Peat bogs, often seen as soggy expanses, hold a surprising superpower: storing vast amounts of carbon dioxide, a key greenhouse gas. These vital carbon sinks, covering only 3% of Earth's land, hold twice the carbon of all the world's forests combined.
A new study reveals a hidden threat to this crucial role – climate change's impact on tiny organisms living within the peat moss.
Peatlands store carbon because the cold, wet conditions slow down plant decomposition, keeping absorbed carbon locked away. However, rising temperatures are drying peatlands, turning them from carbon sinks into potential sources.
This new research, published in Global Change Biology, focuses on protists, microscopic creatures abundant in peat moss. Protists play a vital role in the carbon cycle – some consume CO2 for growth, while others feed on bacteria that help the moss thrive.
The study, led by Duke University's Jean Philippe Gibert and Christopher Kilner, investigated the effects of climate change on these protists in a northern Minnesota bog. Researchers built enclosures simulating future warming scenarios, with temperatures ranging from normal to 9 degrees Celsius warmer. Additionally, half the enclosures had normal air, while the others had CO2 levels expected by the end of the century if fossil fuel use continues unchecked.
After five years, the results surprised the researchers. "The protists reacted in unexpected ways," said Kilner. Under normal CO2 levels, most of the 200,000+ protists studied became more abundant with warming. However, this trend reversed under elevated CO2.
Furthermore, the combined effects of warming and high CO2 altered the protists' feeding habits and traits linked to their CO2 release during respiration, impacting their contribution to climate change.
The exact consequences for peatlands' future carbon storage are unclear, but they are likely significant. "These findings highlight a previously overlooked part of the peatland ecosystem that's sensitive to climate change," Gibert said, emphasizing the need to incorporate this new knowledge into future climate models.
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