The National Science Foundation provided support to the American Geophysical Union (AGU) to engage its relevant community and help clarify the need for a Near-Surface Geophysics (NSG) Center and identify how it could advance key science questions, provide benefits for society, and develop the geophysical workforce of the future. This report synthesizes the broad input from the community. The listed authors represent the Steering Committee, led by Sarah Kruse and Xavier Comas, and AGU staff leads. They were responsible for most of the editing and connective writing. The major conclusions are: ● The capability and importance of NSG is expanding rapidly, and NSG is providing key science and knowledge to many specific scientific challenges in diverse disciplines–from ecology and anthropology to hydrology, oceanography, cryosphere science, soil and critical zone science, and more. ● This has been thanks to diverse new instruments and approaches, expanded monitoring, improved resolution, interoperable data sets, and new computing power and approaches, among other developments. ● As a result, advancing NSG is critical to addressing many societal challenges at local to global scales. Human society depends on and interacts with the NSG environment in deep and diverse ways at all scales. ● Despite these developments, integration of NSG approaches and awareness of these across related disciplines are not nearly robust enough for these needs. ● Major challenges include providing equipment and training around its use, developing and deploying new equipment and sensors, developing interoperable data, and developing computation techniques. ● In particular, educating both current researchers and developing an NSG-enabled workforce is a major challenge. ● Integrating education with societal and scientific challenges provides a great opportunity and means to expand inclusivity and diversity in the Earth sciences and to address climate justice and equity challenges. ● Thus there was a strong consensus for support of an NSG Center designed to address these challenges and needs and to foster convergent science, provide broad and hands-on educational training, and engage communities and the public meaningfully. ● We were not charged with envisioning the specific model for a Center—and indeed emphasized that the term “Center” was generic and did not necessarily imply that these efforts were envisioned to be in one location–but note that NSF is supporting important complementary facilities include the new EarthScope Consortium combining IRIS and UNAVCO, NCALM, and CTEMPS. ● In sum, we strongly encourage the NSF to take the next step in considering the best implementation model for a NSG Center that addresses these needs, enables these opportunities, and leverages and complements existing efforts.

Methane (CH4) emissions from climate-sensitive ecosystems within the northern permafrost region represent a large but highly uncertain source, with current estimates spanning a factor of seven (11 – 75 Tg CH4 yr-1). Accelerating permafrost thaw threatens significant increases in pan-Arctic CH4 emissions, amplifying the permafrost carbon feedback. We used airborne imaging spectroscopy with meter-scale spatial resolution and broad coverage to identify a previously undiscovered CH4 hotspot adjacent to an intensively studied thermokarst lake in interior Alaska. Hotspot emissions were confined to < 1% of the 10 ha study area. Ground-based chamber measurements confirmed average daily fluxes of 1,170 mg CH4 m-2 d-1, with extreme daily maxima up to 24,200 mg CH4 m-2 d-1. Ground-based geophysics measurements revealed thawed permafrost at and directly beneath the CH4 hotspot, extending to a depth of ~15 m, indicating that the intense CH4 emissions likely originated from recently thawed permafrost. Emissions from the hotspot accounted for ~40% of total diffusive CH4 emissions from the entire study area. Combining these results with hotspot statistics from our 70,000 km2 airborne survey across Alaska and northwestern Canada, we estimate that terrestrial thermokarst hotspots currently emit 1.1 (0.1 – 5.2) Tg CH4 yr-1, or roughly 4% of the annual pan-Arctic wetland budget from just 0.01% of the northern permafrost land area. Our results suggest that significant proportions of pan-Arctic CH4 emissions originate from disproportionately small areas of previously undetermined thermokarst emissions hotspots, and that pan-Arctic CH4 emissions may increase non-linearly as thermokarst processes increase under a warming climate.