This dataset contains sea-air methane flux data from January 2019 to March 2021 measured using a Picarro G2311-f greenhouse gas analyser onboard RRS James Clark Ross, in the Southern Ocean, Arctic Ocean and Atlantic Ocean. The fluxes are 2 hour averaged and have been filtered based on wind direction to data corresponding to wind coming from behind the ship to remove sources of pollution from the ship stack. Limit of detection for the flux data are calculated for each cruise by multiplying the standard deviation of the random noise by three. This work was supported by the Natural Environment Research Council and the ARIES Doctoral Training Partnership (grant no. NE/S007334/1). Royal Holloway, University of London was funded by NERC through grants NE/V000780/1 and NE/N016211/1. Anna E. Jones and Katrin Linse were part of the British Antarctic Survey Polar Science for Planet Earth Programme funded by the Natural Environment Research Council (NERC) [NC-Science]. The measurements from the Royal Research Ship James Clark Ross (JCR) were principally supported by the UK Natural Environment Research Council''s ORCHESTRA project (Grant No. NE/N018095/1). The Picarro analyser was funded by the European Space Agency funding (ESA AMT4OceanSatFlux project, Grant No. 4000125730/18/NL/FF/gp). This work further contributes to the NERC MOYA project (Grant No. NE/N015932/1).

Data on CO2 and CH4 exchange rates between soil and atmosphere, soil temperatures, bacterial 16S ribosomal RNA genes, fungal internal transcribed spacer 2 (ITS2) copies and the relative abundances of the 40 most abundant bacterial taxa in the 48 plots of a soil warming and irrigation experiment on Svalbard in the High Arctic. On 2014-09-10, a soil warming and irrigation experiment was set up at Kongsfjordneset on the Brogger Peninsula, Svalbard. Warming was applied continuously with open top chambers and the irrigation treatment was applied in mid-late June and late August each year. Greenhouse gas exchange between the soil and atmosphere was measured on 2018-08-23 and 2018-08-26. At this time, soil samples were taken for DNA analyses and the amount of bacterial and fungal DNA present in soil was measured. The 40 most frequent bacterial operational taxonomic units were also determined. This project was funded by UK Natural Environment Research Council (core funding to the British Antarctic Survey), the Danish National Research Foundation (CENPERM DNRF100) and Seoul National University.