This story by Caitlin Hayes is shared jointly with the Cornell Chronicle newsroom.

Study co-author Joel E. Kostka is the Tom and Marie Patton Distinguished Professor and associate chair for Research in the School of Biological Sciences with a joint appointment in the School of Earth and Atmospheric Sciences. He also serves as faculty director of Georgia Tech for Georgia's Tomorrow. 

The Kostka Lab works in peatland ecosystems to quantify changes in microbial communities brought on by climate change drivers. In particular, next generation gene sequencing and omics approaches are employed to investigate the microbial groups that mediate organic matter degradation and the release of greenhouse gases.

Peatlands make up just 3% of the earth’s land surface but store more than 30% of the world’s soil carbon, preserving organic matter and sequestering its carbon for tens of thousands of years. A new study sounds the alarm that an extreme drought event could quadruple peatland carbon loss in a warming climate. 

In the study, published October 23 in Science, researchers find that, under conditions that mimic a future climate (with warmer temperatures and elevated carbon dioxide), extreme drought dramatically increases the release of carbon in peatlands by nearly three times. This means that droughts in future climate conditions could turn a valuable carbon sink into a carbon source, erasing between 90 and 250 years of carbon stores in a matter of months.

“As temperatures increase, drought events become more frequent and severe,  making peatlands more vulnerable than before,” said Yiqi Luo, senior author and the Liberty Hyde Bailey Professor in the School of Integrative Plant Science’s Soil and Crop Sciences Section, in the College of Agriculture and Life Sciences (CALS) at Cornell University. “We add new evidence to show that with peatlands, the stakes are high. We observed that these extreme drought events can wipe out hundreds of years of accumulated carbon, so this has a huge implication.”

“To me, this study is striking in that it shows that around 10 to 100 years of carbon uptake by one of the most important global soil carbon stores can be erased by just two months of extreme drought,” adds Joel Kostka, Tom and Marie Patton Distinguished Professor in Biological Sciences at Georgia Tech.

It was already well-established that drought reduces ecosystem productivity and increases carbon release in peatlands, but this study is the first to examine how that carbon loss is exacerbated as the planet warms and more carbon dioxide enters the atmosphere. The Intergovernmental Panel on Climate Change estimates extreme drought will become 1.7 to 7.2 times more likely in the near future. 

Read the full story in the Cornell newsroom. 

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Other co-authors include Cornell postdoctoral researchers Jian Zhou and Ning Wei; senior research associate Lifen Jiang; and researchers from Georgia Institute of Technology, Florida State University, the U.S. Department of Agriculture (USDA), ETH Zurich, Northern Arizona University, the Australian National University, the University of Western Ontario and Duke University.

Funding for the study came in part from the National Science Foundation, USDA, the New York State Department of Environmental Conservation and the New York State Department of Agriculture and Markets.