TALLAHASSEE — Research from climate scientists around the world shows that higher carbon dioxide levels are a key cause of global warming. But carbon dioxide can be reduced through an environmental process in which rocks are chemically broken down (known as chemical weathering). Scientists have generally thought that this process takes hundreds of thousands to millions of years, helping to alleviate climate warming at an exceptionally slow rate.
However, new research led by a team from Florida State University and the National MagLab shows evidence that this process can occur at much shorter timescales — thousands to tens of thousands of years — suggesting that it could eventually counteract some of the warming caused by humans. The research was published Monday in Scientific Reports, an open access scientific journal of Nature Publishing Group.
"Increased chemical weathering is one of Earth's natural responses to carbon dioxide increases,” said Theodore Them, the lead researcher on the paper and a postdoctoral researcher at Florida State and the National MagLab. "The good news is that this process can help balance the effects of fossil fuel combustion, deforestation and agricultural practices. But the bad news is that it will not begin to counteract the excessive amounts of atmospheric carbon dioxide that humans are emitting for at least several thousand years."
As atmospheric carbon dioxide concentrations increase, the climate gets warmer. The warmer climate speeds up the chemical weathering processes, which consumes carbon dioxide from the atmosphere and mitigates the "greenhouse effect," cooling down the climate.
To conduct the study, the research team determined the rate at which rocks were chemically broken over an interval of rapid warming in the Early Jurassic Period. Much of the work was performed at Durham University in the United Kingdom. Using state-of-the-art analytical instrumentation within the National MagLab’s Geochemistry Group, the researchers processed and measured the trace elements of their rock samples.
"We noticed that, although chemical weathering increased significantly during this time interval, it was not as drastic as previously hypothesized," Them said. "What's really striking, however, is the planet’s ability to respond to these environmental changes on such short timescales."
The study also suggests that widespread oxygen-deficient oceans occurred because excess nutrients from the breakdown of rocks flowed into the oceans during the Early Jurassic Period. The researchers predict that future changes in weather patterns due to a warming planet will create more precipitation and increase the amount of river water and nutrients transported to coastal regions. A similar phenomenon is observed annually in the Gulf of Mexico and is called the Dead Zone, when nutrient-rich fresh water from the Mississippi River causes coastal algae blooms and de-oxygenation. This commingling is expected to increase both the size and duration of future coastal ocean de-oxygenation, negatively impacting sea life in those areas.
"Understanding ancient climatic change like this helps us anticipate the timing, implications and environmental response to better predict future climate scenarios," explained Jeremy Owens, a Florida State and National MagLab researcher involved in this work.
Other authors on the paper include Benjamin Gill (Virginia Tech), David Selby (Durham University), Darren Gröcke (Durham University) and Richard Friedman (University of British Columbia). The majority of this work was completed when Them was a PhD student at Virginia Tech.
By Kristin Roberts
The National High Magnetic Field Laboratory is the world’s largest and highest-powered magnet facility. Located at Florida State University, the University of Florida and Los Alamos National Laboratory, the interdisciplinary National MagLab hosts scientists from around the world to perform basic research in high magnetic fields, advancing our understanding of materials, energy and life. The lab is funded by the National Science Foundation (DMR-1157490) and the state of Florida. For more information, visit us online at nationalmaglab.org or follow us on Facebook, Twitter, Instagram and Pinterest at NationalMagLab.