Purpose This Commentary is a review and critique of arguments that oppose the desirability and impact of professional collaboration in education. The purpose of this paper is to analyze two recent high-profile reviews of professional development and collaboration. The analysis is informed by a historical typology of five phases of professional collaboration in theory and practice. Design/methodology/approach The Commentary reviews and summarizes selected key texts that represent different phases in the development of advocacy for and research concerning the emergence of professional collaboration. It then critiques the methodology, findings, and recommendations of two key critiques of professional collaboration and development that have been widely disseminated for educators and policymakers. Findings Contrary to the views of its opponents, professional collaboration as a whole has a record of indirect, long term, yet clear and positive effects on teachers and students. Particular kinds of professional collaboration can vary a great deal in quality and impact, however. Short-term collaborative interventions, such as data teams, are often dependent for their success on the prior existence of deeper cultures and processes. These processes and cultures characterize high-performing systems globally. Advocacy for competitive alternatives is based on insufficient evidence. Originality/value Although advocacy for more competition in public school systems is common, high-profile critiques of professional collaboration are relatively new. This paper engages with these critiques from a broader historical perspective, and finds they have serious flaws of reasoning and methodology. Thus far, the critiques provide insufficient warrant for moves toward more competitive systems of schooling and teaching.

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Groundwater flow regimes in the seasonally thawed soils in areas of continuous permafrost are relatively unknown despite their potential role in delivering water, carbon, and nutrients to streams. Using numerical groundwater flow models informed by observations from a headwater catchment in arctic Alaska, United States, we identify several mechanisms that result in substantial surface‐subsurface water exchanges across the land surface during downslope transport and create a primary control on dissolved organic carbon loading to streams and rivers. The models indicate that surface water flowing downslope has a substantial groundwater component due to rapid surface‐subsurface exchanges across a range of hydrologic states, from unsaturated to flooded. Field‐based measurements corroborate the high groundwater contributions, and river dissolved organic carbon concentrations are similar to that of groundwater across large discharge ranges. The persistence of these groundwater contributions in arctic watersheds will influence carbon export to rivers as thaw depth increases in a warmer climate.

The external drivers and internal controls of groundwater flow in the thawed “active layer” above permafrost are poorly constrained because they are dynamic and spatially variable. Understanding these controls is critical because groundwater can supply solutes such as dissolved organic matter to surface water bodies. We calculated steady‐state three‐dimensional suprapermafrost groundwater flow through the active layer using measurements of aquifer geometry, saturated thickness, and hydraulic properties collected from two major landscape types over time within a first‐order Arctic watershed. The depth position and thickness of the saturated zone is the dominant control of groundwater flow variability between sites and during different times of year. The effect of water table depth on groundwater flow dwarfs the effect of thaw depth. In landscapes with low land‐surface slopes (2–4%), a combination of higher water tables and thicker, permeable peat deposits cause relatively constant groundwater flows between the early and late thawed seasons. Landscapes with larger land‐surface slopes (4–10%) have both deeper water tables and thinner peat deposits; here the commonly observed permeability decrease with depth is more pronounced than in flatter areas, and groundwater flows decrease significantly between early and late summer as the water table drops. Groundwater flows are also affected by microtopographic features that retain groundwater that could otherwise be released as the active layer deepens. The dominant sources of groundwater, and thus dissolved organic matter, are likely wet, flatter regions with thick organic layers. This finding informs fluid flow and solute transport dynamics for the present and future Arctic.

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