News about the changing climate of the planet has gathered heat in the past couple of years and rightly so! Our planet is getting warmer and the mercury has been steadily rising since the start of Industrial Revolution. The average global temperature has increased by about 0.8 degree Celsius since the 1880’s. More so, temperatures in the Artic have been rising at an alarming rate of 0.6C per decade over the last 30 years and is thawing the permafrost layers.

Permafrost is defined as soil that has been below 0 degree Celsius for at least two years. It comprises of sediments of plants and animals frozen over thousands of years ago and is reported to have almost 1,700 billion tons of trapped organic carbon.

Warmer temperatures and rapid thawing of the permafrost sediments makes the organic matter readily available for microbial decomposition. New findings suggest that microorganisms residing in the permafrost layer could contribute substantially to global warming.

Certain microorganisms in the permafrost environment have the ability to decompose organic carbon. Microbial breakdown of carbon occurs through diverse interdependent biogeochemical processes. In this unique niche, microorganisms work together as a community and are a part of an efficient food web. Members at the top of this food chain breakdown complex cellulose into simpler sugars that are passed down to fermenters. Consumers of the fermented brews, the methanogens, produce methane as the end product of their metabolism. Furthermore, there are also those who utilize methane and in turn release carbon dioxide into the atmosphere. It is well established that increase in emission levels of both these greenhouse gases contributes significantly towards warming of the earth’s atmosphere.

Typically, microbial activity in the permafrost is limited due to subzero temperatures and low nutrient availability, shielding the carbon from microbial decomposition and maintaining equilibrium in this delicate ecosystem. Rising temperatures and defrosting of the otherwise insulated sediments can accelerate the microbial decomposition and release of greenhouse gases carbon dioxide and methane creating a feedback that could impact the rate of climate change.

Next generation ‘omics’ technologies are playing a vital role in examining the magnitude of this impact. These techniques have enabled researchers to uncover carbon cycling mechanisms of the microbial communities that thrive within permafrost. Study of their genes and proteins is facilitating researchers identify the key players involved in the assimilation of organic matter.

Understanding their metabolism coupled with the biogeochemical data can provide insight into how the microbial residents in the permafrost are adapting to the altering conditions. Efforts to keep a track of these evolving populations will advance our understanding of the permafrost ecosystem and help scientists make informed predictions about the changing climate of our planet.

References:

  1. NASA Earth Observatory (https://earthobservatory.nasa.gov/WorldOfChange/decadaltemp.php)
  2. Genome-centric view of carbon processing in thawing permafrost. Ben J. Woodcroft, Caitlin M. Singleton, Joel A. Boyd, Paul N. Evans, Joanne B. Emerson, Ahmed A. F. Zayed, Robert D. Hoelzle, Timothy O. Lamberton, Carmody K. Mccalley, Suzanne B. Hodgkins, Rachel M. Wilson,Samuel O. Purvine, Carrie D. Nicora, Changsheng Li, Steve Frolking, Jeffrey P. Chanton, Patrick M. Crill, Scott R. Saleska ,Virginia I. Rich & Gene W. Tyson. Nature 2018. Published 16 July 2018.
  3. Permafrost Meta-Omics and Climate Change. Rachel Mackelprang, Scott R. Saleska, Carsten Suhr Jacobsen, Janet K. Jansson, and Neslihan Taş. Annual Review of Earth and Planetary Sciences. Annual Review of Earth and Planetary Sciences Volume 44, 2016
  4. Climate change and the permafrost carbon feedback. E. A. G. Schuur, A. D. McGuire, C. Schädel, G. Grosse, J. W. Harden, D. J. Hayes, G. Hugelius, C. D. Koven, P. Kuhry, D. M. Lawrence, S. M. Natali, D. Olefeldt, V. E. Romanovsky, K. Schaefer, M. R. Turetsky, C. C. Treat & J. E. Vonk. Nature. 09 April 2015.

Author

Snehal Joshi 

 

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Photo by Anders Jildén on Unsplash