Privileged Planet: carbon cycle bacterial contribution (Introduction)

by David Turell , Friday, April 23, 2021, 16:21 (1311 days ago) @ David Turell

Based on very new analysis in hot spring:

https://www.sciencemag.org/news/2021/04/microbes-are-siphoning-massive-amounts-carbon-e...

"A few kilometers below our feet lies a hidden world of microbes whose chemical reactions are shaping the long-term habitability of the planet. A new study suggests some of these microbes are siphoning off massive amounts of carbon as it enters Earth, using it to fuel their own sunless ecosystems. The carbon, prevented from being buried even deeper in Earth, will eventually escape back into the atmosphere—where it could help warm the planet. Researchers say the microbes represent an overlooked factor in efforts to balance Earth’s deep carbon cycle.

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"Warming from human emissions of carbon dioxide (CO2) will be the deciding factor for surface temperatures in the coming centuries. But there is also a deeper carbon cycle, one that plays out over hundreds of millions of years. Slabs of ocean crust dive into Earth’s mantle at subduction zones, taking carbon down with them for long-term storage in the mantle. Some of this carbon, dissolved in rising blobs of magma and gasses, gets re-emitted at volcanoes. But much of what goes down doesn’t come back up, and researchers still don’t fully understand why.

"Scientists found some of that missing carbon in 2017, when they examined gasses and fluids bubbling up from more than 20 hot springs in Costa Rica. The springs were 40 to 120 kilometers above the subduction zone where the Cocos Plate dives beneath Central America. Scientists found that a portion of the CO2 that goes down with the descending plate is turned into rock and never reaches the deep mantle or the atmosphere. But they also saw hints that more CO2 was being siphoned off the plate than rock formation alone could explain.

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"These microbes could be sequestering 2% to 22% of the carbon previously thought to reach the deep mantle, the researchers report today in Nature Geoscience. By keeping carbon close to the surface, where it is likely to eventually percolate up and re-enter the atmosphere, the microbes may be helping warm the planet over the long term, although this would require additional research to confirm.

"Two percent may not have much of an effect on the deep carbon cycle, says Oliver Plümper, an expert in rock-fluid interactions at Utrecht University who was not involved in the study. But 22% would be “quite exciting.” He says this calculation constitutes an important piece to the puzzle of the deep carbon cycle, and it could impact projections of how stable Earth’s climate will remain in the long term—and how long the planet is likely to be habitable.

"The researchers also found evidence for a second group of microbes that live off the organic leftovers of the carbon-sequestering bacteria. “There’s a whole world happening underneath Costa Rica,” says Karen Lloyd, co-author and microbiologist at the University of Tennessee, Knoxville. The researchers suspect similar activity is taking place in other subduction zones all over the world."

Comment: ninety-nine percent of evolved organisms might be gone, but bacteria are still here because they are important for Earth's continuing warm life-friendly climate. So logical it means a designing mind must be running things. The 99% were not needed and necessarily discarded. Life started with Archaea bacteria and remain to help out in whatever process needs them. dhw can't see the clever planning mind running the show.