Microbes aren't accelerating global warming as expected

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London, April 17 (ANI): Soil microbes are producing less atmospheric carbon dioxide than scientists expected, a new American research has found.

The findings of the study, conducted by researchers at the University of California at Irvine, Colorado State University and Yale University, have appeared in a paper published on-line this week in the journal Nature Geoscience.

Saran Twombly, program director in NSF's Division of Environmental Biology, said: "Microbes continually surprise us in the diverse ways they respond to environmental conditions.

"Microbes play a central role in ecological processes," said Twombly, "and their responses change our understanding of natural communities in fundamental ways."

Conventional scientific wisdom holds that even a few degrees of human-caused climate warming will shift fungi and bacteria that consume soil-based carbon into overdrive, and that their growth will accelerate the release of carbon dioxide into the atmosphere.

But a research team led by ecologist Steve Allison of UC Irvine took a closer look, and found something different.

While microbial soil decomposition, and resulting carbon dioxide emissions, increase initially, microbes eventually overheat and grow more slowly.

As their numbers decline, they release decreasing amounts of climate-warming greenhouse gases.

Allison said: "Microbes are the engines that drive carbon cycling in soils.

"In a balanced environment, plants store carbon in the soil and microbes use that carbon to grow. Enzymes produced by microbes convert soil carbon into atmospheric carbon dioxide."

A previous study by Mark Bradford of Yale and Matthew Wallenstein of Colorado State found that microbes became less efficient at decomposing soil carbon after several years of experimental warming.

They asked Allison to develop a computer model to test how adaptation of microbes to climate change might affect the carbon cycle.

Bradford said: "The issue we have in predicting whether soil carbon loss will accelerate climate warming is that the microbial processes causing this loss are poorly understood.

"More research in this area will help reduce uncertainties in climate prediction."

In the resulting computer model, microbes became less efficient at converting their carbon food source into biomass as climate warmed.

In short, the microbes were not well adapted to a warmer climate. s their growth slowed, so did enzyme production.

Allison said: "When we developed a model based on the actual biology of soil microbes, we found that soil carbon may not be lost to the atmosphere as the climate warms.

"Conventional ecosystem models that didn't include enzymes did not make the same predictions."

The next steps include studying more microbes and more ecosystems.

Microbes from a Massachusetts forest inspired this study, then Allison began collecting soil samples from California, Alaska, Maine and Costa Rica.

"Nearly one-third of all soil-based carbon is sequestered in permafrost or Arctic regions, which might respond differently to warming," said Wallenstein, who is researching sites in Greenland and Alaska.

Allison said: "We need to develop more models to include microbe diversity.

"But the general principle that's important in our model is the decline of carbon dioxide production after an initial increase." (ANI)

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