The science of the total environment

Glaciers distinct from the Greenland and Antarctic ice sheets cover an area of approximately 706,000 square kilometres globally1, with an estimated total volume of 170,000 cubic kilometres, or 0.4 metres of potential sea-level-rise equivalent2. Retreating and thinning glaciers are icons of climate change3 and affect regional runoff4 as well as global sea level5,6. In past reports from the Intergovernmental Panel on Climate Change, estimates of changes in glacier mass were based on the multiplication of averaged or interpolated results from available observations of a few hundred glaciers by defined regional glacier areas7–10. For data-scarce regions, these results had to be complemented with estimates based on satellite altimetry and gravimetry11. These past approaches were challenged by the small number and heterogeneous spatiotemporal distribution of in situ measurement series and their often unknown ability to represent their respective mountain ranges, as well as by the spatial limitations of satellite altimetry (for which only point data are available) and gravimetry (with its coarse resolution). Here we use an extrapolation of glaciological and geodetic observations to show that glaciers contributed 27 ± 22 millimetres to global mean sea-level rise from 1961 to 2016. Regional specific-mass-change rates for 2006–2016 range from −0.1 metres to −1.2 metres of water equivalent per year, resulting in a global sea-level contribution of 335 ± 144 gigatonnes, or 0.92 ± 0.39 millimetres, per year. Although statistical uncertainty ranges overlap, our conclusions suggest that glacier mass loss may be larger than previously reported11. The present glacier mass loss is equivalent to the sea-level contribution of the Greenland Ice Sheet12, clearly exceeds the loss from the Antarctic Ice Sheet13, and accounts for 25 to 30 per cent of the total observed sea-level rise14. Present mass-loss rates indicate that glaciers could almost disappear in some mountain ranges in this century, while heavily glacierized regions will continue to contribute to sea-level rise beyond 2100.The largest collection so far of glaciological and geodetic observations suggests that glaciers contributed about 27 millimetres to sea-level rise from 1961 to 2016, at rates of ice loss that could see the disappearance of many glaciers this century.

Global glacier mass changes and their contributions to sea-level rise from 1961 to 2016

: A system is described which: (a) replaces existing sets of diverse terrain indices with a group of statistics for point-characteristics; (b) calculates all of these statistics in a single computer run from a single data set; and (c) utilizes available altitude matrix data The procedures are applicable to Altitude matrix data at any grid mesh From altitudes in each 3 x 3 submatrix, a quadratic surface is fitted and solved for its first and second horizontal and vertical derivatives at the central point This yields the slope gradient, slope aspect, profile convexity, and plan convexity at every point in the original matrix, except for the peripheral rows and columns These 'point' descriptors are presented as: (1) line-printer shaded maps; (2) histograms; (3) scatter plots of each pair; (4) matrix of pair-wise correlations, plus circular regressions on aspect, and several multiple regressions, and (5) summary (moment-based) statistics In general, the five basic descriptors have little relation to each other, except that gradient is usually a quadratic function of altitude A comparison is made with other approaches, such as spectral analysis and fractal modelling The long-distance persistence properties of terrain mean that considerable extra variance at long wavelengths is usually incorporated when the study area is extended Hence the auto correlation function varies with the length of series or size of area Variance of derivatives are also affected, but means, skews, and kurtoses are not

Statistical Characterization of Altitude Matrices by Computer. Report 6. An Integrated System of Terrain Analysis and Slope Mapping.

Himalayan glacier tongues are commonly debris covered and they are an important source of melt water. However, they remain relatively unstudied because of the inaccessibility of the terrain and the difficulties in field work caused by the thick debris mantles. Observations of debris-covered glaciers are therefore scarce and airborne remote sensing may bridge the gap between scarce field observations and coarse resolution space-borne remote sensing. In this study we deploy an Unmanned Aerial Vehicle (UAV) before and after the melt and monsoon season (May and October 2013) over the debris-covered tongue of the Lirung Glacier in Nepal. Based on stereo-imaging and the structure for motion algorithm we derive highly detailed ortho-mosaics and digital elevation models (DEMs), which we geometrically correct using differential GPS observations collected in the field. Based on DEM differencing and manual feature tracking we derive the mass loss and the surface velocity of the glacier at a high spatial accuracy. On average, mass loss is limited and the surface velocity is very small. However, the spatial variability of melt rates is very high, and ice cliffs and supra-glacial ponds show mass losses that can be an order of magnitude higher than the average. We suggest that future research should focus on the interaction between supra-glacial ponds, ice cliffs and englacial hydrology to further understand the dynamics of debris-covered glaciers. Finally, we conclude that UAV deployment has large potential in glaciology and it may revolutionize methods currently applied in studying glacier surface features.

High-Resolution Monitoring of Himalayan Glacier Dynamics Using Unmanned Aerial Vehicles

An evaluation of the effectiveness of low-cost UAVs and structure from motion for geomorphic change detection

. Air pollution is a major environmental concern for many populations
worldwide. Communication efforts so far have been based on a one-way
provision of evidence and information from experts to society, and have
arguably failed in their mission to foster a more aware and engaged society,
or to result in cleaner air. Globally we are facing both an air quality
crisis and a communication emergency. This paper focuses on the communication
of air pollution risk, from the threats it poses (e.g. severe impacts to
human health) to the opportunities it can create (e.g. behavioural or
technological alternatives that lead to cleaner air). It supports the case
for moving away from one-way communication, and identifies five key benefits
of a practical two-way communication between experts and citizens in order to
engender positive change and improve global air quality.

/pdf/give-me-five-reasons-for-two-way-communication-between-4mpmx1cb3q.pdf

Give me five! – reasons for two-way communication between experts and citizens in relation to air pollution risk

Determination of the physical, chemical and biological properties of glacier ice is essential for many aspects of glaciology and glacial geomorphology. In this chapter, we draw principally on examples of the description and sampling of the basal zone of glaciers where the ice is in direct contact with its substrate, and hence is where a great deal of geomorphological work is achieved. Whilst a pre-determined sampling strategy is essential to inform sampling equipment requirements, flexibility in data collection is necessary because of the dynamic nature of glaciers, and variability of ice exposure. Ice description is best achieved through stratigraphic logging, section drawing and photography. Detailed description can include a variety of information about the nature of layering, structures and sediment distribution; the size, shape and roundness of included debris; ice crystallography; and bubble content. It is common practice to categorise descriptively different ice types into cryofacies, so that comparisons can be made between studies. Sample extraction may be required for more detailed analyses of the physical, chemical and microbiological composition of the ice. We outline the use of a number of tools for ice sample extraction, including chainsaws, ice axes, chisels and ice screws.

Sampling and Describing Glacier Ice

<p>Addressing the question of whether Glacial Lake Outburst Floods (GLOFs) are changing in frequency and magnitude in modern times requires historical context, but suffers from incomplete GLOF inventories, especially in remote mountain regions. Here, we exploit high-resolution, multi-temporal satellite and aerial imagery combined with documentary data to identify GLOF events across the glacierized Cordilleras of Peru and Bolivia, using a set of diagnostic geomorphic features. More than 150 GLOFs are characterised and analysed, far exceeding the number of previously reported events. We provide statistics on location, magnitude, timing and characteristics of these events. Further, we describe several cases in detail and document a wide range of process chains associated with GLOFs. Our findings outline implications for regional GLOF hazard identification and assessment and provide solid basis for enhanced understanding GLOF occurrence under changing climate conditions and glacier retreat.</p>

A new GLOF inventory for the Peruvian and Bolivian Andes

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Origin and age of The Hillocks and implications for post‐glacial landscape development in the upper Lake Wakatipu catchment, New Zealand

. We present the first assessment of microbial cell discharge from sediment-laden glacier basal ice. At Svinafellsjokull, a temperate valley glacier in Iceland, approximately 1017 cells a−1 are transferred through basal ice to the proglacial environment, and between 101 and 106 cells g−1 basal ice were cultured from our samples under laboratory conditions. We suggest that the delivery of viable cells and dead microbial matter to proglacial ecosystems could be playing a crucial role in soil formation and primary succession during deglaciation, but further quantification of cell transfer from a range of glacier contexts is required.

/pdf/quantification-of-basal-ice-microbial-cell-delivery-to-the-531u6xkn5b.pdf

Simon J. Cook

Papers

Give me five! – reasons for two-way communication between experts and citizens in relation to air pollution risk

Sampling and Describing Glacier Ice

A new GLOF inventory for the Peruvian and Bolivian Andes

Origin and age of The Hillocks and implications for post‐glacial landscape development in the upper Lake Wakatipu catchment, New Zealand

Quantification of basal ice microbial cell delivery to the glacier margin