An invisible world exists beneath our feet, full of thriving organisms that few human eyes will ever see. Now, researchers have found that as global temperatures steadily rise, previously dormant bacteria are coming alive, which could further complicate worsening climate conditions on Earth.
A longstanding challenge in the study of climate change involves how it impacts the microbiome within Earth’s soil, which plays a significant role in helping researchers calculate global climate models. This is partly due to the role microorganisms play in the regulation of carbon fluxes that have a significant impact on climate.
With warming temperatures, some scientists warn that an increase in microbial activity in Earth’s soil could impact carbon stocks, which are especially prevalent in soils at higher latitudes where the activity of these organisms had once been limited by cooler temperatures.
Now, as more microorganisms awaken with rising temperatures, the carbon stocks within these soils are becoming more susceptible to decomposition and could lead to increases in the release of carbon into the atmosphere.
The findings were the result of a new study by researchers at the University of Vienna’s Centre for Microbiology and Environmental Systems Science (CeMESS).
According to the team behind the study, their findings represent a potentially major shift in how scientists view microbial activity in our soil, and the role these organisms play in the global carbon cycle, as well as its relationship to Earth’s climate.
Previously, it had been assumed that the release of carbon into the atmosphere was due to the accelerated growth of existing microbes due to warmer temperatures, although the new findings confirm the primary mechanism to be the activation of dormant bacteria.
Andreas Richter, lead author of the study and professor at the University’s Centre for Microbiology and Environmental Systems Science, says soils are the planet’s most significant supply of organic carbon, and the microorganisms within them govern the Earth’s carbon cycle as they break down materials, releasing carbon dioxide in the process.
Of particular concern to researchers is what is called soil carbon-climate feedback, which is the cycle that arises from the proportional emission of carbon dioxide by microorganisms that awaken as temperatures rise, thereby contributing to overall global warming trends.
As part of their research, Richter and his colleagues traveled to a region of Iceland where elevated soil temperatures compared with nearby areas were especially significant.
Dennis Metze Ph.D., the study’s lead author, said that increased microbial growth was evident in areas that had seen more than half a century of consistent soil warming.
“But remarkably, the growth rates of microbes in warmer soils were indistinguishable to those at normal temperatures,” Metze added, noting that the key difference the researchers found was bacterial diversity, in that warmer soils had a much greater variety of different active microbes.
The team made these discoveries through the collection of soil cores, and the application of state-of-the-art isotope probing capabilities.
Christina Kaiser, an associate professor involved with the study, likened the complexity of soil’s microbiomes and their response to climate “a ‘black box’ in climate modeling.”
The team says their findings will likely assist in the generation of more accurate models going forward and could help to unravel some of the existing mysteries involving how microbial communities respond to warmer temperatures, and their relationship to the overall carbon cycle going forward.
The team’s new study, “Soil warming increases the number of growing bacterial taxa but not their growth rates,” was published in the journal Science Advances on February 23, 2024.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.