Growing season, non-growing season and annual CH4 fluxes from temperate, boreal, and Arctic wetlands and uplands, 1974-2016, Northern Hemisphere

Treat, Claire C; Bloom, A Anthony; Marushchak, Maija E

Wetlands are the single largest natural source of atmospheric methane (CH4), a greenhouse gas, and occur extensively in the northern hemisphere. Large discrepancies remain between bottom-up and top-down estimates of northern CH4 emissions. To explore whether these discrepancies are due to poor representation of non-growing season CH4 emissions, we synthesized non-growing season and annual CH4 flux measurements from temperate, boreal, and tundra wetlands and uplands. Median non-growing season wetland emissions ranged from 0.9 g m⁻² in bogs to 5.2 g m⁻² in marshes and were dependent on moisture, vegetation, and permafrost. Annual wetland emissions ranged from 0.9 g m⁻² y⁻¹ in tundra bogs to 78 g m⁻² y⁻¹ in temperate marshes. Uplands varied from CH4 sinks to CH4 sources with a median annual flux of 0.0 ± 0.2 g m⁻² y⁻¹. The measured fraction of annual CH4 emissions during the non-growing season (observed: 13 to 47%) was significantly larger than was predicted by two process-based model ensembles, especially between 40-60º N (modeled: 4 to 17%). Constraining the model ensembles with the measured non-growing fraction increased total non-growing season and annual CH4 emissions. Using this constraint, the modeled non-growing season wetland CH4 flux from >40° north was 6.1 ± 1.5 Tg y⁻¹, three times greater than the non-growing season emissions of the unconstrained model ensemble. The annual wetland CH4 flux was 37 ± 7 Tg y⁻¹ from the data-constrained model ensemble, 25% larger than the unconstrained ensemble. Considering non-growing season processes is critical for accurately estimating CH4 emissions from high latitude ecosystems, and necessary for constraining the role of wetland emissions in a warming climate. This dataset contains the synthesis of measured flux data from the study.

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Contact

Treat, Claire C

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Data and Resources

Additional Info

Field Value
Identifier DOI:10.1594/PANGAEA.886976
Project(s)
Institute Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
Source https://doi.org/10.1594/PANGAEA.886976
Publication Date 2018-02-28
Version 1.0
Product synthesis of measured flux data
Sensor static chambers, automated chambers, eddy covariance, snowpack diffusion methods
Files
  1. Annual CH4 estimates
Variables [Units]
  1. Sort: internet dataset ID
  2. Reference: short study name
  3. MsmtLocation: measurement location within site
  4. Site_Name: Name of site where study was conducted
  5. Ecosystem Type: classification of ecosystem type in paper
  6. WetlandClass: wetland classification
  7. SoilType: organic, mineral, unknown
  8. Measured or estimated annual flux: Method (measurements throughout the year or annual estimated based on empirical data)
  9. Permafrost: permafrost present or absent
  10. Method: chamber, eddy covariance, other
  11. Lat_N: site location, latitude degrees north
  12. Long_E: site longitude, degrees east
  13. Region: name
  14. Biome: biome from Olsson etal
  15. MAAT_C: mean annual temperature
  16. MAAP_mm: mean annual precipitation
  17. WTD_cm: water table depth (+ values=below surface – values are flooding)
  18. pH: measured pH
  19. Soil_Temp_C: reported soil temperature [°C]
  20. MaxALT_cm: maximum measured active layer thickness [cm]
  21. Vegetation_description: vegetation types
  22. Moss_none: no moss at measurement location
  23. Moss_BROWN: brown moss at measurement location
  24. Moss_Sphagnum: sphagnum moss at measurement location
  25. Cyperacae: cyperacae dominant/present/absent in measurement location
  26. Eri_Shrub: Ericaceous shrubs dominant/present/absent in measurement location
  27. Tree: trees dominant/present/absent in measurement location
  28. Timing: notes on when measurements where made
  29. Year: year of measurement
  30. Mean_daily_grow_CH4_mg_CH4_m-2_d-1: mean daily growing season CH4 flux_units
  31. Mean_daily_fluxSD: standard deviation of mean daily growing season flux
  32. GrowingSeasonLength_days: length of growing season used to calculate cumulative growing season CH4 flux from mean daily flux
  33. AnnualFluxMultiplier: calculated from Annual_gCH4_m2_y/SeasonalCH4_gCH4m2
  34. SeasonalCH4_gCH4m2: cumulative growing season CH4 flux
  35. Non-Growing_season_flux_g_CH4_m-2: non-growing season CH4 flux
  36. Annual_gCH4_m2_y: annual CH4 flux
  37. Annual_fluxSD: std deviation of annual flux
  38. RemoveQC: TRUE/FALSE, TRUE if duplicate record, campaign flux, or erroneous flux value (>100x different than median of others reporting).
  39. Notes1: notes
  40. Notes2/Number_from_McGuire_Supp.: more notes
  41. Reference: full reference
Region Northern Hemisphere
Spatial Reference EPSG:4326 WGS 84
Spatial Resolution
Spatial Coverage Latitude 26.383333 to 81.800000, Longitude -162.015333 to 161.350000
Temporal Coverage 1974-2016
Temporal Resolution annual
Format tab delimited text file
Is Supplement To

Treat, CC et al. (2018): Non-growing season methane emissions - a significant component of annual emissions across northern ecosystems. Global Change Biology, 24(8), 3331-3343, https://doi.org/10.1111/gcb.14137
Related to

Dataset extent