01609nas a2200157   4500008004100000022001400041245012700055210007100182260001200253520103400265100002401299700002501323700002401348700002101372856005801393       2021                        eng d  a0885-608700aLong‐term shifts in feedbacks among glacier surface change, melt generation, and runoff, McMurdo Dry Valleys, Antarctica0 aLong‐term shifts in feedbacks among glacier surface change melt   c07/20213 a<p>Glaciers of the McMurdo Dry Valleys (MDVs) Antarctica are the main source of streamflow in this polar desert. Because summer air temperatures hover near 0&deg;C small changes in the energy balance strongly affect meltwater generation. Here we demonstrate that increased surface roughness, which alters the turbulent transfer of energy between the ice surface and atmosphere, yields a detectable increase in meltwater runoff. At low elevations on the glaciers, basin-like topography became significantly rougher over 13&thinsp;years between repeat lidar surveys, yielding greater melt. In contrast, the smoother ice at higher elevation exhibited no detectable change in roughness. We pose a conceptual model of the cycle of glacier surface change as a result of climate forcing whereby glacier surfaces transition from being dominated by sublimation to becoming increasingly melt-dominated, which is reversible under prolonged cool periods. This research advances our understanding of warm season effects on polar glaciers.</p>1 aBergstrom, Anna, J.1 aGooseff, Michael, N.1 aFountain, Andrew, G1 aHoffman, Matthew  uhttps://onlinelibrary.wiley.com/doi/10.1002/hyp.14292