Iron and Ice
How Iron Cooled the Earth 20,000 Years Ago
Ancient, iron-rich dust played a role in global cooling during the last ice age. This theory is based on studying 18 sediment cores across the South Pacific Ocean between Chile, Antarctica, and New Zealand. The work identifies iron-bearing dust layers trapped in marine sediments. These dust layers were deposited about 20,000 years ago, during the Late Wisconsinan glaciation. This period corresponded to the last glacial maximum — the coldest part of the glacial cycle.
The iron-bearing dust, which contributed to global cooling, came from the Patagonia region of South America. This area has the environmental preconditions to produce dust rich in iron: high elevation, arid conditions, fluvial activity to move sediments through streams and rivers, and high levels of glacial activity during glacial intervals.
The right environment
High elevations and an arid environment create conditions where dry dust is exposed to intense winds, allowing the particles to be lifted and entrained into global wind currents. This situation is ideal for transporting Patagonian dust on the westerly winds circling the globe around Antarctica. Sediments and dust picked up in South American during the last ice age traveled eastward on a circumpolar journey, eventually settling out over the…
