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This content will become publicly available on May 11, 2019

Title: Increasing Methane Emissions From Natural Land Ecosystems due to Sea-Level Rise

We report atmospheric methane (CH 4) is one of the most important greenhouse gases. However, there is still a large uncertainty in simulating CH 4 emissions from terrestrial ecosystems. Different from modeling studies focusing on response of CH 4 emissions to various environmental changes in land ecosystems, this study analyzed the response of CH 4 emissions to sea-level rise (SLR). To do so, a large-scale surface water routing module was incorporated into an existing CH 4 model. This allowed the model to simulate the effect of SLR on river flows and inland water levels. This study focused on these freshwater systems and did not address saltwater intrusion or coastal wetland impacts. Both the annual maximum inundation extent and CH 4 emissions at the global level showed a steadily growing trend, with an increase of 1.21 × 10 5 km 2 in extent and an increase of 3.13 Tg CH 4/year in CH 4 emissions, in a 22-year SLR experiment from 1993 to 2014. Most of new inundation and methane source areas were located near rivers' deltas and along downstream reaches of rivers. The increase in the inundation extent is primarily influenced by precipitation, channel geomorphic characteristics, and topography of riversidemore » area. The increase of CH 4 emissions due to the SLR is largely determined by the inundation extent, but other factors such as air temperature and carbon storage also play roles. Although the current SLR-induced increases in the inundation extent and CH 4 emissions only accounted for 1.0% and 1.3% of their global totals, these increases contributed 7.0% and 17.3% of the mean annual variability in both, respectively, during the study period. Considering that SLR has a long-term increasing trend, future SLR under a changing climate could play a more important role in global CH 4 emissions.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [4] ;  [5] ; ORCiD logo [6]
  1. Oregon State Univ., Corvallis, OR (United States). Department of Forest Ecosystems and Society
  2. Iowa State University of Science and Technology, Ames IA (United States). Department of Geological and Atmospheric Sciences
  3. Purdue Univ., West Lafayette, IN (United States). Department of Earth, Atmospheric, and Planetary Sciences
  4. Laboratoire d'Etudes du Rayonnement et de la Matière en Astrophysique, CNRS, Observatoire de Paris, Paris (France)
  5. Pacific Northwest National Laboratory, College Park, MD (United States). Joint Global Change Research Institute
  6. Wageningen University, Wageningen (Netherlands). Hydrology and Quantitative Water Management Group
Publication Date:
Report Number(s):
PNNL-SA-130164
Journal ID: ISSN 2169-8953
Grant/Contract Number:
AC05-76RL01830; NNX17AK20G-1555205
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Biogeosciences
Additional Journal Information:
Journal Volume: 123; Journal Issue: 5; Journal ID: ISSN 2169-8953
Publisher:
American Geophysical Union
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; 59 BASIC BIOLOGICAL SCIENCES; methane emission; sea-level rise; modeling
OSTI Identifier:
1457767