New Zealand's Iron-Rich Dust May Have Contributed to Earth's Last Ice Age

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New Zealand is rich in dust infused with iron which researchers said can help explain how the Earth cooled after the last Ice Age. Scientists travelled to New Zealand's Southern Alps in an expedition to gather dust samples and study their link to Earth's last Ice Age which happened approximately 22,000 years ago.

The dust in New Zealand was not the only reason for the Ice Age but it has more likely contributed to cool the Earth's temperatures, according to Bess Koffman, a researcher at the Lamont-Doherty Earth Observatory at Columbia University.

Ms Koffman told Live Science that the iron-rich dust in New Zealand usually increases when there are changes in climate. Researchers think that the dust is an "important driver" in the Earth's climate system. They found ice cores thousands of years old and marine sediments believed to be four million years old. The ice cores and sediments contained layers of iron-rich dust which correlates with periods of cooling.

How the dust cools the Earth

Iron-rich dust is associated with cooler temperatures based through growing plant-like organisms known as phytoplankton. According to scientists, large quantities of iron-rich dust can be found around in the world in pieces of broken-down rocks.

When the dust becomes loose and dry, it can easily travel and carried by winds into the atmosphere before settling on land or the open sea. Once in the ocean, the dust helps fertilise the phytoplankton which gets carbon dioxide from the atmosphere during photosynthesis.

When the plant-like organisms die, they sink to the bottom of the seafloor and bring with them huge amounts of carbon dioxide. This results in the gradual cooling of the climate.

Scientists originally thought that Australia may have been the most significant source of dust to the Southern Ocean in the last Ice Age. However, Ms Koffman's team thinks the abundant glaciers in New Zealand may have had a dustier landmass than the continent of Australia.

According to Ms Koffman, Australia was relatively wet in the last Ice Age compared to New Zealand which contained more iron-rich dust that would fertilise the marine phytoplankton.

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