Massive volcanic eruptions have dramatically reshaped Earth’s landscape and climate throughout history. These colossal events, often associated with large igneous provinces (LIPs) – vast regions where magma surges to the surface – have left an indelible mark on our planet’s geological record. But a new study published in *Nature Geoscience* suggests that the impact of these volcanic behemoths extends far beyond the initial eruption itself.
The research introduces the concept of “cryptic carbon.” While previously, scientists focused primarily on CO2 released during the active eruption phase of LIPs, this groundbreaking work reveals a significant, previously overlooked source of greenhouse gas emissions. It posits that long after lava flows cease, carbon dioxide dissolved within underground magmas slowly escapes to the surface. This prolonged, insidious release, dubbed “cryptic carbon,” may have played a pivotal role in extended warming periods, delayed climate recovery, and devastating mass extinctions.
“There’s the potential for this gas release that’s not tied in a specific way to the generation of a lava flow,” explains Isabel Fendley, a geologist at Pennsylvania State University who was not involved in the study. This protracted CO2 release, she emphasizes, means our current understanding of gas emission events may be incomplete, lacking a crucial piece of the puzzle.
The scale of these volcanic events is staggering. Ben Black, the study’s lead author and a volcanologist at Rutgers University, paints a vivid picture: “We’re talking about volcanic events that can mobilize enough magma to cover the continental U.S. half a kilometer deep.” These aren’t isolated incidents; their immense scale profoundly influenced Earth’s climate, often coinciding with periods of significant environmental disruption and biological upheaval.
The Siberian Traps eruptions, 252 million years ago, provide a stark example. These eruptions coincided with the end-Permian mass extinction, also known as the Great Dying—an event that wiped out over 90% of marine species and 70% of terrestrial vertebrates. Intriguingly, even after the eruptions subsided, high temperatures and elevated CO2 levels persisted for approximately 5 million years. While weakened silicate weathering feedback has been proposed as a contributing factor, the new research suggests a more substantial explanation: the continued release of cryptic carbon.
Using sophisticated numerical models, Black and his colleagues demonstrated that CO2 emissions from surface eruptions alone cannot fully account for these prolonged warming periods. Their simulations reveal that the observed warming demands a sustained release of carbon dioxide well after the youngest volcanic rocks have cooled. Further simulations of magma movement through the Earth’s crust revealed the mechanism behind this cryptic release.
Initially, pressure builds within magma chambers until cracks in the crust form, allowing magma to reach the surface. However, over time, the magma heats the surrounding rock, making it more fluid. This reduces the ability to build up the pressure necessary for surface eruptions. Yet, as the magma rises and cools, dissolved CO2 gradually escapes, even without further surface eruptions. This is analogous to opening a soda bottle: the pressure reduction allows dissolved gas to form bubbles and escape.
This process, according to study co-author Tamsin Mather, a volcanologist at the University of Oxford, can continue for millions of years. The long-term release of cryptic carbon could explain the extended warming observed after LIP eruptions subsided, profoundly impacting biological recovery and potentially contributing to the severity of mass extinctions such as the end-Permian event.
The implications of this research extend beyond our understanding of past climate events. Mather highlights the relevance to contemporary climate change: “Large igneous provinces are one of the best analogues for carbon emission fluxes on the scale of human carbon emission fluxes, but they still don’t emit carbon as fast as we are right now.” By understanding how the planet recovered from similarly abrupt disruptions in the past, scientists can gain valuable insights into the potential impacts of anthropogenic emissions and guide strategies for mitigating future climate change. The discovery of cryptic carbon opens a new chapter in our understanding of Earth’s climate history and the long-lasting consequences of massive volcanic eruptions.
