Ancient dust from the depths of the ocean can help keep the last ice age cool


The sea floor of the South Pacific Ocean has traces of ancient dust, which probably changed the very climate of the Earth, and new research suggests that it has now come all the way down to Argentina’s ice age glaciers.

Nearly 20,000 years ago these micro-minerals surrounded by strong winds would have circulated almost the entire world before coming to rest in the mid-latitudes of the Pacific.

Crucially, they carried a nutrient that could explain the period of global cooling. That component was of iron.

Iron is an important nutrient for microalgae in our oceans, known as phytoplankton, and these organisms form a fundamental part of the Earth’s climate.

This is because phytoplankton absorbs carbon during photosynthesis, leading to the storage of atmospheric CO2 in our oceans and global cooling. They may represent the “largest organic carbon sequestration system on the planet”.

Today, iron still helps fertilize our oceans, but during the climax of Earth’s last ice age, a lot of iron-rich dust was detected during seasonal glacier melting, and it blew into the ocean at a much higher rate was given.

Tauran Struve, a geologist at the University of Oldenburg in Germany, says that this extra iron reduced phytoplankton again as CO2 levels in the atmosphere helped to explain “how the Earth could have been so cold at that time”.

For example, some scientists think that iron fertilization may be a useful way to increase the carbon sink of our oceans and help cool our planet in the future.

But such geoengineering is a risky and controversial strategy, and the results of this new study only indicate how much dust will be needed for a large enough effect.

Today, since the Industrial Revolution, CO2 levels in human emissions have increased from 280 to about 415 ppm (per million) – a boom that is far above natural levels.

During the last ice age, however, previous models have confirmed that iron-bearing dust was responsible for pulling atmospheric CO2 below about 40 ppm.

There is about half of the natural diversity between that ice age and the following inter-period, and not even a quarter of our own emissions.

Nevertheless, scientists are determined to learn more about this complex reaction system in the hope that it may one day improve our climate model or help us capture more environmental carbon.

Analyzing 18 sediment cores from the South Pacific Ocean between Antarctica, New Zealand and Chile, the new study has compared ancient dust chemical fingerprints from many different continents to geological data.

Finally, the findings suggest that up to 80 percent of iron-rich dust has now come from northwest Argentina – and perhaps has come a long way, covering about 20,000 kilometers (12,400 mi) of strong winds during the last days. was traveling. Major ice age

This is a unique and interesting discovery, because today, dust input from Australia’s rivers and lakes dominates the entire study area.

Even in the past, Patagonia is generally regarded as a major source of far-flung, ancient dust, not further north than in central-South America.

“[W]Strowe says that E was surprised to learn that the dust sources and transportation routes were completely different from today and even different from what we expected.

“Global warming has changed winds and environmental conditions in source areas.”

Even small as dust can have global consequences. Thirty years later when we first discovered its effect on the climate system, we are still learning more about these micro-minerals, including where they came from.

The study was published in Nature communication.

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