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Increased methane loss due to later soil freezing in the Arctic may explain renewed atmospheric methane growth
Kyle
Arndt, San Diego State University, kyleaarndt@gmail.com
(Presenter)
Walter
Oechel, San Diego State University, woechel@mail.sdsu.edu
Jordan
Goodrich, Scripps Institute of Oceanography, jordan.p.goodrich@gmail.com
Aram
Kalhori, San Diego State University, akalhori@mail.sdsu.edu
Josh
Hashemi, San Diego State University, joshhashemi@gmail.com
Colm
Sweeney, NOAA/ESRL GMD, colm.sweeney@noaa.gov
Donatella
Zona, San Diego State University (USA), dzona@mail.sdsu.edu
Over the last decade, the methane (CH4) atmospheric concentration is increasing at the fastest rate since the last twenty years, and isotopic analyses show that this increase is due to increased emissions from ecosystems (Nisbet et al., 2016; Kirschke et al., 2013). Northern high latitudes wetlands have substantial potential in affecting atmospheric CH4 concentration, given the extensive carbon stored in their soils (Hugelius et al., 2014), and their rate of warming double the global mean (Achberger et al., 2011). However, it remains difficult to predict or attribute changes in atmospheric CH4 concentration to increased emissions from any specific ecosystems, given the sparse baseline CH4 flux estimates available from wetlands, particularly from northern high latitudes.
Here we show that soil freezing in the fall is occurring 1.4 days year-1 later over the last decade across a variety of sites in the North Slope of Alaska, resulting in a longer “zero-curtain” (period when the soil temperature hovers around zero, Outcalt et al., 1990, Hinkel et al., 2001)). Methane emissions across 14 site-years from five sites in the North Slope of Alaska remained consistently higher during the zero curtain then after the complete soil freezing. This later soil freezing was associated with the fall atmospheric CH4 enhancement observed across the North Slope of Alaska over the last 10 years. The consistently higher CH4 emission rates before soil freeing, suggests that warming, and later soil freezing could explain some of the increased in the fall atmospheric CH4 concentration.
Associated Project(s):
Poster Location ID: 75
Session Assigned: Carbon Dynamics
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