conveyor, which sends warm, salty water from the Persian Gulf to the North Atlantic, where it emits heat into the atmosphere and warms Western Europe.
The cooler water then sinks to great depths and travels all the way to Antarctica and eventually circulates back to the Gulf Stream.
In terms of global climate regulation, circulation in the Atlantic plays a key role
This movement is fueled by thermohaline currents – a combination of temperature and salt.
It takes 1,000 years for water to complete its continuous journey around the world.
Researchers believe that when the North Atlantic began to warm toward the end of the Little Ice Age, freshwater disrupted a system called the Atlantic Meridian Circulatory Circulation (AMOC).
Arctic sea ice and ice sheets and glaciers around the Arctic began to melt, forming a huge natural freshwater tap gushing into the North Atlantic.
This huge influx of fresh water dilutes surface seawater, making it lighter and less able to sink deep, slowing down the AMOC system.
Researchers have found that AMOC has been weakening faster than 1950 in response to recent global warming.