The findings, published online in Nature Geoscience, represent a breakthrough in understanding the major "burp" of carbon, equivalent to burning the entire reservoir of fossil fuels on Earth, that occurred during the PETM.
"As geologists, it unnerves us that we don't know where this huge amount of carbon released in the PETM comes from," says Will Clyde, associate professor of Earth sciences at the University of New Hampshire and a co-author on the paper. "This is the first breakthrough we've had in a long time. It gives us a new understanding of the PETM." The work confirms that the PETM was not a unique event—the result, perhaps, of a meteorite strike—but a natural part of the Earth's carbon cycle.
Working in the Bighorn Basin region of Wyoming, a 100-mile-wide area with a semi-arid climate and stratified rocks that make it ideal for studying the PETM, Clyde and lead author Hemmo Abels of Utrecht University in the Netherlands found the first evidence of the smaller hyperthermal events on land. Previously, the only evidence of such events were from marine records.
"By finding these smaller hyperthermal events in continental records, it secures their status as global events, not just an ocean process. It means they are atmospheric events," Clyde says.
Their findings confirm that, like the smaller hyperthermals of the era that released carbon into the atmosphere, the release of carbon in the PETM had a similar origin. In addition, the warming-to-carbon release of the PETM and the other hyperthermals are similarly scaled, which the authors interpret as an indication of a similar mechanism of carbon release during all hyperthermals, including the PETM.
"It points toward the fact that we're dealing with the same source of carbon," Clyde says.
Working in two areas of the Bighorn Basin just east of Yellowstone National Park—Gilmore Hill and Upper Deer Creek—Clyde and Abels sampled rock and soil to measure carbon isotope records. They then compared these continental recordings of carbon release to equivalent marine records already in existence. Read the full report here.
Source: R&D Mag.
