Phosphorus spikes linked to ancient marine mass extinctions

Phosphorus spikes linked to ancient marine mass extinctions

Recent research has presented compelling evidence that transient increases in ocean phosphorus levels may have significantly influenced two of the most catastrophic marine extinctions in Earth's history. Led by Dr. Matthew Dodd of The University of Western Australia's School of Earth and Oceans, the study, published in Nature Communications, provides critical insights into how disruptions in nutrient cycles can destabilize global ecosystems, climate, and ocean chemistry.

The investigation focused on the Late Ordovician and Late Devonian mass extinctions, which occurred approximately 445 and 372 million years ago, resulting in the extinction of roughly 85% and 80% of marine species, respectively. "In contrast to several other major extinction events, both occurrences were characterized by global cooling instead of warming, which has led to ongoing debate regarding their underlying causes," Dr. Dodd noted.

To reconstruct ancient seawater phosphorus levels, the research team analyzed phosphorus concentrations in carbonate rocks from seven globally distributed rock sections, including notable reference locations such as Anticosti Island in Canada.

Findings indicated that brief but distinct pulses of phosphorus correlated with significant biodiversity decline, widespread ocean anoxia, and decreasing temperatures.

"Our research demonstrates that disruptions in the phosphorus cycle can lead to severe implications for climate and biodiversity," Dr. Dodd stated. "This is particularly relevant today, as human activities are once more modifying nutrient flows into the oceans; the geological record illustrates the profound consequences such changes can induce."

Additionally, the team employed biogeochemical modeling to evaluate whether surges in phosphorus could elicit the environmental changes documented in the geological record.

The modeling results revealed that increased marine phosphorus could enhance productivity, exacerbate anoxic conditions, and contribute to reductions in atmospheric carbon dioxide, collectively facilitating global cooling of approximately 5°C.

"What is particularly striking is that the ancient events we investigated seem to have been associated with phosphorus-driven cooling, not greenhouse gas-induced warming," Dr. Dodd remarked. "Today, we are accelerating climate change in the opposite direction through rapid carbon dioxide emissions, yet the key takeaway remains: significantly disrupting a major biogeochemical cycle can lead to environmental crises.

"Our findings offer one of the clearest connections between nutrient disruption in marine environments and ecological crises in the ancient world, simultaneously reminding us that alterations in nutrient cycling can yield extensive repercussions for ocean health and environmental stability."

Co-author Professor André Desrochers from the University of Ottawa emphasized that these findings underscore the intricate relationships between ocean chemistry, climate, and biodiversity during pivotal extinction events.

"Anticosti Island in Quebec presents one of the most comprehensive records of the Late Ordovician extinction," Professor Desrochers highlighted. "When combined with other global sections, it is instrumental in revealing the interconnected nature of Earth system processes during this critical period."

Publication details

Matthew S. Dodd et al, Recurring marine phosphorus spikes during major palaeozoic mass extinctions and climate change, Nature Communications (2026). DOI: 10.1038/s41467-026-70701-y