Greenland Ice Sheet Platinum Spike: New Research Points to Icelandic Volcanic Origin, Not Meteorite Impact

Decades-Long Debate on Greenland's Platinum Anomaly

A significant platinum spike discovered in the Greenland Ice Sheet Project (GISP2) ice core, dating back approximately 12,800 years ago, has been a subject of intense scientific debate. This anomaly broadly coincided with the onset of the Younger Dryas Event (YDE), a period of abrupt cooling that lasted from about 12,870 to 11,700 years ago. Initially, the unusual geochemical signature, characterized by high platinum but low iridium levels, led many researchers to hypothesize an extraterrestrial origin, suggesting a meteorite or comet impact as the source.

Challenging the Extraterrestrial Impact Hypothesis

The previous hypothesis posited that an impact event, possibly involving an unusual iron meteorite, could have deposited the platinum and potentially triggered the Younger Dryas cooling. However, the specific ratio of platinum to iridium in the ice core did not align with typical meteorite compositions. New research, published in PLOS One on September 18, 2025, offers a compelling alternative, suggesting a terrestrial origin for this platinum anomaly.

Volcanic Fissure Eruptions as the Likely Source

The recent study proposes that the platinum spike represents highly fractionated material from an Icelandic subglacial or submarine fissure eruption. A key finding supporting this volcanic origin is the duration of the platinum spike, which lasted for 14 years. This prolonged event is more consistent with a fissure eruption than an instantaneous impact. Researchers ruled out the German Laacher See volcanic eruption as the source, as its pumices contain virtually no platinum. Instead, the chemical signature in the Greenland ice core closely matches volcanic gas condensates, particularly those from submarine volcanic complexes. The interaction of submarine or subglacial eruptions with water can strip away sulfur compounds while concentrating elements like platinum in volcanic gases, which could then travel to Greenland and be deposited on the ice sheet. Historical Icelandic eruptions, such as the 8th-century Katla and 10th-century Eldgjá, have previously caused spikes in other heavy metals in Greenland ice cores, further supporting this mechanism.

Revisiting the Younger Dryas Connection

Crucially, the new research also refined the timing of the platinum spike relative to the Younger Dryas Event. It found that the platinum anomaly occurred approximately 45 years after the Younger Dryas began, indicating that it was unlikely to have been the trigger for the cold period. While the platinum spike's role in initiating the Younger Dryas is now questioned, the research highlights that a separate, massive volcanic sulfate spike in multiple ice cores *did* coincide precisely with the onset of the Younger Dryas 12,870 years ago. This suggests that a different volcanic event, possibly the Laacher See eruption or another unknown volcano, was the probable trigger for the significant cooling. Understanding these past climate triggers, whether volcanic or extraterrestrial, remains vital for anticipating future climate changes.