Volcanoes acted as a safety valve for Earth's long-term climate
The researchers, working with colleagues at the University of Sydney, Australian National University (ANU), University of Ottawa and University of Leeds, explored the combined impact of processes in the solid Earth, oceans and atmosphere over the past 400 million years. Their findings are published in the journal Nature Geoscience.
Natural break-down and dissolution of rocks at Earth's surface is called chemical weathering. It is critically 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 mechanism 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, 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".
"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".
Continental volcanic arcs such as this one in Kamchatka, Russia, are rapidly weathered, driving CO2 removal from the atmosphere over geological time. Credit: Tom Gernon, University of Southampton
Global chemical weathering has been dominated by volcanic arcs over the past 400 million years (pictured: a river draining Bakening volcano, Kamchatka Peninsula, Russia). Credit: Tom Gernon, University of Southampton