The Permafrost Is Outgassing

As the ice melts everywhere, the permafrost (permanently frozen soil) is also melting.  When this frozen muck thaws, it releases swamp gas—lots of CO2 and methane, for example—into the atmosphere.

Depending on the amount of freezing, thawing, and accumulation of seasonal debris (dead plants), the permafrost alternatively sucks in and puts out Carbon.

Since the last ice age, permafrost has generally remained frozen except for relatively shallow surface areas.  This has encapsulated the organic materials frozen there.  During the short summer, plants grow and absorb Carbon from the atmosphere, and the winter cold refrigerates the dead foliage, preventing decay back into the atmosphere.  So, up to now, permafrost has been a Carbon sink, soaking up Carbon out of the atmosphere .

As global air temperatures have risen, and polar surface areas even more rapidly warm, permafrost has begun to perma-melt.  Ultimately, this will tip the balance, so that the soil no longer retains additional Carbon.  Worse, the Carbon frozen underground over centuries will be released into the atmosphere [1].  This, like reduced albedo, is a potential positive feedback, speeding up warming.

However, data from these cold, remote regions is sparse, so it hasn’t been clear how much Carbon these regions absorb (in the summer) and emit (in the winter).  There are vast areas of permafrost in the Northern hemisphere, with a variety of vegetation, microbes, and seasonal patterns.

This winter, an international team reports on a comprehensive collection of measured CO2 emissions from northern permafrost.  They combine these measures with satellite observations of vegetation and conditions, and built a model of the physics.  This study indicates that CO2 emissions may already exceed uptake [2].

Source: NASA Earth Science News [3]

Extrapolating the model with different scenarios for global temperatures, the CO2 emissions could increase 17-41% by year 2100.  This would place it somewhere in the 1-2 billion tons or Carbon per year (compared to 30+ billion tons per year released due to human activities).  It looks like human generated warming has an additional side effect, causing tons of Carbon to be released from permafrost, which will only increase warming further.

Of course, these estimates are extrapolations from relatively sparse data points, and are aggregated over huge spaces and time periods.  (E.g., they estimate emissions for 25×25 km areas for a month.)  The study also neglects the “shoulder seasons” (spring and fall), and other gasses including methane.  Nevertheless, these results seem to be in line with data and theory, so they are plausible, as are the projections into the future.

The upshot is that the arctic is flipping from a Carbon sink to a Carbon source—pretty much the opposite of what we should want to see.

“The warmer it gets, the more carbon will be released into the atmosphere from the permafrost region, which will add to further warming,” said co-author and WHRC scientist Brendan Rogers. “It’s concerning that our study, which used many more observations than ever before, indicates a much stronger Arctic carbon source in the winter. We may be witnessing a transition from an annual Arctic carbon sink to a carbon source, which is not good news.” (From [3])

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1. John L. Campbell, Arctic loses carbon as winters wane. Nature Climate Change, 9 (11):806-807, 2019/11/01 2019. https://doi.org/10.1038/s41558-019-0604-8
2. Susan M. Natali, Jennifer D. Watts, Brendan M. Rogers, Stefano Potter, Sarah M. Ludwig, Anne-Katrin Selbmann, Patrick F. Sullivan, Benjamin W. Abbott, Kyle A. Arndt, Leah Birch, Mats P. Björkman, A. Anthony Bloom, Gerardo Celis, Torben R. Christensen, Casper T. Christiansen, Roisin Commane, Elisabeth J. Cooper, Patrick Crill, Claudia Czimczik, Sergey Davydov, Jinyang Du, Jocelyn E. Egan, Bo Elberling, Eugenie S. Euskirchen, Thomas Friborg, Hélène Genet, Mathias Göckede, Jordan P. Goodrich, Paul Grogan, Manuel Helbig, Elchin E. Jafarov, Julie D. Jastrow, Aram A. M. Kalhori, Yongwon Kim, John S. Kimball, Lars Kutzbach, Mark J. Lara, Klaus S. Larsen, Bang-Yong Lee, Zhihua Liu, Michael M. Loranty, Magnus Lund, Massimo Lupascu, Nima Madani, Avni Malhotra, Roser Matamala, Jack McFarland, A. David McGuire, Anders Michelsen, Christina Minions, Walter C. Oechel, David Olefeldt, Frans-Jan W. Parmentier, Norbert Pirk, Ben Poulter, William Quinton, Fereidoun Rezanezhad, David Risk, Torsten Sachs, Kevin Schaefer, Niels M. Schmidt, Edward A. G. Schuur, Philipp R. Semenchuk, Gaius Shaver, Oliver Sonnentag, Gregory Starr, Claire C. Treat, Mark P. Waldrop, Yihui Wang, Jeffrey Welker, Christian Wille, Xiaofeng Xu, Zhen Zhang, Qianlai Zhuang, and Donatella Zona, Large loss of CO2 in winter observed across the northern permafrost region. Nature Climate Change, 9 (11):852-857, 2019/11/01 2019. https://doi.org/10.1038/s41558-019-0592-8
3. Samson Reiny and Miles Grant, Permafrost Becoming a Carbon Source Instead of a Sink, in NASA Earth Science News. 2019. https://earthobservatory.nasa.gov/images/145880/permafrost-becoming-a-carbon-source-instead-of-a-sink

The Polar Plantscape Is Changing Rapidly

As the Anthropocene climate changes accelerate, we are seeing life forms (with the exception of humans) responding to the changing conditions.  Animals are moving uphill and northward, following the warming trends.

At the same time, plants are “migrating” and adapting.  Oak trees and other species are “moving” north, inhabiting areas that were previously too cold, and dying out in over heated southern ranges.

Even in polar regions, the inhabitants are adapting to the melting ice and warming air.  Penguins seem to be shifting nesting grounds, presumably following changing conditions.

This fall two studies report on how the plant (or at least non-animal) life is “moving” in the Arctic and Antarctic.

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Until recently, some areas of Antarctica had large areas of moss that was covered by snow and ice in the winter.  In the summer, the cover melted these beds were exposed to the sun.  In this very wet, very sunny situation, the moss greened and thrived.  In fact, the beds seem to have persisted in the same location for years, probably centuries.

These are the “miniature old growth forests” of East Antarctica.  They are also home to many (small) animals and other species such as fungus.

A new report shows that some of these beds are rapidly dying out, apparently because the climate is drying out [4].  (Growing moss is all about water.)  Other more tolerant mosses are invading the area.

Tiny as they are, this rapid change to the “moss forest” is a huge ecological shift.

At the same time, another study reports that in northern regions tundra plants such as grasses have grown taller, and larger species are moving north [2].  In fact, getting on twice as tall.  There are no trees in these harsh locations, so these ankle high species are the “miniature old growth forests” of the tundra.  And they are bulking up in response to warmer, wetter conditions.

“compare it to the ecosystems around your house like the forest nearby – if you imagined that forest getting twice as tall; that is a pretty dramatic change,” (Isla Myers-Smith, quoted in [1])

The presence of these taller plants might create a positive feedback, insulating the soil (e.g., by trapping blowing snow) and lowering the albedo (due to foliage sticking above the snow).  These effects could contribute to more melting of ice and permafrost, further warming the area.

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Not only are the old growth forests shrinking and dying, these “miniature” old growths, mosses and grasses and such, are also changing rapidly.

It’s kind of a cool image, “miniature old growth forests”.

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(For the record, the data is available from “Team Tundra” and the Austrailian Antarctic Data Center (AADC) )

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1. Jonathan Amos, Taller plants moving into warmer Arctic, in BBC News – Science & Environment. 2018. https://www.bbc.com/news/science-environment-45652152
2. Anne D. Bjorkman, Isla H. Myers-Smith, Sarah C. Elmendorf, Signe Normand, Nadja Rüger, Pieter S. A. Beck, Anne Blach-Overgaard, Daan Blok, J. Hans C. Cornelissen, Bruce C. Forbes, Damien Georges, Scott J. Goetz, Kevin C. Guay, Gregory H. R. Henry, Janneke HilleRisLambers, Robert D. Hollister, Dirk N. Karger, Jens Kattge, Peter Manning, Janet S. Prevéy, Christian Rixen, Gabriela Schaepman-Strub, Haydn J. D. Thomas, Mark Vellend, Martin Wilmking, Sonja Wipf, Michele Carbognani, Luise Hermanutz, Esther Lévesque, Ulf Molau, Alessandro Petraglia, Nadejda A. Soudzilovskaia, Marko J. Spasojevic, Marcello Tomaselli, Tage Vowles, Juha M. Alatalo, Heather D. Alexander, Alba Anadon-Rosell, Sandra Angers-Blondin, Mariska te Beest, Logan Berner, Robert G. Björk, Agata Buchwal, Allan Buras, Katherine Christie, Elisabeth J. Cooper, Stefan Dullinger, Bo Elberling, Anu Eskelinen, Esther R. Frei, Oriol Grau, Paul Grogan, Martin Hallinger, Karen A. Harper, Monique M. P. D. Heijmans, James Hudson, Karl Hülber, Maitane Iturrate-Garcia, Colleen M. Iversen, Francesca Jaroszynska, Jill F. Johnstone, Rasmus Halfdan Jørgensen, Elina Kaarlejärvi, Rebecca Klady, Sara Kuleza, Aino Kulonen, Laurent J. Lamarque, Trevor Lantz, Chelsea J. Little, James D. M. Speed, Anders Michelsen, Ann Milbau, Jacob Nabe-Nielsen, Sigrid Schøler Nielsen, Josep M. Ninot, Steven F. Oberbauer, Johan Olofsson, Vladimir G. Onipchenko, Sabine B. Rumpf, Philipp Semenchuk, Rohan Shetti, Laura Siegwart Collier, Lorna E. Street, Katharine N. Suding, Ken D. Tape, Andrew Trant, Urs A. Treier, Jean-Pierre Tremblay, Maxime Tremblay, Susanna Venn, Stef Weijers, Tara Zamin, Noémie Boulanger-Lapointe, William A. Gould, David S. Hik, Annika Hofgaard, Ingibjörg S. Jónsdóttir, Janet Jorgenson, Julia Klein, Borgthor Magnusson, Craig Tweedie, Philip A. Wookey, Michael Bahn, Benjamin Blonder, Peter M. van Bodegom, Benjamin Bond-Lamberty, Giandiego Campetella, Bruno E. L. Cerabolini, F. Stuart Chapin, William K. Cornwell, Joseph Craine, Matteo Dainese, Franciska T. de Vries, Sandra Díaz, Brian J. Enquist, Walton Green, Ruben Milla, Ülo Niinemets, Yusuke Onoda, Jenny C. Ordoñez, Wim A. Ozinga, Josep Penuelas, Hendrik Poorter, Peter Poschlod, Peter B. Reich, Brody Sandel, Brandon Schamp, Serge Sheremetev and Evan Weiher, Plant functional trait change across a warming tundra biome. Nature, 562 (7725):57-62, 2018/10/01 2018. https://doi.org/10.1038/s41586-018-0563-7
3. Victoria Gill, Climate change kills Antarctica’s ancient moss beds, in BBC News – Science & Environment. 2018. https://www.bbc.com/news/science-environment-45629395
4. Sharon A. Robinson, Diana H. King, Jessica Bramley-Alves, Melinda J. Waterman, Michael B. Ashcroft, Jane Wasley, Johanna D. Turnbull, Rebecca E. Miller, Ellen Ryan-Colton, Taylor Benny, Kathryn Mullany, Laurence J. Clarke, Linda A. Barry, and Quan Hua, Rapid change in East Antarctic terrestrial vegetation in response to regional drying. Nature Climate Change, 8 (10):879-884, 2018/10/01 2018. https://doi.org/10.1038/s41558-018-0280-0