Scientists at the University of Southhampton have discovered that large chains of volcanoes have been responsible for both emitting and then removing atmospheric carbon dioxide over geological time thus stabilizing temperatures at Earth’s surface.
The team explored the combined impact of processes in the solid Earth, oceans and atmosphere over the past 400 million years.
Natural break-down and dissolution of rocks at Earth’s surface is termed chemical weathering. It is extremely important because the products of weathering (elements like calcium and magnesium) are flushed via rivers to the oceans, where they form minerals that lock up CO2. This feedback loop regulates atmospheric CO2 levels and in turn global climate over geological time.
“In this respect, weathering of the Earth’s surface serves as a geological thermostat”, says lead author Dr. Tom Gernon. “But the underlying controls have proven difficult to determine due to the complexity of the Earth system”.
To unravel the complexity, the team constructed a “Earth network”, incorporating machine learning algorithms and plate tectonic reconstructions. This enabled them to identify the dominant interactions within the Earth system, and how they evolved over time.
The team discovered that continental volcanic arcs were the most important driver of weathering intensity over the past 400 million years. These volcanoes are some of the highest and fastest eroding features on Earth. Because volcanic rocks are fragmented and chemically reactive, they are rapidly weathered and flushed into the oceans.
Co-author Martin Palmer said, “It’s a balancing act. On the one hand, these volcanoes pumped out large amounts of CO2 that increased atmospheric CO2 levels. On the other hand, these same volcanoes helped removed that carbon via rapid weathering reactions.”
https://phys.org/news/2021-08-volcanoes-safety-valve-earth-long-term.html