A critical question for assessing global greenhouse gas budgets is how much of the methane that escapes from seafloor cold seep sites to the overlying water column eventually crosses the sea-air interface and reaches the atmosphere. The issue is particularly important in Arctic Ocean waters since rapid warming there increases the likelihood that gas hydrate--an ice-like form of methane and water stable at particular pressure and temperature conditions within marine sediments--will break down and release its methane to the overlying ocean. Some researchers have even proposed the possibility of an Arctic methane catastrophe characterized by wholesale breakdown of gas hydrates in marine sediments and release of the methane to the atmosphere as climate warms. This dataset collected on the West Spitsbergen margin during U.S. Geological Survey Coastal and Marine Geology Program Field Activity 2014-013-FA, which was carried out in conjunction with the University of Tromso and the GEOMAR Helmholtz Centre for Ocean Research Kiel on the R/V Helmer Hanssen, records 30-second-gridded methane and carbon dioxide concentrations in near-surface seawater and the atmospheric marine boundary layer, the carbon-13 isotopic composition of methane and carbon dioxide in the near-surface waters, and also environmental parameters (e.g., seawater salinity, wind speed, water and air temperatures). The results of calculations required to determine the sea-air flux of methane and carbon dioxide are also provided.

Determining how much methane and carbon dioxide cross the sea-air interface is critical when assessing marine greenhouse gas fluxes. This assessment is particularly important on Arctic Ocean continental margins, where rapid climate change is thawing glacial ice and permafrost; reducing sea ice cover; and changing water temperatures, salinities, nutrient loads, and ocean currents. This dataset was collected in the Sherard Osborn Fjord and adjacent areas of the Nares Strait and Lincoln Sea on the northern Greenland margin during the 2019 Ryder Expedition (known as SWEDARCTIC Ryder 2019), which is also identified as U.S. Geological Survey (USGS) Coastal and Marine Hazards and Resources Program Field Activity 2019-042-FA. The University of Stockholm led the expedition aboard the Swedish icebreaker Oden (IB Oden), in collaboration with the University of New Hampshire and the USGS. The dataset contains 30-second interpolated methane and carbon dioxide concentrations in near-surface seawater and the atmospheric marine boundary layer and provides the calculations used to determine the sea-air flux. The dataset also contains environmental data, including seawater salinity, wind speed, water and air temperatures, water depth, seawater pH, seawater dissolved oxygen, seawater fluorescent dissolved organic matter, seawater oxidation-reduction potential, seawater phycoerythrin, and seawater chlorophyll.

Determining how much methane and carbon dioxide cross the sea-air interface is critical when assessing marine greenhouse gas fluxes. This assessment is particularly important on Arctic Ocean continental margins, where rapid climate change is thawing glacial ice and permafrost; reducing sea ice cover; and changing water temperatures, salinities, nutrient loads, and ocean currents. This dataset was collected in the Sherard Osborn Fjord and adjacent areas of the Nares Strait and Lincoln Sea on the northern Greenland margin during the 2019 Ryder Expedition (known as SWEDARCTIC Ryder 2019), which is also identified as U.S. Geological Survey (USGS) Coastal and Marine Hazards and Resources Program Field Activity 2019-042-FA. The University of Stockholm led the expedition aboard the Swedish icebreaker Oden (IB Oden), in collaboration with the University of New Hampshire and the USGS. The dataset contains 30-second interpolated methane and carbon dioxide concentrations in near-surface seawater and the atmospheric marine boundary layer and provides the calculations used to determine the sea-air flux. The dataset also contains environmental data, including seawater salinity, wind speed, water and air temperatures, water depth, seawater pH, seawater dissolved oxygen, seawater fluorescent dissolved organic matter, seawater oxidation-reduction potential, seawater phycoerythrin, and seawater chlorophyll.

We present methane data from along the coast of Barter Island, Alaska, collected with an Unmanned Aerial System and an off-the-shelf, cost-effective methane sensor. The data were collected on September 3 and September 5, 2017, as part of a larger Arctic coastal erosion investigation study by the U.S. Geological Survey (USGS). The data contain latitude, longitude and CH4 (ppm), and are presented as tab-delimited text files that have been zipped into one file. In addition, we have included one file of comparative data from Barrow, Alaska that were collected by the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division from 1986-2017 as a courtesy to users. The three datasets together accompany Oberle, F.K.J., Gibbs, A.E., Richmond, B.M., Erikson, L.H., Waldrop, M.P., and Swarzenski, P.W., 2019, Towards determining spatial methane distribution on Arctic permafrost bluffs with an unmanned aerial system: SN Applied Sciences, https://doi.org/10.1007/s42452-019-0242-9.

This dataset provides an upscaled estimate of Boreal-Arctic wetland CH4 emissions at a weekly time scale from 2002 to 2021 at 0.5 by 0.5-degree spatial resolution. Ground truth data on wetland CH4 emissions from eddy covariance towers (139 site years) and chambers (168 site years) were used to train and validate a causality-guided machine learning model. The trained model was then used to estimate CH4 emissions at grid cells that have wetlands and located above 44 degrees north. The data are provided in netCDF format.

This dataset contains a combined globally mapped estimate of the air-sea exchange of carbon dioxide (CO2) based on Surface Ocean CO2 Atlas Database (SOCAT) partial pressure of CO2 (pCO2) and calculated pCO2 from Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) biogeochemistry floats from 1982 to 2017. The pCO2 fields were created using a 2-step neural network technique. In a first step, the global ocean is divided into 16 biogeochemical provinces using a self-organizing map. In a second step, the non-linear relationship between variables known to drive the surface ocean carbon system and gridded observations from the SOCAT dataset (Bakker et al., 2016) starting in 1982 in various combinations with calculated pCO2 from biogeochemical ARGO floats starting in 2014 from the SOCCOM project (Johnson et al., 2017) is reconstructed using a feed-forward neural network within each province separately. The final product is then produced by projecting these driving variables, i.e., surface temperature, chlorophyll, mixed layer depth, and atmospheric CO2 onto oceanic pCO2 using these non-linear relationships. This results in monthly pCO2 fields at 1°x1° resolution covering the entire globe with the exception of the Arctic Ocean and few marginal seas. The air-sea CO2 flux is then computed using a standard bulk formula.

A watershed in the coastal Canadian Arctic was sampled for dissolved carbon dioxide and methane concentration and stable carbon (carbon-13) isotopes to trace the transport, production, and consumption of carbon dioxide and methane during the spring thaw across a lake to bay transect. Two field campaigns were conducted in June 2022 and June-July 2023 out of the Canadian High Arctic Research Station (CHARS) in Cambridge Bay, Nunavut, Canada. Gas samples were collected via headspace extraction and transported back to the U.S. Geological Survey (USGS) Woods Hole Coastal and Marine Science Center (WHCMSC), where they were analyzed utilizing the USGS Automated Sample Introduction Module (AutoSIM) interfaced to a Picarro G2201-i CRDS (Cavity Ring-Down Spectrometer) to measure concentrations and stable carbon isotope ratios of methane and carbon dioxide. Field sampling was carried out by researchers from the Woods Hole Oceanographic Institution.

This dataset includes Surface underway, chemical, meteorological and physical data collected from POLARSTERN in the Arctic Ocean, Barents Sea, English Channel, Laptev (or Nordenskjold) Sea, North Atlantic Ocean, North Greenland Sea, North Sea, Norwegian Sea, South Atlantic Ocean and Southern Oceans (> 60 degrees South) from 2012-01-08 to 2012-10-06. These data include BAROMETRIC PRESSURE, Partial pressure (or fugacity) of carbon dioxide - atmosphere, Partial pressure (or fugacity) of carbon dioxide - water, SALINITY, SEA SURFACE TEMPERATURE, WIND DIRECTION and WIND SPEED. The instruments used to collect these data include Carbon dioxide (CO2) gas analyzer. These data were collected by Mario Hoppema of Alfred Wegener Institute for Polar and Marine Research (AWI), Steven M. A. C. van Heuven of Groningen University, and Elizabeth M. Jones of NIOZ as part of the VOS_Polarstern_2012 dataset. CDIAC associated the following cruise ID(s) with this dataset: 06AQ20120108