Over geological time, scientists at the University of Southampton revealed that huge chains of volcanoes were responsible for both producing and absorbing atmospheric carbon dioxide (CO2). Temperatures at the Earth’s surface were stabilized as a result of this.
The researchers studied the combined impact of processes in the solid Earth, oceans, and atmosphere over the past 400 million years alongside colleagues from the University of Sydney, Australian National University (ANU), University of Ottawa, and the University of Leeds. Their findings have been published in Nature Geoscience.
A safety valve is a device on a boiler or similar device that automatically opens when a particular pressure is reached, preventing the boiler from exploding. Such phenomena, as well as volcanoes erupting and venting the magma’s pressure, are prevented via safety valves.
Chemical weathering is the natural breakdown and dissolving of rocks at the Earth’s surface. Because the results of weathering (elements like calcium and magnesium) are discharged into rivers and then into the oceans, where they create minerals that lock up CO2, it’s vital. Over geological time, this feedback process regulates atmospheric CO2 levels and, as a result, world temperature.
“In this respect, weathering of the Earth’s surface serves as a geological thermostat,” says lead author Dr. Tom Gernon, Associate Professor in Earth Science at the University of Southampton, and a Fellow of the Turing Institute. “But the underlying controls have proven difficult to determine due to the complexity of the Earth system.”
A safety valve’s main purpose is to keep property and people safe. Because a safety valve is frequently the last line of defense against catastrophic failure under pressure, it is critical that it functions at all times, i.e., it be 100 percent reliable.
“Many Earth processes are interlinked, and there are some major time lags between processes and their effects,” explains Eelco Rohling, Professor in Ocean and Climate Change at ANU and co-author of the study. “Understanding the relative influence of specific processes within the Earth system response has therefore been an intractable problem.”
The safety valves would be chosen based on the boiler’s seam evaporation capability. The safety valve is chosen so that all of the safety valves open or pop up at a lower pressure than the drum’s design pressure, say 8 to 10% less.
The researchers devised a revolutionary “Earth network” that included machine-learning techniques and plate tectonic reconstructions in order to decipher the complexities. They were able to identify the primary interactions within the Earth system, as well as how they evolved over time, as a result of this.
In this respect, weathering of the Earth’s surface serves as a geological thermostat. But the underlying controls have proven difficult to determine due to the complexity of the Earth system.
Dr. Tom Gernon
Continental volcanic arcs were discovered to be the most important driver of weathering intensity over the last 400 million years, according to researchers. Continental arcs today include chains of volcanoes such as the Andes in South America and the Cascades in the United States.
These volcanoes are among the planet’s tallest and fastest-eroding landforms. Volcanic rocks are quickly eroded and washed into the waters because they are fractured and chemically reactive.
Martin Palmer, Professor of Geochemistry at the University of Southampton and co-author of the study, said: “It’s a balancing act. On one hand, these volcanoes pumped out large amounts of CO2 that increased atmospheric CO2 levels. On the other hand, these same volcanoes helped remove that carbon via rapid weathering reactions.”
The findings call into question a long-held belief that the Earth’s climate stability over tens to hundreds of millions of years is due to a balance between seafloor weathering and continental interior weathering.
“The idea of such a geological tug of war between the landmasses and the seafloor as a dominant driver of Earth surface weathering is not supported by the data,” Dr. Gernon states.
“Unfortunately, the results do not mean that nature will save us from climate change,” stresses Dr. Gernon. “Today, atmospheric CO2 levels are higher than at any time in the past 3 million years, and human-driven emissions are about 150 times larger than volcanic CO2 emissions. The continental arcs that appear to have saved the planet in the deep past are simply not present at the scale needed to help counteract present-day CO2 emissions.”
However, the findings of the researchers are still important for understanding how society might deal with the current climate issue. Artificially increased rock weathering, which involves pulverizing and spreading boulders across the land to accelerate chemical reaction rates, could play a crucial role in safely removing CO2 from the atmosphere.
The findings suggest that calc-alkaline volcanic materials (those containing calcium, potassium, and sodium), such as those found in continental arc environments, maybe the best choice for such systems.
This is by no means a silver bullet solution to the climate crisis we urgently need to reduce CO2 emissions in line with IPCC mitigation pathways, full stop. Our assessment of weathering feedbacks over long timescales may help in designing and evaluating large-scale enhanced weathering schemes, which is just one of the steps needed to counteract global climate change,” Dr Gernon concludes.
