The transport of oceanic heat towards the Antarctic continental margin is central to the mass balance of the Antarctic Ice Sheet. Recent modeling efforts challenge our view on where and how the on-shelf heat flux occurs, suggesting that it is largest where dense shelf waters cascade down the continental slope. Here we provide observational evidence supporting this claim.
View Article and Find Full Text PDFThwaites Glacier is one of the fastest-changing ice-ocean systems in Antarctica. Much of the ice sheet within the catchment of Thwaites Glacier is grounded below sea level on bedrock that deepens inland, making it susceptible to rapid and irreversible ice loss that could raise the global sea level by more than half a metre. The rate and extent of ice loss, and whether it proceeds irreversibly, are set by the ocean conditions and basal melting within the grounding-zone region where Thwaites Glacier first goes afloat, both of which are largely unknown.
View Article and Find Full Text PDFSubglacial hydrologic systems regulate ice sheet flow, causing acceleration or deceleration, depending on hydraulic efficiency and the rate at which surface meltwater is delivered to the bed. Because these systems are rarely observed, ice sheet basal drainage represents a poorly integrated and uncertain component of models used to predict sea level changes. Here, we report radar-derived basal melt rates and unexpectedly warm subglacial conditions beneath a large Greenlandic outlet glacier.
View Article and Find Full Text PDFFloating ice shelves are the Achilles' heel of the Antarctic Ice Sheet. They limit Antarctica's contribution to global sea level rise, yet they can be rapidly melted from beneath by a warming ocean. At Filchner-Ronne Ice Shelf, a decline in sea ice formation may increase basal melt rates and accelerate marine ice sheet mass loss within this century.
View Article and Find Full Text PDFA set of collocated, in situ oceanographic and glaciological measurements from Petermann Gletscher Ice Shelf, Greenland, provides insights into the dynamics of under-ice flow driving basal melting. At a site 16 km seaward of the grounding line within a longitudinal basal channel, two conductivity-temperature (CT) sensors beneath the ice base and a phase-sensitive radar on the ice surface were used to monitor the coupled ice shelf-ocean system. A 6 month time series spanning 23 August 2015 to 12 February 2016 exhibited two distinct periods of ice-ocean interactions.
View Article and Find Full Text PDFMass loss from the Antarctic ice sheet, Earth's largest freshwater reservoir, results directly in global sea-level rise and Southern Ocean freshening. Observational and modeling studies have demonstrated that ice shelf basal melting, resulting from the inflow of warm water onto the Antarctic continental shelf, plays a key role in the ice sheet's mass balance. In recent decades, warm ocean-cryosphere interaction in the Amundsen and Bellingshausen seas has received a great deal of attention.
View Article and Find Full Text PDFSouthern Ocean ecosystems are under pressure from resource exploitation and climate change. Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale. Here, using assemblage-level tracking of marine predators, we identify AESs for this globally important region and assess current threats and protection levels.
View Article and Find Full Text PDFThe Southern Ocean exerts a major influence on the mass balance of the Antarctic Ice Sheet, either indirectly, by its influence on air temperatures and winds, or directly, mostly through its effects on ice shelves. How much melting the ocean causes depends on the temperature of the water, which in turn is controlled by the combination of the thermal structure of the surrounding ocean and local ocean circulation, which in turn is determined largely by winds and bathymetry. As climate warms and atmospheric circulation changes, there will be follow-on changes in the ocean circulation and temperature.
View Article and Find Full Text PDFThe Retrospective Analysis of Antarctic Tracking Data (RAATD) is a Scientific Committee for Antarctic Research project led jointly by the Expert Groups on Birds and Marine Mammals and Antarctic Biodiversity Informatics, and endorsed by the Commission for the Conservation of Antarctic Marine Living Resources. RAATD consolidated tracking data for multiple species of Antarctic meso- and top-predators to identify Areas of Ecological Significance. These datasets and accompanying syntheses provide a greater understanding of fundamental ecosystem processes in the Southern Ocean, support modelling of predator distributions under future climate scenarios and create inputs that can be incorporated into decision making processes by management authorities.
View Article and Find Full Text PDFIncreasing ocean and air temperatures have contributed to the removal of floating ice shelves from several Greenland outlet glaciers; however, the specific contribution of these external forcings remains poorly understood. Here we use atmospheric, oceanographic, and glaciological time series data from the ice shelf of Petermann Gletscher, NW Greenland to quantify the forcing of the ocean and atmosphere on the ice shelf at a site ~16 km from the grounding line within a large sub-ice-shelf channel. Basal melt rates here indicate a strong seasonality, rising from a winter mean of 2 m yr to a maximum of 80 m yr during the summer melt season.
View Article and Find Full Text PDFThe overturning circulation of the global ocean is critically shaped by deep-ocean mixing, which transforms cold waters sinking at high latitudes into warmer, shallower waters. The effectiveness of mixing in driving this transformation is jointly set by two factors: the intensity of turbulence near topography and the rate at which well-mixed boundary waters are exchanged with the stratified ocean interior. Here, we use innovative observations of a major branch of the overturning circulation-an abyssal boundary current in the Southern Ocean-to identify a previously undocumented mixing mechanism, by which deep-ocean waters are efficiently laundered through intensified near-boundary turbulence and boundary-interior exchange.
View Article and Find Full Text PDFJ Public Health Manag Pract
June 2018
Community health workers (CHWs) have significant potential to contribute to public health in the United States by promoting disaster preparedness, speeding postdisaster recovery, and building disaster resilience in their communities. To maximize this potential, however, they must undergo rigorous and relevant training. As part of the Gulf Region Health Outreach Program, an appropriate curriculum was developed and delivered in several training sessions conducted from 2013 to 2016.
View Article and Find Full Text PDFOceanography (Wash D C)
December 2016
Calving of glacial ice into the ocean from the Greenland Ice Sheet is an important component of global sea level rise. The calving process itself is relatively poorly observed, understood, and modeled; as such, it represents a bottleneck in improving future global sea level estimates in climate models. We organized a pilot project to observe the calving process at Helheim Glacier in East Greenland in an effort to better understand it.
View Article and Find Full Text PDFHauling out is an essential component of pinniped life-history. Haul-out behaviour may be affected by biological (e.g.
View Article and Find Full Text PDFPurpose/objectives: To explore differences in cancer risk knowledge and colorectal cancer (CRC) knowledge among adults in Alabama.
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Research Approach: Telephone interviews were conducted using an 80-item questionnaire that included 14 demographic questions and 26 general questions regarding healthcare quality, sources of health-related information, and cancer fears and risk factors.
Objectives: To ascertain barriers to colorectal cancer screening in an environment of changing recommendations, payment structures, and information access, and to develop strategies for overcoming these barriers by undertaking a population survey of colorectal cancer (CRC) screening knowledge and attitudes in Alabama.
Methods: An 80-item questionnaire focused on cancer screening, specifically CRC screening, was developed and pretested. A random sample of Alabama residents was generated using random-digit dial methods and interviews of 615 participants aged 50 and older were conducted in March 2012 and April 2012.
In order to inform efforts to increase screening rates for colorectal cancer (CRC), we conducted a survey of Alabama primary care physicians regarding CRC screening practices, educational preferences, and perceptions of obstacles to screening. A mail survey of 2,378 Alabama physicians in Family Medicine, Internal Medicine, and Obstetrics & Gynecology was conducted. Many physicians are not fully up-to-date with current CRC screening practices that could improve patient compliance with screening guidelines.
View Article and Find Full Text PDFObjective: To evaluate the utility of offering physicians electronic options as alternatives to completing mail questionnaires.
Data Source: A survey of colorectal cancer screening practices of Alabama primary care physicians, conducted May-June 2010.
Study Design: In the follow-up to a mail questionnaire, physicians were offered options of completing surveys by telephone, fax, email, or online.