An Overview of Physical Risks in the Mt. Everest Region

In April and May 2019, as part of National Geographic and Rolex's Perpetual Planet Everest Expedition, an interdisciplinary scientific effort conducted a suite of research on the mountain and recognized many changing dynamics, including emergent risks resulting from natural and anthropogenic changes to the biological system. In this paper, the diverse research teams highlight risks to ecosystem and human health, geologic hazards, and changing climbing conditions that may affect the local community, climbers, and trekkers in the future. This Primer brings together perspectives from across the atmospheric, biological, geological, and health sciences to better understand emergent risks on Mt. Everest and in the Khumbu region. Understanding these risks is critical for the ~10,000 people living in the Khumbu region, the thousands of visiting trekkers, and the hundreds of climbers who attempt to summit each year

Can shells of freshwater mussels (Unionidae) be used to estimate low summer discharge of rivers and associated droughts?

This paper examines if shell oxygen isotope ratios (d18Oar) of Unio sp. can be used as a proxy of past discharge of the river Meuse. The proxy was developed from a modern dataset for the reference time interval 1997–2007, which showed a logarithmic relationship between discharge and measured water oxygen isotope ratios(d18Ow). To test this relationship for past time intervals,d18Oar values were measured in the aragonite of the growth increments of four Unio sp. shells; two from a relatively wet period and two from a very dry time interval (1910–1918 and 1969–1977, respectively). Shell d18Oar records were converted into d18Ow values using existing water temperature records. Summer d18Ow values, reconstructed from d18Oar of 1910–1918, showed a similar range as the summer d18Ow values for the reference time interval 1997–2007, whilst summer reconstructed d18Ow values for the time interval 1969–1977 were anomalously high. These high d18Ow values suggest that the river Meuse experienced severe summer droughts during the latter time interval. d18Ow values were then applied to calculate discharge values. It was attempted to estimate discharge from the reconstructed d18Ow values using the logarithmic relationship between d18Ow and discharge. A comparison of the calculated summer discharge results with observed discharge data showed that Meuse low-discharge events below a threshold value of 6 m3/s can be detected in the reconstructed d18Ow records, but true quantification remains problematic

Pushing climate change science to the roof of the world

The National Geographic and Rolex Perpetual Planet Everest Expedition is a multidisciplinary project dedicated to understanding climate change and its impacts, improving climate predictions, and providing a framework for future research in mountain environments. This issue of One Earth offers a first look at the science emerging from the expedition