Progress in Physical Geography Earth and Environment

Published by SAGE

Print ISSN: 0309-1333


Figure 2 Climate sensitivity estimates obtained using modern climate data as a constraint, divided into three groups: inference of climate sensitivity directly from data; ensemble studies in which climate sensitivity is varied; and ensemble studies in which physics process parameters are varied. Wigley et al. (2005) base their estimates on three different volcanic eruptions (Table 1). The narrower ranges of Forest et al . (2002, 2006) include additional specifi cations for the values of the ensemble input parameters. Confi dence limits, or other defi nitions of the estimate, are given. The vertical bands indicate the IPCC 2007 (2-4.5°C) and NAS (1.5-4.5°C) ranges (see text) 
Table 2 Estimates of climate sensitivity that use palaeoclimate data (pre-1850) as a constraint
Figure 3 Climate sensitivity estimates obtained using palaeoclimate data as a constraint, divided into three groups: inference of climate sensitivity directly from palaeodata; ensemble studies in which physics process parameters are varied; and results from combining estimates from different eras. Hoffert and Covey base their estimates on two eras: the LGM (solid line) and Mid-Cretaceous (dashed line) 
Figure 4 Climate sensitivity as a function of tropical sea surface temperature change between the pre-industrial and the LGM for three model ensembles: the MIROC3.2 model with PMIP LGM boundary conditions (Annan, private communication); the CLIMBER-2 model with PMIP LGM boundary conditions; and CLIMBER- 2 with additional dust and vegetation forcings (Schneider von Deimling, private communication). For comparison, fi ve PMIP 2 coupled ocean-atmosphere GCMs are shown (Crucifi x, 2006; this paper). The MIROC3.2 ensemble uses a simpler version of the model than PMIP 2 (see text). The vertical lines indicate the 1 σ limits of reconstructed tropical SST change at the LGM from Ballantyne et al. (2005) 
Figure 5 Annual mean sea surface temperature changes between the pre-industrial and the LGM, simulated by four coupled ocean-atmosphere GCMs from PMIP 2 (Braconnot et al. , 2007): CCSM, HadCM3M2, IPSL-CM4-V1-MR and MIROC3.2 
Using the past to constrain the future: How the palaeorecord can improve estimates of global warming
  • Article
  • Full-text available

April 2012


430 Reads



Climate sensitivity is defined as the change in global mean equilibrium temperature after a doubling of atmospheric CO2 concentration and provides a simple measure of global warming. An early estimate of climate sensitivity, 1.5-4.5{\deg}C, has changed little subsequently, including the latest assessment by the Intergovernmental Panel on Climate Change. The persistence of such large uncertainties in this simple measure casts doubt on our understanding of the mechanisms of climate change and our ability to predict the response of the climate system to future perturbations. This has motivated continued attempts to constrain the range with climate data, alone or in conjunction with models. The majority of studies use data from the instrumental period (post-1850) but recent work has made use of information about the large climate changes experienced in the geological past. In this review, we first outline approaches that estimate climate sensitivity using instrumental climate observations and then summarise attempts to use the record of climate change on geological timescales. We examine the limitations of these studies and suggest ways in which the power of the palaeoclimate record could be better used to reduce uncertainties in our predictions of climate sensitivity.

Lunar Resources: A Review

April 2015


5,165 Reads

There is growing interest in the possibility that the resource base of the Solar System might in future be used to supplement the economic resources of our own planet. As the Earth's closest celestial neighbour, the Moon is sure to feature prominently in these developments. In this paper I review what is currently known about economically exploitable resources on the Moon, while also stressing the need for continued lunar exploration. I find that, although it is difficult to identify any single lunar resource that will be sufficiently valuable to drive a lunar resource extraction industry on its own (notwithstanding claims sometimes made for the 3He isotope, which I find to be exaggerated), the Moon nevertheless does possess abundant raw materials that are of potential economic interest. These are relevant to a hierarchy of future applications, beginning with the use of lunar materials to facilitate human activities on the Moon itself, and progressing to the use of lunar resources to underpin a future industrial capability within the Earth-Moon system. In this way, gradually increasing access to lunar resources may help 'bootstrap' a space-based economy from which the world economy, and possibly also the world's environment, will ultimately benefit.

Ecological epidemiology: The role of landscape structure in the transmission risk of the fox tapeworm Echinococcus multilocularis (Leukart 1863) (Cestoda: Cyclophyllidea: Taeniidae)

March 2005


42 Reads

The larval form of the fox tapeworm Echinococcus multilocularis causes a fatal liver infection in humans and has high prevalence in western China. The tapeworm lifecycle involves small mammal populations and canids, such as foxes and dogs. Human contact with infected canids may lead to the transmission of the worm to humans, causing the disease human alveolar echinococcosis. This paper introduces the tapeworm and reviews the current understanding of its transmission ecology in relation to each component of its lifecycle. Recent research indicates that landscape plays an important role in creating the necessary habitat conditions for natural transmission. Defining the landscape involves the use of satellite imagery, land cover classification and spatial analysis. The link between disease, remote sensing and landscape ecology is an expanding research area and potentially an important one in relation to Echinococcus multilocularis and alveolar echinococcosis.

Land cover change in Europe between 1950 to 2000 determined employing aerial photography

April 2010


1,263 Reads






BIOPRESS (‘Linking Pan-European Land Cover Change to Pressures on Biodiversity’), a European Commission funded ‘Global Monitoring for Environment and Security’ project, produced land cover change information (1950—2000) for Europe from aerial photographs and tested the suitability of this for monitoring habitats and biodiversity. The methods and results related to the land cover change work are summarized. Changes in land cover were established through 73 window and 59 transect samples distributed across Europe. Although the sample size was too small and biased to fully represent the spatial variability observed in Europe, the work highlighted the importance of method consistency, the choice of nomenclature and spatial scale. The results suggest different processes are taking place in different parts of Europe: the Boreal and Alpine regions are dominated by forest management; abandonment and intensification are mainly encountered in the Mediterranean; urbanization and drainage are more characteristic of the Continental and Atlantic regions.

Aeolian-fluvial interactions in dryland environments: Examples, concepts and Australia case study

December 2003


147 Reads

Over the past 10 to 15 years there has been a rising interest in interactions between aeolian and fluvial processes from geomorphologists and sedimentologists. This reflects recognition of the limitations of a reductionist perspective examining single process systems in understanding landform and landscape development. This paper focuses on the rise of aeolian-fluvial interaction research in dryland environments. We first explore the background to the contemporary situation then review existing research on aeolian-fluvial interactions at global/regional and local scales. From this review it is suggested that landscape sensitivity, or the effectiveness of links between the process systems, spatial environmental transitions and temporal environmental change are the three main driving forces determining the geomorpho-logical significance of aeolian-fluvial interactions. The importance of the first two of these driving forces is explored in more detail using Australia as a case study. We conclude by highlighting some future possible research directions in this field. Yes Yes

Table 1 : Past, present and planned orbital SAR missions.
Figure 2: Interference of iso-phase lines of two SAR sensors separated by a spatial baseline B. 
Forest mapping and monitoring with interferometric Synthetic Aperture Radar (InSAR)

April 2001


1,240 Reads

This is the author's final draft of the paper published as Progress in Physical Geography, 2001, 25 (2), pp. 159-177. The final version is available from Doi: 10.1177/030913330102500201 A synthetic aperture radar (SAR) is an active sensor transmitting pulses of polarized electromagnetic waves and receiving the backscattered radiation. SAR sensors at different wavelengths and with different polarimetric capabilities are being used in remote sensing of the earth. The value of an analysis of backscattered energy alone is limited due to ambiguities in the possible ecological factor configurations causing the signal. From two SAR images taken from similar viewing positions with a short time-lag, interference between the two waves can be observed. By subtracting the two phases of the signals, it is feasible to eliminate the random contribution of the scatterers to the phase. The interferometric correlation and the interferometric phase contain additional information on the three-dimensional structure of the scattering elements in the imaged area. A brief review of SAR sensors is given, followed by an outline of the physical foundations of SAR interferometry and the practical data-processing steps involved. An overview of applications of InSAR to forest mapping and monitoring is given, covering tree-bole volume and biomass, forest types and land cover, fire scars, forest thermal state and forest canopy height.

Approaches to modelling Land erodibility by wind

October 2009


292 Reads

Land susceptibility to wind erosion is governed by complex multiscale interactions between soil erodibility and non-erodible roughness elements populating the land surface. Numerous wind erosion modelling systems have been developed to quantify soil loss and dust emissions at the field, regional and global scales. All of these models require some component that defines the susceptibility of the land surface to erosion, ie, land erodibility. The approaches taken to characterizing land erodibility have advanced through time, following developments in empirical and process-based research into erosion mechanics, and the growing availability of moderate to high-resolution spatial data that can be used as model inputs. Most importantly, the performance of individual models is highly dependent on the means by which soil erodibility and surface roughness effects are represented in their land erodibility characterizations. This paper presents a systematic review of a selection of wind erosion models developed over the last 50 years. The review evaluates how land erodibility has been modelled at different spatial and temporal scales, and in doing this the paper identifies concepts behind parameterizations of land erodibility, trends in model development, and recent progress in the representation of soil, vegetation and land management effects on the susceptibility of landscapes to wind erosion. The paper provides a synthesis of the capabilities of the models in assessing dynamic patterns of land erodibility change, and concludes by identifying key areas that require research attention to enhance our capacity to achieve this task.

Fig 3: Outline of the modern North Atlantic showing ΔR values (in circles, from 
Figure list: 
Methodological approaches to determining the marine radiocarbon reservoir effect

December 2005


897 Reads

The marine radiocarbon reservoir effect is an offset in 14C age between contemporaneous organisms from the terrestrial environment and organisms that derive their carbon from the marine environment. Quantification of this effect is of crucial importance for correct calibration of the <sup>14</sup>C ages of marine-influenced samples to the calendrical timescale. This is fundamental to the construction of archaeological and palaeoenvironmental chronologies when such samples are employed in <sup>14</sup>C analysis. Quantitative measurements of temporal variations in regional marine reservoir ages also have the potential to be used as a measure of process changes within Earth surface systems, due to their link with climatic and oceanic changes. The various approaches to quantification of the marine radiocarbon reservoir effect are assessed, focusing particularly on the North Atlantic Ocean. Currently, the global average marine reservoir age of surface waters, R(t), is c. 400 radiocarbon years; however, regional values deviate from this as a function of climate and oceanic circulation systems. These local deviations from R(t) are expressed as +R values. Hence, polar waters exhibit greater reservoir ages (δR = c. +400 to +800 <sup>14</sup>C y) than equatorial waters (δR = c. 0 <sup>14</sup>C y). Observed temporal variations in δR appear to reflect climatic and oceanographic changes. We assess three approaches to quantification of marine reservoir effects using known age samples (from museum collections), tephra isochrones (present onshore/offshore) and paired marine/terrestrial samples (from the same context in, for example, archaeological sites). The strengths and limitations of these approaches are evaluated using examples from the North Atlantic region. It is proposed that, with a suitable protocol, accelerator mass spectrometry (AMS) measurements on paired, short-lived, single entity marine and terrestrial samples from archaeological deposits is the most promising approach to constraining changes over at least the last 5 ky BP.

The Use of Reservoir Sediments as Environmental Archives of Catchment Inputs and Atmospheric Pollution

September 2005


107 Reads

Published following peer-review in Progress in Physical Geography. Published by and copyright Sage Publications. Full-text of this article is not available in this e-prints service. Lakes and reservoirs act as sinks for both catchment and atmospherically derived particulates and so their sediments can provide valuable information on temporal changes in these inputs. While the use of lake sediments as environmental archives is well established, reservoir sediments have less frequently been used as temporal records. Yet, for investigating pollution histories, reservoirs are ostensibly of greater interest: they are generally located close to urban and industrial sources of pollution and accumulate sediment rapidly and over similar time periods to major emissions of pollutants. The lack of interest in reservoir sediments stems from the perception that fluctuating water levels are likely to result in significant sediment disturbance. This perception is sustained, perhaps mistakenly, by a lack of research into reservoir sedimentary systems. There is, therefore, a need to review the available published research on reservoir sedimentation processes and patterns, the relatively few studies that have used reservoir sediments and relevant studies from the lake-sediment literature, and thus critically evaluate the potential and problems of using reservoir sediments as temporal records of pollution. Current understanding of the processes of sedimentation and resulting distributions are reviewed. Some significant differences between sedimentation in lakes and reservoirs are highlighted and the implications for sampling and interpretation of sedimentary records discussed. It is suggested that, at present, a valuable resource is being underutilized and it is demonstrated that, where sediment deposition patterns are taken into account, reservoir sedimentary records can provide important data for reconstructing past atmospheric and catchment pollutant inputs.

Arid geomorphology: Recent progrees from an Earth System Science perspective

February 2008


59 Reads

These progress reports provide an opportunity for refl ection on the direction of academic inquiry and discourse in physical geography, and hopefully serve as an antidote to the everyday whirlwind of events and short-term deadlines that we are all caught up in. Since the last report (Tooth, 2007), arid geomorphological research output has remained strong, and it is only possible to cite a small selection of published work in the space available here. As ever, research approaches, topics, and themes are diverse, as exemplifi ed by special issues arising from the joint British Geomorphological Research Group/ British Sedimentological Research Group conference (London, 2005) entitled ‘Drylands: Linking Landscape Processes to Sedimentary Environments’, which demonstrate the overlap between those studies concerned primarily with present-day arid processform relationships and those focusing on how these relationships are represented in Quaternary sedimentary successions and the sedimentary rock record (Bullard et al., 2007; Nash et al., 2007).

Arid geomorphology: Emerging research themes and new frontiers

June 2009


125 Reads

Research conducted at the interfaces between traditionally disparate academic disciplines can provide fresh perspectives that catalyse novel research approaches and themes. With particular reference to publications from the last few years, this report focuses on a selection of emerging research themes that highlight the growing links between arid geomorphology and other disciplines, including ecology and soil science, sedimentology and petroleum geology, and planetary science. Three themes are addressed: (1) the role of fire in arid geomorphological systems, characterized by investigations that tend to focus on surface processes and landforms at relatively small spatial scales (plot to short channel reach) and short timescales (hours to years); (2) arid fluvial sedimentary systems, characterized by investigations that commonly focus on processes, landforms and sedimentary products at larger spatial scales (channel reach to basin) and longer timescales (years to millions of years); and (3) arid geomorphology on Mars, commonly characterized by process-landform investigations at very large spatial scales (entire physiographic regions to full planetary contexts) and yet longer timescales (millions to billions of years). For each theme, research gaps are identified, which provides an indication of where the research frontier currently lies. In particular, geomorphological research on Mars and other planetary bodies represents a new physical and intellectual frontier that offers great potential for further interplay with Earth landscape studies in arid and other climatic regions. While there are concerns about the present health and direction of geomorphology and physical geography, this rich diversity of themes provides evidence for vigorous and focused research in arid geomorphology.

Table 1 Reported hydrological effects of peatland drainage
Table 2 Processes discussed by Robinson (1980) that could account for changes in flow regime (increased annual runoff and flood peak) at Coalburn
Artificial drainage of peatlands: Hydrological and hydrochemical process and wetland restoration

March 2003


2,651 Reads

Peatlands have been subject to artificial drainage for centuries. This drainage has been in response to agricultural demand, forestry, horticultural and energy properties of peat and alleviation of flood risk. However, the are several environmental problems associated with drainage of peatlands. This paper describes the nature of these problems and examines the evidence for changes in hydrological and hydrochemical processes associated with these changes. Traditional black-box water balance approaches demonstrate little about wetland dynamics and therefore the science of catchment response to peat drainage is poorly understood. It is crucial that a more process-based approach be adopted within peatland ecosystems. The environmental problems associated with peat drainage have led, in part, to a recent reversal in attitudes to peatlands and we have seen a move towards wetland restoration. However, a detailed understanding of hydrological, hydrochemical and ecological process-interactions will be fundamental if we are to adequately restore degraded peatlands, preserve those that are still intact and understand the impacts of such management actions at the catchment scale.

A conceptual model for integrating physical geography research and coastal wetland management, with an Australian example

September 2010


55 Reads

We have developed a conceptual model to assist integration between physical geographical sciences, institutional frameworks and management in the context of coastal wetlands. Wetlands are key interconnected systems that will respond early to climate change and especially to associated sea-level changes. A major constraint on management of wetlands is the lack of congruence between the ecosystems and the institutional frameworks that govern their management: connectivity in coastal systems is overlain by institutional fragmentation. We introduce a model that facilitates integration of physical geographical (biophysical) information into the legislative, planning, policy and management process. It consists of interconnected parallel subprojects in science and in planning with strong cross-links with stakeholders at all levels, founded on long-term and trusting relationships. We also show progress that has been made in applying the model, with an Australian example. It is concluded that the approach has potential to move towards the goal of sustainable management but that it urgently needs to evolve, so as to meet the challenges of climate and associated changes. Yes Yes

Biodiversity and extinction: Losing the common and the widespread

April 2007


1,666 Reads

Introduction extract: Species-level conservation activities tend to be focused on those species that are highly threatened with global or regional extinction in the near future. This is broadly logical, if one of the principal goals is to retain as great a proportion of the composition of original species assemblages as possible, within the severe constraints of available conservation resources. In the main, those species which have a high likelihood of rapidly becoming regionally or globally extinct also have small total population sizes and/or restricted geographic ranges within the appropriate region or worldwide (Gaston, 1994; 2003). That is, the importance of each individual organism to the persistence of the species is on average high, and/or there is limited spatial spreading of risk, increasing the vulnerability of the species to quite localized threats.

Recent research on the nature, origin and climatic relations of blocky and stratified slope deposits

December 2002


628 Reads

A selection of subaerial slope processes is discussed together with the morphological and sedimentological traces that are left by the processes. Emphasis is on mass transfers related to (coarse) blocky slopes and to scree accumulations, either on steep or on gentle slopes. New developments in the interpretation of more or less clearly stratified slope deposits are discussed in the light of the findings of research focusing on present-day process-form (process-material) relationships. The question of the climatic (and, more specifically, the periglacial) significance of the different processes and their morpho-sedimentary expression is a returning theme in this paper. It is concluded that many deposits are formed by azonal processes, although their activity (in terms of magnitude-frequency combinations) is often relatively high under periglacial conditions. Some of the deposits point to (cold-climate) extreme events. This especially is the case for frost-coated clast flows, aeolian transport of large platy clasts, and to a lesser extent debris flows.

Figure 1 A flow diagram showing the process of construction of a DEM through the intermediary of a contour map
Figure 3 The SK40 2020 km tile of the Ordnance Survey 50 m resolution DEM of Britain. (A) Standard grey scale view; (B) histogram with the diagnostic cyclic peaks indicating over-representation of the contour linesand; (C) slope map showing steep slopes at both the contour positions (very steep slopes – white lines) and integer rounding in low relief areas (moderate slopes – grey lines) Source: © Crown Copyright/Database right 2005. An Ordnance Survey/EDINA supplied service.  
Fisher PE, Tate NJ. Causes and consequences of error in digital elevation models. Progress in Physical Geography

August 2006


1,729 Reads

All digital data contain error and many are uncertain. Digital models of elevation surfaces consist of files containing large numbers of measurements representing the height of the surface of the earth, and therefore a proportion of those measurements are very likely to be subject to some level of error and uncertainty. The collection and handling of such data and their associated uncertainties has been a subject of considerable research, which has focused largely upon the description of the effects of interpolation and resolution uncertainties, as well as modelling the occurrence of errors. However, digital models of elevation derived from new technologies employing active methods of laser and radar ranging are becoming more widespread, and past research will need to be re-evaluated in the near future to accommodate such new data products. In this paper we review the source and nature of errors in digital models of elevation, and in the derivatives of such models. We examine the correction of errors and assessment of fitness for use, and finally we identify some priorities for future research.

Three Gorges Project: Efforts and challenges for the environment

December 2010


914 Reads

The Three Gorges Project has been subject to intense debates regarding its benefits and costs. The environmental impacts of this huge project have been an important focus of these debates since the project planning stage. After the operation of the Three Gorges Dam at full capacity at the end of 2008, new environmental and ecological issues are emerging. This paper gives a brief description of the Three Gorges Project and its environmental impact assessment process, as well as major efforts to control environmental problems brought about by the project. From the long and complicated evaluation process, it is clear that there are large uncertainties and competing opinions regarding the benefits and costs, especially the ecological and environmental ones, of the project even after great research effort. Emphasis here is given to the environmental challenges including: (1) water quality control; (2) water and sediment regulation; (3) biodiversity conservation in the riparian and aquatic ecosystems; (4) environmentally friendly dam operation and regional sustainable development. Opportunities often grow out of the challenges. The Three Gorges Project provides opportunities for grand-scale experiments on the environmental, ecological, and socio-economic impacts of large dams. Local, national, and international concerted efforts and concrete actions should be directed to the mitigation and control of the negative impacts as well as securing the positive contributions of the project across scales Yes Yes

Figure 2 Neuse River Estuary water-quality model Source: reprinted from Paerl and Lung, 1988, with permission from Elsevier.  
A review and classification of the existing models of cyanobacteria

February 2006


977 Reads

Bloom-forming and toxin-producing cyanobacteria remain a persistent nuisance across the world. Modelling of cyanobacteria in freshwaters is an important tool for understanding their population dynamics and predicting bloom occurrence in lakes and rivers. In this paper existing key models of cyanobacteria are reviewed, evaluated and classified. Two major groups emerge: deterministic mathematical and artificial neural network models. Mathematical models can be further subcategorized into those models concerned with impounded water bodies and those concerned with rivers. Most existing models focus on a single aspect such as the growth of transport mechanisms, but there are a few models which couple both.

Did humid-temperate rivers in the Old and New Worlds respond differently to clearance of riparian vegetation and removal of woody debris?

March 2005


165 Reads

Clearance of riparian vegetation and removal of woody debris are perhaps the most pervasive of all forms of human disturbance to river courses. Geomorphic consequences of these impacts have varied markedly from river system to river system, a result of variations in catchment setting, climate, geology, sediment supply and evolutionary history. In this paper, geomorphic responses of rivers to rapid, systematic clearance of riparian vegetation in New World (colonial) societies are contrasted with changes associated with gradual, piecemeal, yet progressive clearance of riparian forests in northern Europe (the Old World). It is postulated that the dramatic nature of river metamorphosis experienced in landscapes such as southeastern Australia records the breaching of fundamental geomorphic thresholds in a different manner to that experienced in Old World landscapes Yes Yes

Mesoscale and local climates in New Zealand

October 1999


37 Reads

New Zealand is a country of marked local and regional environmental variability. The complexity of the terrain and significant relief of this island nation surrounded by extensive areas of ocean produce rapid changes of climate over relatively short distances. This article provides a selective review of recent research into the mesoscale and local climates of this interestingly varied environment. Research completed on energy budgets of the varying surface types provides the starting point for an assessment of thermal effects on the atmospheric boundary layer and airflow. The dynamic effects of surface topography are also seen to have a major impact on regional and local airflow patterns, as well as on mesoscale variations of convection and precipitation. It is clear that the interaction of mid-latitude synoptic weather systems with the mountains of New Zealand produces distinct patterns of wind and rainfall that have a major impact on the physical and human environment of the country. The fohn nor'wester and southerly changes are significant local meteorological phenomena, while mesoscale climate processes are increasingly recognized as important for agricultural activities, the management of hydrological systems and in dealing with environmental problems such as air pollution.

Table 1 Some biogeographical characteristics of Mediterranean-type ecosystems
Table 3 A summary of nature conservation policy and legislation in the Mediterranean
Table 4 Globally threatened groups of species and protected areas in the Mediterranean Basin
Table 5 The state of floristic information in the Mediterranean countries
Mediterranean ecosystems: Problems and tools for conservation

April 2006


1,022 Reads

Mediterranean ecosystems rival tropical ecosystems in terms of plant biodiversity. The Mediterranean Basin (MB) itself hosts 25 000 plant species, half of which are endemic. This rich biodiversity and the complex biogeographical and political issues make conservation a difficult task in the region. Species, habitat, ecosystem and landscape approaches have been used to identify conservation targets at various scales: ie, European, national, regional and local. Conservation decisions require adequate information at the species, community and habitat level. Nevertheless and despite recent improvements/efforts, this information is still incomplete, fragmented and varies from one country to another. This paper reviews the biogeographic data, the problems arising from current conservation efforts and methods for the conservation assessment and prioritization using GIS. GIS has an important role to play for managing spatial and attribute information on the ecosystems of the MB and to facilitate interactions with existing databases. Where limited information is available it can be used for prediction when directly or indirectly linked to externally built models. As well as being a predictive tool today GIS incorporate spatial techniques which can improve the level of information such as fuzzy logic, geostatistics, or provide insight about landscape changes such as 3D visualization. Where there are limited resources it can assist with identifying sites of conservation priority or the resolution of environmental conflicts (scenario building). Although not a panacea, GIS is an invaluable tool for improving the understanding of Mediterranean ecosystems and their dynamics and for practical management in a region that is under increasing pressure from human impact.

Ecosystem process models at multiple scales for mapping tropical forest productivity

June 2004


28 Reads

Quantifying mass and energy exchanges within tropical forests is essential for understanding their role in the global carbon budget and how they will respond to perturbations in climate. This study reviews ecosystem process models designed to predict the growth and productivity of temperate and tropical forest ecosystems. Temperate forest models were included because of the minimal number of tropical forest models. The review provides a multiscale assessment enabling potential users to select a model suited to the scale and type of information they require in tropical forests. Process models are reviewed in relation to their input and output parameters, minimum spatial and temporal units of operation, maximum spatial extent and time period of application for each organization level of modelling. Organizational levels included leaf-tree, plot-stand, regional and ecosystem levels, with model complexity decreasing as the time-step and spatial extent of model operation increases. All ecosystem models are simplified versions of reality and are typically aspatial. Remotely sensed data sets and derived products may be used to initialize, drive and validate ecosystem process models. At the simplest level, remotely sensed data are used to delimit location, extent and changes over time of vegetation communities. At a more advanced level, remotely sensed data products have been used to estimate key structural and biophysical properties associated with ecosystem processes in tropical and temperate forests. Combining ecological models and image data enables the development of carbon accounting systems that will contribute to understanding greenhouse gas budgets at biome and global scales.

Figure 1 A classification of the principal landforms of glacial erosion and the spatial scales at which these landforms occur Source: modified from Bennett and Glasser (1996)
Glacial erosional landforms: Origins and significance for palaeoglaciology

March 2004


6,916 Reads

Glacial inversion modelling of continental-scale palaeo-ice sheets is now recognized as an important tool in palaeoglaciology. Existing palaeoglaciological reconstructions of the dimensions, geometry and dynamics of former ice sheets are based mainly on glacial depositional, as opposed to glacial erosional, landforms. Part of the reason for this is a lack of detailed understanding of the origin and significance of glacial erosional landforms. Here we review recent developments in our understanding of the processes and landforms of glacial erosion and consider their value in palaeoglaciology. Glacial erosion involves the removal and transport of bedrock and/or sediment by glacial quarrying, glacial abrasion and glacial meltwater. These processes combine to create a suite of landforms that are frequently observed in areas formerly occupied by ice sheets and glaciers, and which can be used in palaeoglaciological reconstructions. For example, all landforms of glacial erosion provide evidence for the release of subglacial meltwater and the existence of warm-based ice. Landforms of glacial quarrying such as roches moutonnées, rock basins and zones of areal scouring are created when cavities form between an ice sheet and its bed and therefore are indicative of low effective basal pressures (0.1–1 MPa) and high sliding velocities that are necessary for ice–bed separation. Fluctuations in basal water pressure also play an important role in the formation of glacially quarried landforms. Landforms of glacial abrasion include streamlined bedrock features (‘whalebacks’), some ‘p-forms’, striae, grooves, micro-crag and tails, bedrock gouges and cracks. Abrasion can be achieved by bodies of subglacial sediment sliding over bedrock or by individual clasts contained within ice. Although abrasion models depend critically on whether clasts are treated as dependent or independent of subglacial water pressure, it appears that abrasion is favoured in situations where effective basal pressures are greater than 1 MPa and where there are low sliding velocities. Consequently, landforms dominated by glacial abrasion are created when there is no ice–bed separation. Landforms of glacial meltwater erosion include both subglacial and ice-marginal meltwater channels. Investigations of the relationship between glacial meltwater channels and other aspects of the subglacial drainage system, such as areas of ice–bed contact, areas of ice–bed separation and precipitate-filled depressions, enable inferences to be made concerning former subglacial water pressure-drainage relationships, effective pressures and glacier velocities. Meltwater palaeovelocity and palaeodischarge can also be calculated from measurements of channel shape, channel width and the size of material transported within former glacial meltwater channels. We surmize that glacial erosional landforms offer insight into former glaciological conditions at both the landform- and landscape-scale within palaeoglaciology. Exposureage dating techniques, including cosmogenic isotope dating of bedrock surfaces, will be important in increasing our understanding of the age and chronological significance of landforms of glacial erosion. We conclude that landforms of glacial erosion are of great value in ice mass reconstruction and speculate that these landforms will achieve greater recognition within palaeoglaciology in line with improvements in exposure-age dating techniques.

The philosophy, nature and practice of forensic sediment analysis

February 2007


548 Reads

The rapidly expanding field of forensic geoscience derives its roots from nineteenth- and early twentieth-century scientists who both influence and are influenced by literature and fictional writing. Forensic geoscience borrows much, but not all, of its precepts from geological and geomorphological analytical techniques. Fundamental differences exist between forensic geoscience and its sister disciplines, fundamental enough to make the unwary geoscientist succumb to philosophical and practical pitfalls which will not only endanger the outline of their report, but may well indeed provide false-negative or false-positive results leading to contrary or inaccurate conclusions. In the law, such outcomes have devastating and untenable consequences. Forensic geoscience requires techniques of exclusion rather than inclusion and an acknowledgement that analytical techniques may be diagnostic only in very specific situations. Whether analysis of the ubiquitous or the exotic component is chosen, acknowledgement of the need for samples to be representative is required. The presentation of false-positive results or the lack of identification of sample ‘mixing’ is prerequisite to the application of statistical tests which must be applied in the most careful manner. The realization of the limitations of the technique requires, wherever possible, conjunctive analysis by other truly independent techniques. While personal opinion derives from experience, there is no place for assumption. Research papers in forensic geoscience are not submitted to be speculative or challenging as may be the case in many fields of geomorphology and geology. There is no place for conjecture in forensic geoscience.

Glaciohydraulic supercooling

February 2008


112 Reads

In this progress report we review recent work which has investigated the process of glaciohydraulic supercooling and its significance for a range of glaciological and geological phenomena. Since our last report (Knight and Cook, 2008), glaciohydraulic supercooling has been identified in new locations and under hitherto unrecognized conditions, both for modern and formerly glaciated environments. Recent work has examined the record of supercooling preserved in the landform and sediment record, within tunnel valleys and in sequences of melt-out till. We suggest that supercooling may also have important implications for glacier dynamics because of the role it may play in controlling the geometry of subglacial overdeepenings, which in turn acts as a control on the dynamics of tidewater glaciers. Despite these numerous recent scientific advances, there remains a need to critically evaluate the importance of supercooling for the various aspects of sediment entrainment and flux, glacial geomorphology and ice dynamics with which it has become associated. We illustrate how collaboration with researchers in other branches of cryospheric science, such as sea-ice scientists, might shed new light on the significance of supercooling within these various aspects of glacier science.

Global warming

July 1998


24 Reads

Global warming-like deforestation, the ozone hole and the loss of species- has become one of the late 20the century icons of global environmental damage. The threat, is not the reality, of such a global climate change has motivated governments. businesses and environmental organisations, to take serious action ot try and achieve serious control of the future climate. This culminated last December in Kyoto in the agreement for legally-binding climate protocol. In this series of three lectures I will provide a perspective on the phenomenon of global warming that accepts the scientific basis for our concern, but one that also recognises the dynamic interaction between climate and society that has always exited The future will be no different. The challenge of global warning is not to pretend it is not happening (as with some pressure groups), nor to pretend it threatens global civilisation (as with other pressure groups), and it is not even a challenge to try and stop it from happening-we are too far down the road for this. Rather, the real challenge is to use the opportunity that global climate change persents us with to re-order our energy, commercial and government institutions so that our children and grandchildren can live and survive a world that is both adaptable to change and sustainable.

Knowledge-theoretic models in hydrology

March 2010


27 Reads

The rate of progress in quantitative modelling since the 1950s has been such that application of sophisticated computer models to a wide range of geoscientific problems is now routine. It is generally held that by making such models more physically (physics) based, their explanatory power and predictive reliability are enhanced. This formulation, a model-theoretic approach, assumes accurate knowledge of the properties, states and relationships between all of the objects that are known to matter within the system of interest but, simultaneously, an incomplete understanding of the totality that this knowledge creates. In hydrological modelling, this translates into a severe dependence upon the data models that are needed to make a hydrological model work. The opposite extreme is a model-data approach in which measurements become the basis of generic relationships. Even in the most heavily data-derived cases (eg, neural network forecasting of river flows) these data models can be shown implicitly to have a theoretical content. Thus, both model-theoretic and model-data approaches sit within a general class of modelling, best labelled as 'data-theoretic'. Here, we illustrate this point and advocate an approach that is knowledge-theoretic rather than data-theoretic, to capture the much richer sources of knowledge available to the modeller. These sources include third-party reports, personal recollections and diaries, old photographs and press articles, opinions, etc, which are, by convention, either excluded from analysis, or simply added into descriptions of model results at the point of dissemination and consultation of model findings. We conclude by noting that this approach to hydrological modelling fits into current thinking that the process by which publics engage with knowledge must be moved upstream. Here, the production of scientific knowledge comes to include not just scientists and specialists, but also those people for whom model predictions make a material difference.

Progress in satellite remote sensing of ice sheets

October 2009


206 Reads

Understanding the changing mass balance and surface dynamics of the Earth’s major ice sheets in Greenland and Antarctica is of fundamental importance for accurate predictions of future sea-level rise. In this review, the remote sensing data sources available to ice-sheet studies are considered and the range of information that can be gained from remote sensing is examined. The review demonstrates that the integration of a range of remote sensing data sets can provide information on ice-sheet dynamics and volume changes, melt patterns and formation and drainage of supra- and subglacial lakes. Such data are highly complementary to field investigations by providing a regional-scale, synoptic perspective. The review concludes that emerging remote sensing techniques such as SAR interferometry, feature tracking, scatterometry, altimetry and gravimetry provide vital information without which an understanding of ice sheets would be far less advanced. It also concludes that there remain several key challenges for remote sensing, in particular relating to the observation of rapid dynamical changes that are characteristic of contemporary ice-sheet response to continued climatic warming. RCUK Fellowship

Steffen K, Abdalati W and Stroeve J (1993) Climate sensitivity studies of the Greenland ice sheet using satellite AVHRR, SMMR SSM/I and in situ data. Meteorology and Atmospheric Physics 51(3–4): 239–258. DOI:10.1007/bf01030497

April 2021


12 Reads

Physical geographer Konrad “Koni” Steffen, lost 8 August 2020 in a crevasse on the Greenland ice sheet, was a pioneer in satellite remote sensing and field observations of the Greenland ice sheet. This Classics Revisited piece honors the memory of Koni Steffen and examines the impact of a work which laid the foundation for numerous studies that made the Greenland ice sheet and the man global icons of climate change.

A classic examination of fluvial processes and forest patterns: Victor Ernest Shelford's (1954) 'Some Lower Mississippi Valley Flood Plain Communities: Their Age and Elevation'. Ecology 35(2): 126-142.1

December 2014


27 Reads

The study of the interaction between fluvial processes and forest community patterns owes elements of its origins to the research of Shelford (1954) on the Mississippi River valley. Shelford (1954) is a classic for many reasons; three highlighted here are its role of establishing a methodology for applying historical resources for long-term research studies, its influence on developing conceptual models of forest succession relative to multiple controlling factors, and its recognition of the rapid and extensive impact of human activities on altering natural land-cover patterns and the important role of analog forests for management and conservation. References to Shelford (1954) within the literature have increased every year since its publication and I believe its presence among varied disciplines will continue.

Edward N Lorenzs 1963 paper, "Deterministic nonperiodic flow", in Journal of the Atmospheric Sciences, Vol 20, pages 130-141: Its history and relevance to physical geography

February 2016


575 Reads

Lorenz (1963) provided the foundation of chaos theory and inspired a fundamental reappraisal of systems’ nonlinearity in many disciplines, including physical geography. I will provide a brief overview of chaos in nonlinear systems as documented in Lorenz (1963), including the major tenants of chaos theory, followed by a discussion of the effects of chaos theory within meteorology and climate sciences, geomorphology, and ecology and biogeography. In general, Lorenz (1963) provided the intellectual framework for reconsidering the predictability of many physical systems.

Figure 1. Joseph Grinnell in 1904. Public domain photo. 
Figure 2. Joseph Grinnell in the field in the Sierra Nevada Mountains of California, 1915. Public domain photo. 
Figure 3. Gopher " esker " on Niwot Ridge, Colorado, with 50 mm lens cap for scale. Photo by Butler. 
Revisiting an early classic on gopher bioturbation and geomorphology: Joseph Grinnell (1923) The burrowing rodents of California as agents in soil formation Journal of Mammalogy 4(3): 137–149

July 2017


427 Reads

Joseph Grinnell’s 1923 paper on the burrowing effects of pocket gophers is a classic in the literature of zoogeomorphology and ecology. It established the significance of gophers as agents of bioturbation, and provided quantitative data on the amount of sediment moved annually by them. Its citation in other classic bioturbation papers, and the citation of those papers to the present day, indicates its continuing significance as a classic paper in the field.

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