Soil carbon feedback

Map showing extent and types of permafrost in the Northern Hemisphere

The soil carbon feedback concerns releases of carbon from soils, in response to global warming, known as a positive climate feedback. Soil carbon contains three times as much carbon as Earth's atmosphere,[1] which makes them crucial to understand related carbon fluxes. However, other studies suggest that soils contain twice as much carbon than contained in the atmosphere.[2] Measurements imply that 4°C of warming increases annual soil respiration by up to 37%.[3] Climate models do not account for effects of biochemical heat release associated with microbial decomposition.[4]

General

An observation based study on future climate change, on the soil carbon feedback, conducted since 1991 in Harvard, suggests release of about 190 petagrams of soil carbon, the equivalent of the past two decades of greenhouse gas emissions from fossil fuel burning, until 2100 from the top 1-meter of Earth's soils, due to changes in microbial communities under elevated temperatures.[5][6]

Thawing of permafrost (frozen ground), which is located in higher latitudes, the Arctic and sub-Arctic regions, suggest based on observational evidence a linear and chronic release of greenhouse gas emissions with ongoing climate change from these carbon dynamics.[7]

A study published in 2011 identified a so-called compost-bomb instability, related to a tipping point with explosive soil carbon releases from peatlands. The authors noted that there is a unique stable soil carbon equilibrium for any fixed atmospheric temperature.[4]

A 2018 study concludes, "Climate-driven losses of soil carbon are currently occurring across many ecosystems, with a detectable and sustained trend emerging at the global scale."[2][8]

See also

References

  1. ↑ "Study: Soils Could Release Much More Carbon Than Expected as Climate Warms". Berkeley Lab. March 9, 2017.
  2. 1 2 Bond-Lamberty et al. (2018). "Globally rising soil heterotrophic respiration over recent decades". Nature. doi:10.1038/s41586-018-0358-x.
  3. ↑ Caitlin E. Hicks Pries, C. Castanha, R. C. Porras, M. S. Torn (2017). "The whole-soil carbon flux in response to warming". AAAS. doi:10.1126/science.aal1319.
  4. 1 2 S. Wieczorek, P. Ashwin, C. M. Luke, P. M. Cox (2011). "Excitability in ramped systems: the compost-bomb instability". The Royal Society. doi:10.1098/rspa.2010.0485.
  5. ↑ "One of the oldest climate change experiments has led to a troubling conclusion". The Washington Post. October 5, 2017.
  6. ↑ Melillo et al. (2017). "Long-term pattern and magnitude of soil carbon feedback to the climate system in a warming world". AAAS. doi:10.1126/science.aan2874.
  7. ↑ Schuur et al. (2014). "Climate change and the permafrost carbon feedback". Nature. doi:10.1038/nature14338.
  8. ↑ "In vicious cycle, warmer dirt makes climate change worse, study says". AP. 2018.
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