Heterogeneous melting near the Thwaites Glacier grounding line.

Thwaites Glacier represents 15% of the ice discharge from the West Antarctic Ice Sheet and influences a wider catchment1-3. Because it is grounded below sea level4,5, Thwaites Glacier is thought to be susceptible to runaway retreat triggered at the grounding line (GL) at which the glacier reaches the ocean6,7. Recent ice-flow acceleration2,8 and retreat of the ice front8-10 and GL11,12 indicate that ice loss will continue. The relative impacts of mechanisms underlying recent retreat are however uncertain. Here we show sustained GL retreat from at least 2011 to 2020 and resolve mechanisms of ice-shelf melt at the submetre scale. Our conclusions are based on observations of the Thwaites Eastern Ice Shelf (TEIS) from an underwater vehicle, extending from the GL to 3 km oceanward and from the ice-ocean interface to the sea floor. These observations show a rough ice base above a sea floor sloping upward towards the GL and an ocean cavity in which the warmest water exceeds 2 °C above freezing. Data closest to the ice base show that enhanced melting occurs along sloped surfaces that initiate near the GL and evolve into steep-sided terraces. This pronounced melting along steep ice faces, including in crevasses, produces stratification that suppresses melt along flat interfaces. These data imply that slope-dependent melting sculpts the ice base and acts as an important response to ocean warming.

Channelized ice melting in the ocean boundary layer beneath Pine Island Glacier, Antarctica.

Ice shelves play a key role in the mass balance of the Antarctic ice sheets by buttressing their seaward-flowing outlet glaciers; however, they are exposed to the underlying ocean and may weaken if ocean thermal forcing increases. An expedition to the ice shelf of the remote Pine Island Glacier, a major outlet of the West Antarctic Ice Sheet that has rapidly thinned and accelerated in recent decades, has been completed. Observations from geophysical surveys and long-term oceanographic instruments deployed down bore holes into the ocean cavity reveal a buoyancy-driven boundary layer within a basal channel that melts the channel apex by 0.06 meter per day, with near-zero melt rates along the flanks of the channel. A complex pattern of such channels is visible throughout the Pine Island Glacier shelf.

Gender disparities in tuberculosis: report from a rural DOTS programme in south India.

SETTING: Tiruvallur District, south India. OBJECTIVES: To examine gender differences in tuberculosis among adults aged >14 years with respect to infection and disease prevalence, health care service access, care seeking behaviour, diagnostic delay, convenience of directly observed treatment (DOT), stigma and treatment adherence. METHODS: Data were collected from 1) community survey, 2) self-referred out-patients seeking care at governmental primary health institutions (PHIs), 3) tuberculosis suspects referred for sputum microscopy at PHIs, and 4) tuberculosis patients notified under DOTS. Community survey results were compared with those for patients notified at PHIs. RESULTS: In the community, 66% of males and 57% of females had tuberculosis infection. The prevalence of smear-positive tuberculosis was 568 and 87/100,000, respectively, among males and females. Fewer males than females attended PHIs (68 men for every 100 women). Females constituted 13% of all smear-positive patients detected in the community survey, and 20% of those detected at PHIs (P < 0.05). The probability of notification decreased significantly with age among both males and females. Significantly more females than males felt inhibited discussing their illness with family (21% vs. 14%) and needed to be accompanied for DOT (11% vs. 6%). Males had twice the risk of treatment default than females (19% vs. 8%; P < 0.01). CONCLUSIONS: Despite facing greater stigma and inconvenience, women were more likely than men to access health services, be notified under DOTS and adhere to treatment. Men and elderly patients need additional support to access diagnostic and DOT services.