Researchers at the University of Southampton recently discovered that volcanoes play an important role in stabilizing temperatures at Earth’s surface. According to the scientists, volcanoes have been responsible over geological time for cycles of emitting and subsequently removing atmospheric carbon dioxide (CO2).
Volcanoes achieve such thermic regulation through a process called chemical weathering. During this natural breakdown and dissolution of rocks, elements such as calcium or magnesium are flushed by rivers to the oceans, where they form minerals capable of regulating atmospheric CO2 levels and, thus, the global climate at large.
“In this respect, weathering of the Earth’s surface serves as a geological thermostat,” said study lead author Professor Tom Gernon. “But the underlying controls have proven difficult to determine due to the complexity of the Earth system.”
By incorporating machine-learning algorithms and plate tectonic reconstructions into computer models, Dr. Gernon and his team found that continental volcanic arcs have been the most important driver of chemical weathering during the past 400 million years.
“It’s a balancing act,” explained study co-author professor Martin Palmer. “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.”
Since atmospheric CO2 levels are currently higher than they have been in three million years, volcanic activity that seemed to have saved the planet before is currently unable to achieve similar results.
“Unfortunately, the results do not mean that nature will save us from climate change,” said Dr. Gernon. “Today, atmospheric CO2 levels are higher than at any time in the past three 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 team’s findings offer insights into possible ways of dealing with the climate crisis. Artificially enhancing chemical weathering through pulverizing and spreading rocks across land in order to increase the speed of chemical reaction rates could be a key factor in eliminating atmospheric CO2.
“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,” concluded Dr. Gernon. “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.”
The research was published in the journal Nature Geoscience.