Future glacial lakes in High Mountain Asia: an inventory and assessment of hazard potential from surrounding slopes

Bedrock overdeepenings exposed by continued glacial retreat can store precipitation and meltwater, potentially leading to the formation of new proglacial lakes. These lakes may pose threats of glacial lake outburst floods (GLOFs) in high mountain areas, particularly if new lakes form in geomorphological setups prone to triggering events such as landslides or moraine collapses. We present the first complete inventory for future glacial lakes in High Mountain Asia by computing the subglacial bedrock for ~100 000 glaciers and estimating overdeepening area, volume and impact hazard for the larger potential lakes. We detect 25 285 overdeepenings larger than 104 m2 with a volume of 99.1 ± 28.6 km3 covering an area of 2683 ± 773.8 km2. For the 2700 overdeepenings larger than 105 m2, we assess the lake predisposition for mass-movement impacts that could trigger a GLOF by estimating the hazard of material detaching from surrounding slopes. Our findings indicate a shift in lake area, volume and GLOF hazard from the southwestern Himalayan region toward the Karakoram. The results of this study can be used for anticipating emerging threats and potentials connected to glacial lakes and as a basis for further studies at suspected GLOF hazard hotspots.Peer Reviewe

Projected 21st-Century Glacial Lake Evolution in High Mountain Asia

In High Mountain Asia (HMA), rising temperatures and retreating glaciers are leading to the formation of new glacial lakes and the expansion of existing ones. The sudden release of water from such lakes can lead to devastating glacial lake outburst floods (GLOF) threatening people and infrastructure for many kilometers downstream. Therefore, information on future glacial lakes, e.g., their location, area and volume as well as the timing of their development, is vital for sustainable development of settlements and infrastructures. In this study, we present comprehensive estimates for future glacial lake development in HMA with unprecedented temporal resolution. We rely on an ensemble of fifteen global climate models using the newest CMIP6 data and employ a set of four Shared Socioeconomic Pathway (SSP) scenarios. With the Open Global Glacier Model (OGGM), we use a modeling framework that explicitly simulates glacier dynamics in order to model glacier change until 2100 and estimate the formation period for each of the 2,700 largest future glacial lakes (>0.1 km2) in HMA. We estimate the glacial lake area in the entire region to grow by 474 ± 121 km2 for SSP126 and 833 ± 148 km2 for SSP585. Following recent estimates of currently existing glacial lakes (>0.1 km2), this would constitute an increase in lake area of ∼120–∼210% in 2100 compared to 2018. The lake volume is expected to increase by 22.8 ± 6.7 km3 for SSP126 and 39.7 ± 7.7 km3 for SSP585. This range includes a drastic tenfold increase in lake volume, from estimated 3.9 km3 in 2018 to 43.6 ± 7.7 km3 in 2100. However, there is a considerable spread between total and relative increase in glacial lake area and volume for different sub-regions of High Mountain Asia. As both, lake area and lake volume, could to lead to an increase in GLOF risk, the results emphasize the urgent need for more localized, in-depth studies at especially vulnerable locations in order to enable local communities to adapt to emerging challenges, to implement risk minimization measures, and to improve sustainable development in High Mountain Asia.Peer Reviewe

The importance of air temperature as a key parameter to identify climatic processes inside Carlsbad Cavern, New Mexico, USA

The meteorological and climatic conditions in Carlsbad Cavern are very complex. The huge rooms and the large entrance area, in combination with smaller connection tunnels and remote chambers, cause a complexity of different microclimates side by side. As in the case of most others, Carlsbad Cavern is not easy to classify as a barometric or a convective cave system. The objective of this paper is to explain the climate at different positions inside Carlsbad Cavern by evaluating a series of measurements taken during the year 2013. The air temperature will be used as a key parameter for the analysis. We will identify the thermal- or convection-driven influences, as well as some clear barometric effects and underline the importance of air temperature for cave climate research. We will also investigate the influence of the tourist use of the cave, which means the visitors themselves, as well as the elevators, the cafeteria, and the electrical system and lights. Because the analyzed time period includes the time of the government shutdown in 2013, the artificial effects can be identified very easily

Temperature sensing in underground facilities by Raman optical frequency domain reflectometry using fiber-optic communication cables

Gaining information on climatic conditions in subway tunnels is the key to predicting the propagation of smoke or toxic gases in these infrastructures in the case of a fire or a terrorist attack. As anemometer measurements are not economically suitable, the employment of alternative monitoring methods is necessary. High-resolution temperature sensing with Raman optical frequency domain reflectometry (OFDR) using optical communication fiber cables shows great potential as it allows the surveillance of several kilometers of underground transport facilities without the need for installing sensing equipment in the tunnels. This paper presents first results of a study using this approach for monitoring subway tunnels. In the Berlin subway, temperature data gathered from newly installed as well as pre-installed communication cables were evaluated and compared to reference data from temperature loggers. Results are very promising as high correlations between all data can be achieved showing the potential of this approach

A study on thermal dynamics inside Carlsbad Cavern, New Mexico, USA

The climatic conditions of Carlsbad Cavern, New Mexico, are particularly complex. Its variety of large, as well as very narrow chambers, tunnels, and remote areas is the reason for its diversity of microclimates and special climatic features that are the subject of this paper, which can be seen as accompanying the article "The importance of air temperature as a key parameter to identify climatic processes inside Carlsbad Cavern, New Mexico, USA" by Killing-Heinze et al. (this issue). Two studies measured the trends of temperature through much of the cave during March-April 2011 and February 2013. One of the studies also assessed airflow directions using puffs of smoke. The main result was the detection of the flow of cold outside air from the entrance down the floor of the Main Passage and into the Big Room, especially along its west side. Temperatures increased along the route from the entrance to the Big Room, but some locations in the Big Room showed temperature ranges as great as those in the Main Corridor