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This progress report is the first of three overviews of important fields of study within contemporary glaciology, illustrated with reference to exemplar research contributions and highlighting key developments in each field since 2005, the date of the last review of ‘Glaciology’ in this journal. The topics covered in this paper are: (1) the mass balance of glaciers and ice sheets and their contributions to global sea level change; and (2) atmospheric melt-induced influences on the dynamics of the Greenland Ice Sheet. The paper aims to provide an overview of key developments over the last six years from each topic, with discussion of the continuing debates and unresolved issues which constitute the foci for ongoing and future research. [ABSTRACT FROM AUTHOR]

The protection and the sustainable management of soil resources in Africa are of paramount importance, particularly in the context of the uncertain impact of climate change and the increasing pressures of human activities. From the perspective of a policy-maker interested in topics such as food security and land degradation in Africa, this situation requires up-to-date and relevant soil information at regional and continental scales. To provide timely and reliable information on soils at synoptic scales, moderate and coarse spatial resolution satellite data offer many possibilities. The paper reviews how a range of multispectral, thermal infrared, passive microwave and active microwave spaceborne sensors can be used in the delineation of soil units, as well as in the assessment of some of their key properties and threats to soil functions from pressures such as water and wind erosion, landslides and salinization. The paper shows that remotely sensed data can be used for mapping soils in Africa but often need to be combined with ancillary data and field observations in order to be effective. Remote sensing is shown to be a key component of the emerging discipline of digital soil mapping. [ABSTRACT FROM PUBLISHER]

Dew has broad relevance to physical geography and many human activities. This paper reviews the observation and simulation of rural and urban dew, and the implications of dew as a climatic phenomenon. There is no universal protocol for measuring dew (i.e., condensation on cooled surfaces), its component fluxes (dewfall and distillation) or guttation, which is 'dewdrops' exuded from leaves. The many methods that exist to measure dew and surface moisture range from simple visual assessment, to electronic wetness sensors, lysimetry and remote sensing. Most studies of dew are rural; urban dew data are rare and studies seldom address dew in patchy landscapes, e.g., a forest clearing. Hardware dew models are rare. Numerous numerical models exist to simulate or forecast dew on rural crops but few address dew for surfaces other than leaves, e.g., a cocoa pod or road. There is a general consensus in the literature that dew is reduced or absent in cities because of the urban heat island effect and reduced vapour supply.However,little data exist to test this. Given the broad relevance of dew to many topics, future studies of dew in complex landscapes, including urban areas, would prove valuable. [ABSTRACT FROM AUTHOR]

Retention and sequestration of soil organic matter is extremely important for the maintenance of soil structure, agricultural productivity and carbon sequestration. Research in soil organic matter has advanced on many fronts in the last half century. During this time understanding of the factors governing plant litter decomposition has increased considerably resulting in the formulation of process and organism-based models. Remote sensing has been shown to be useful for quickly monitoring stocks of soil organic carbon in the topsoil although much remains to be done to establish its efficacy. Fluxes of soil organic matter in the changing climatic scenarios have been studied though outcomes remain debatable. In this paper an attempt is made to present these various aspects of soil organic matter cohesively. The focus is mainly on litter decomposition, models and monitoring methods, role of soil aggregates and erosion, impact of climate change on long-term dynamics of soil organic matter and impending research themes needing further attention. [ABSTRACT FROM AUTHOR]

Dynamic global vegetation models (DGVMs) offer explicit representations of the land surface through time and have been used to research large-scale hydrological responses to climate change. These applications are discussed and comparisons of model inputs and formulations are made among and between DGVMs and global hydrological models. It is shown that the configuration of process representations and data inputs are what makes a given DGVM unique within the family of vegetation models. The variety of available climatic forcing datasets introduces uncertainty into simulations of hydrological variables. It is proposed that satellite-derived data, validated thoroughly, could be used to improve the quality of model evaluations and augment ground-based observations, particularly where spatial and temporal gaps are present. This would aid the reduction of model uncertainties and thus potentially enhance our understanding of global hydrological change. [ABSTRACT FROM AUTHOR]

The Arctic is thought to be an area where we can expect to see the first and strongest signs of global-scale climate variability and change. We have already begun to see a reduction in: (1) the aerial extent of sea ice at about 3% per decade and (2) ice thickness at about 40%. At the current rate of reduction we can expect a seasonally ice-free Arctic by midway through this century given the current changes in thermodynamic processes controlling sea-ice freeze-up and decay. Many of the factors governing the thermodynamic processes of sea ice are strongly tied to the presence and geophysical state of snow on sea ice, yet snow on sea ice remains poorly studied. In this review, we provide a summary of the current state of knowledge pertaining to the geophysical, thermodynamic and dielectric properties of snow on sea ice. We first give a detailed description of snow thermophysical properties such as thermal conductivity, diffusivity and specific heat and how snow geophysical/electrical properties and the seasonal surface energy balance affect them. We also review the different microwave emission and scattering mechanisms associated with snow-covered first-year sea ice. Finally, we discuss the annual evolution of the Arctic system through snow thermodynamic (heat/mass transfer, metamorphism) and aeolian processes, with linkages to microwave remote sensing that have yet to be defined from an annual perspective in the Arctic. [ABSTRACT FROM AUTHOR]

Mountain glaciers are key indicators of climate change, although the climatic variables involved differ regionally and temporally. Nevertheless, there has been substantial glacier retreat since the Little Ice Age and this has accelerated over the last two to three decades. Documenting these changes is hampered by the paucity of observational data. This review outlines the measurements that are available, new techniques that incorporate remotely sensed data, and major findings around the world. The focus is on changes in glacier area, rather than estimates of mass balance and volume changes that address the role of glacier melt in global sea-level rise. The glacier observations needed for global climate monitoring are also outlined. [ABSTRACT FROM AUTHOR]

Climatologists have speculated that a spatially coherent pattern of high-latitude temperature trends could be an early indicator of climatic change. The sensitivity of sea ice to the temperature of the overlying air suggests the possibility that trends in Arctic ice conditions may be useful proxy indicators of general climatic changes. Aspects of the north-polar ice pack which have been identified as key parameters to be monitored include ice extent, concentration, type, thickness and motion dynamics. In spite of the considerable interannual, regional and seasonal variations exhibited by these data, there may be some evidence of an emerging trend towards decreasing ice extent and concentration. Collecting data in such a remote and harsh environment to support these analyses is only possible through satellite remote sensing. Remote sensing in the microwave portion of the electromagnetic spectrum is particularly relevant for polar applications because microwaves are capable of penetrating the atmosphere under virtually all conditions and are not dependent on the sun as a source of illumination. In particular, analyses of passive microwave imagery can provide us with daily information on sea-ice extent, type, concentration, dynamics and melt onset. A historical record of Arctic imagery from orbiting passive microwave sensors starting from 1973 provides us with an excellent data source for climate change studies. The development of analysis tools to support large area monitoring is integral to advancing global change research. The critical need is to create techniques which highlight the space-time relationships in the data rather than simply displaying voluminous quantities of data. In particular, hypertemporal image analysis techniques are required to help find anticipated trends and to discover unexpected or anomalous temporal relationships. Direct hypertemporal classification, principal components analysis and spatial time-series analysis are identified as three primary techniques for enhancing change in temporal image sequences. There is still a need for the development of new tools for spatial- temporal modelling. [ABSTRACT FROM PUBLISHER]