By: Nour Hany

In a new study, scientists investigate the missing link in the process that leads to an ice age on Earth. In their research, the group of scientists examined a rock archive that goes back to 1.6 million years, to find that melting icebergs in the Antarctic may have triggered some chain reactions that caused previous ice ages.

Ice age cycles have always been known to be linked to periodic changes in the Earth's orbit of the Sun; this in turn, “changes the amount of solar radiation that reaches the Earth’s surface”. However, the mystery here lies in how such small variations in solar energy lead to such dramatic changes in our planet’s climate.

The study shows that Antarctic icebergs begin to melt further and further away from Antarctica when the Earth’s orbit around the Sun is just right, which results in “shifting huge volumes of freshwater away from the Southern Ocean and into the Atlantic Ocean”. The North Atlantic gets fresher and the Southern Ocean gets saltier, which makes “large-scale ocean circulation patterns begin to dramatically change, pulling CO2 out of the atmosphere and reducing the so-called greenhouse effect”. All these factors lead the Earth to go into ice age conditions.

Multiple techniques were used as part of the study to reconstruct past climate conditions; these included “identifying tiny fragments of Antarctic rock dropped in the open ocean by melting icebergs”. “Our results provide the missing link into how Antarctica and the Southern Ocean responded to the natural rhythms of the climate system associated with our orbit around the Sun”, said Professor Ian Hall, The School of Earth and Environmental Sciences.

Moreover, the team used new climate model stimulations in order to test their theories, and they found out that the icebergs could actually move huge volumes of freshwater. Professor Hall also added: “Likewise, as we observe an increase in the mass loss from the Antarctic continent and iceberg activity in the Southern Ocean, resulting from warming associated with current human greenhouse-gas emissions, our study emphasizes the importance of understanding iceberg trajectories and melt patterns in developing the most robust predictions of their future impact on ocean circulation and climate”.

“The groundbreaking modelling of icebergs within the climate model is crucial for identifying and supporting the ice-rafted debris hypothesis of Antarctic iceberg meltwater impacts, which are leading glacial cycle onsets”, said Professor Grant Bigg, from the University of Sheffield’s Department of Geography, who contributed to the iceberg model simulations.

References

• www.azocleantech.com
• www.scitechdaily.com