Abstract. To make first-order estimates of the probability of moraine-dammed lake outburst flood (MDLOF) and prioritize the probabilities of breaching posed by potentially dangerous moraine-dammed lakes (PDMDLs) in the Chinese Himalayas, an objective approach is presented. We first select five indicators to identify PDMDLs according to four predesigned criteria. The climatic background was regarded as the climatic precondition of the moraine-dam failure, and under different climatic preconditions, we distinguish the trigger mechanisms of MDLOFs and subdivide them into 17 possible breach modes, with each mode having three or four components; we combined the precondition, modes and components to construct a decision-making tree of moraine-dam failure. Conversion guidelines were established so as to quantify the probabilities of components of a breach mode employing the historic performance method combined with expert knowledge and experience. The region of the Chinese Himalayas was chosen as a study area where there have been frequent MDLOFs in recent decades. The results show that the breaching probabilities (P ) of 142 PDMDLs range from 0.037 to 0.345, and they can be further categorized as 43 lakes with very high breach probabilities (P ≥ 0.24), 47 lakes with high breach probabilities (0.18 ≤ P < 0.24), 24 lakes with mid-level breach probabilities (0.12 ≤ P < 0.18), 24 lakes with low breach probabilities (0.06 ≤ P < 0.12), and four lakes with very low breach probabilities (p < 0.06).

Extracellular enzymes catalyze rate-limiting steps in soil organic matter decomposition, and their activities (EEAs) play a key role in determining soil respiration (SR). Both EEAs and SR are highly sensitive to temperature, but their responses to climate warming remain poorly understood. Here, we present a meta-analysis on the response of soil cellulase and ligninase activities and SR to warming, synthesizing data from 56 studies. We found that warming significantly enhanced ligninase activity by 21.4% but had no effect on cellulase activity. Increases in ligninase activity were positively correlated with changes in SR, while no such relationship was found for cellulase. The warming response of ligninase activity was more closely related to the responses of SR than a wide range of environmental and experimental methodological factors. Furthermore, warming effects on ligninase activity increased with experiment duration. These results suggest that soil microorganisms sustain long-term increases in SR with warming by gradually increasing the degradation of the recalcitrant carbon pool.

ABSTRACT. Glacier area changes on the Tibetan Plateau were studied in different drainage basins based on Landsat satellite images from three epochs: 263 in the mid-1970s, 150 in 1999-2002 and 148 in 2013/ 14. Three mosaics (M1976, M2001 and M2013) with minimal cloud and snow cover were constructed, and the uncertainty due to each epoch having a finite span was accounted for. Glacier outlines (TPG1976, TPG2001 and TPG2013) were digitized manually with guidance from the SRTM DEM v4.1 and Google Earth imagery. To achieve complete multi-temporal coverage in a reasonable time, only debris-free ice was delineated. Area mapping uncertainty was evaluated at three study sites, Mount Qomolangma (Everest), Mount Naimona'Nyi, Mount Geladandong, where the largest differences between present and earlier measurements were within ∼±4%. Area differences with previous inventories ranged from −19.6% (TPG1976 minus the first Chinese Glacier Inventory) to −3.6% and −1.1% (TPG2013 and TPG2001, respectively minus the second Chinese Glacier Inventory), while the difference TPG2001 minus the GAMDAM Glacier Inventory was +10.4%. Glacier area on the plateau decreased from 44 366 ± 2827 km 2 (1.7% of the study area) in the 1970s to 42 210 ± 1621 km 2 in 2001 and 41 137 ± 1616 km 2 in 2013. Shrinkage was faster in external drainage basins of the southeast than in the interior basins of the northwest, from a maximum of −0.43% a −1 (−1.60% a −1 during 1994-2013) in the Mekong catchment down to a minimum of −0.12% a −1 in the Tarim interior drainage.

No abstract