Ancient Volcanoes Released Hidden Carbon, Warming Climate

An international team of geoscientists has identified ancient volcanic activity, as led by volcanologist Benjamin Black at Rutgers University-New Brunswick, that shed a light on Earth's past climate. The study stated that ancient volcanoes had kept on releasing large volumes of carbon dioxide (CO2) from deep within Earth long after their eruptions had ceased. This was dubbed "cryptic carbon" and contributed to warming periods during critical shifts in Earth's climate history.

It solved an old enigma on how Earth's climate remained warm for millions of years after the eruption of super-large volcanic eruptions, the most famous examples being at the end-Permian mass extinction event 252 million years ago-the largest biodiversity collapse known to mankind. Despite these Siberian eruptions' end, the climate continued to lag behind its new normal and took a bit more than 5 million years to recover-a time span which puzzled the minds of researchers for centuries. They discovered analogous characteristics in other episodes of high volcanic activity and wanted to know the processes at play.

This is according to research, which has been found through the chemical composition of ancient lava, computer modeling that simulates underground melting, and records from sedimentary rock. The scientists concluded that the CO2 emissions were released from magma deep within the Earth's crust and mantle, long after the surface eruptions had ended. Such "cryptic carbon" from the below-surface magma maintained continued climate warming, akin to volcanoes "releasing carbon from beyond the grave.".

These findings are important because they reveal a previously unknown source of CO2 that in the past has been a factor in the disruption of Earth's climate, which means that the natural control mechanisms of the planet could allow it to recover but only on geological timescales that stretch over hundreds of thousands to millions of years. Black notes that although ancient volcanic activity may help explain how climate can recover, it cannot explain current climate change, which is driven mainly by human-generated emissions. Today's volcanic activity emits only a small portion of the CO2 produced by humans.

But the study gives a glimpse of Earth's resilience. Knowing ancient volcanic CO2 emissions helps scientists understand how natural climate systems might respond to modern carbon release. Black stresses that the rare scale of past volcanism, which could cover vast areas in lava, happened millions of years ago and nothing like it is happening today. As one part of a broader multidecade research grant underwritten by the National Science Foundation to follow up additional investigation into the role of cryptic carbon in recovery from climate change, it continues to take samples, analyze them. Among them latest ones are glassy rocks from the Oregon Wallowa Mountains for more study of these elusive emissions.