Ice patches have implications for landscape and ecosystem dynamics in polar deserts, however, the understanding of the driving factors that control their spatio-temporal variability is limited. This study aims to assess the seasonal and long-term evolution of ice patches on Ward Hunt Island (WHI; 83°N, Canadian High Arctic) based on field measurements of surface mass and energy balance. Results show that mass gains of the ice patch systems occur mostly through drifting snow, making them highly linked to the topography as well as the frequency and magnitude of wind events. Summer ablation is primarily driven by net radiation, but the short-term variability in melt rate is driven by sensible heat fluxes. The highest ablation rates occur during the passage of warm fronts that combine strong winds and mild temperatures. Conversely, foggy days reduce fluxes of solar radiation and sensible heat to the snow/ice surface, thereby suppressing ablation. Ice patches are less climate-sensitive than other cryospheric elements due to a feedback between snow accumulation and topography, however, summer ablation is strongly influenced by micrometeorology. Model projections of these factors suggest that conditions will become critical for preserving ice patches at WHI and along the northern coast of Ellesmere Island as early as in the next decades.

In polar deserts, depth hoar (hereinafter: DH) growth is not systematic unlike on tundra and this is critical for snowpack properties. Here, we address the spatio-temporal variability of the DH layer in the polar desert at two sites in the Canadian High Arctic: Ward Hunt Island (83° N) and Resolute Bay (75° N). Our data show that, over humid areas, DH represented a larger fraction of the snowpack and was characterized by lower density and coarser crystals than over dry gravelly areas. Increased soil moisture extends the zero-curtain period during freeze-up, leading to stronger temperature gradients in the snowpack and greater kinetic metamorphism. Our results also demonstrate that the large inter-annual variability in DH is primarily driven by wind conditions in the fall since this key variable controls the initial snow density and snow onset date. These strong controls exerted by soil moisture and meteorological conditions on DH growth in polar deserts highlight the possibility of major changes in polar snowpacks physical properties in response to the rapid climate and environmental changes currently affecting these regions.

Microbial mats are common in polar streams and often dominate benthic biomass. Climate change may be enhancing the variability of stream flows in the Antarctic, but so far studies investigating mat responses to disturbance have been limited in this region. Mat regrowth was evaluated following disturbance by experimentally scouring rocks from an ephemeral McMurdo Dry Valley stream over two summers (2001–02 and 2012–13). Mats were sampled at the beginning and resampled at the end of the flow season. In 2012–13, mats were additionally resampled mid-season along with previously undisturbed controls. In 2001–02 rocks regained 47% of chlorophyll a and 40% of ash-free dry mass by the end of the summer, while in 2012–13 rocks regrew 18% and 27%, respectively. Mat stoichiometry differed between summers, and reflected differences in biomass and discharge. Oscillatoria spp. were greatest on scoured rocks and Phormidium spp. on undisturbed rocks. Small diatoms Humidophila and Fistulifera spp. increased throughout the summer in all mats, with the latter more abundant in scoured communities. Collectively, these data suggest that mats are variable intra-annually, responsive to hydrology and require multiple summers to regrow initial biomass once lost. These results will aid the interpretation of long-term data, as well as inform Antarctic Specially Managed Area protocols.