Antarctic offshore polynyas linked to Southern Hemisphere climate anomalies.

Offshore Antarctic polynyas-large openings in the winter sea ice cover-are thought to be maintained by a rapid ventilation of deep-ocean heat through convective mixing. These rare phenomena may alter abyssal properties and circulation, yet their formation mechanisms are not well understood. Here we demonstrate that concurrent upper-ocean preconditioning and meteorological perturbations are responsible for the appearance of polynyas in the Weddell Sea region of the Southern Ocean. Autonomous profiling float observations-collected in 2016 and 2017 during the largest polynyas to form near the Maud Rise seamount since 1976-reveal that the polynyas were initiated and modulated by the passage of severe storms, and that intense heat loss drove deep overturning within them. Wind-driven upwelling of record strength weakened haline stratification in the upper ocean, thus favouring destabilization in 2016 and 2017. We show that previous Weddell polynyas probably developed under similarly anomalous conditions, which are associated with a mode of Southern Hemisphere climate variability that is predicted to strengthen as a result of anthropogenic climate change.

High Concentrations of Ozone Air Pollution on Mount Everest: Health Implications for Sherpa Communities and Mountaineers.

Semple, John L., G.W. Kent Moore, Petros Koutrakis, Jack M. Wolfson, Paolo Cristofanelli, and Paolo Bonasoni. High concentrations of ozone air pollution on Mount Everest: health implications for Sherpa communities and mountaineers. High Alt Med Biol. 17:365-369, 2016.-Introduction: Populations in remote mountain regions are increasingly vulnerable to multiple climate mechanisms that influence levels of air pollution. Few studies have reported on climate-sensitive health outcomes unique to high altitude ecosystems. In this study, we report on the discovery of high-surface ozone concentrations and the potential impact on health outcomes on Mount Everest and the high Himalaya. MATERIALS AND METHODS: Surface ozone measurements were collected during ascending transects in the Mount Everest region of Nepal with passive nitrite-coated Ogawa filter samplers to obtain 8-hour personal exposures (2860-5364 m asl). In addition, the Nepal Climate Observatory-Pyramid, a GAW-WMO Global Station sited in the Khumbu Valley (5079 m asl), collected ozone mixing ratios with photometric gas analyzer. RESULTS: Surface ozone measurements increased with altitude with concentrations that exceed 100 ppb (8-hour exposure). Highest values were during the spring season and the result of diverse contributions: hemispheric background values, the descent of ozone-rich stratospheric air, and the transport of tropospheric pollutants occurring at different spatial scales. DISCUSSION: Multiple climate factors, including descending stratospheric ozone and imported anthropogenic air masses from the Indo-Gangetic Plain, contribute to ambient ozone exposure levels in the vicinity of Mount Everest that are similar to if not higher than those reported in industrialized cities.

A tale of two climbers: hypothermia, death, and survival on Mount Everest.

Hypothermia is an acknowledged risk for those who venture into high altitude regions. There is however little quantitative information on this risk that can be used to implement mitigation strategies. Here we provide an analysis of the meteorological and hypothermic risk parameters, wind chill temperature, and facial frostbite time, during the spring 2006 Mount Everest climbing season. This season was marked by two high profile events where a solo climber was forced to spend the night in highly exposed conditions near the summit. One climber survived, while the other did not. Although this retrospective examination of two individual cases has admittedly a small sample size, and there are other factors that undoubtedly contributed to the difference in outcomes, we show that wind chill temperature and facial frostbite time experienced by the two climbers were dramatically different. In particular, the climber who did not survive experienced conditions that were approximately one standard deviation more severe that usual for that time of the year; while the climber who survived experienced conditions that were approximately one standard deviation less severe then usual. This suggests that the environmental conditions associated with hypothermia played an important role in the outcomes. This report confirms the importance of providing quantitative guidance to climbers as the risk of hypothermia on high mountains.