Progress in Physical Geography Earth and Environment

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.

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.

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.

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.

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

Wetlands are poorly documented features of many landscapes, and there is often little understanding of the geomorphological controls on their origin, development and characteristics. This paper addresses the apparent paradox of wetlands in drylands, focusing particularly on the geomorphology and sedimentology of wetlands in southern Africa. Drylands are characterized by high (but variable) levels of aridity, reflecting low ratios between precipitation and potential evapotranspiration, so wetlands can only exist where there are locally positive surface water balances for all or part of the year. Most moderate to large wetlands in drylands are thus maintained by river inflows that combine with other factors that serve to impede drainage or reduce infiltration, including faulting, rock outcrops, swelling soils, and ponding by tributary or aeolian sediments. Together with variations in sediment supply, vegetation communities, and levels of animal activity, this promotes a diverse range of wetlands that span a continuum from permanently inundated, to seasonally inundated, to ephemerally inundated. In detail, every wetland has a unique range of geomorphological and sedimentological characteristics but, at a general level, the dryland setting can be shown to impart some distinctive features. By comparison with humid region (tropical and temperate) wetlands, we propose that many wetlands in drylands are characterized by: 1) more frequent and/or longer periods of desiccation; 2) channels that commonly decrease in size and even disappear downstream; 3) higher levels of chemical sedimentation; 4) more frequent fires that reduce the potential for thick organic accumulations and promote aeolian activity; and 5) longer timescales of development that may extend far back into the Pleistocene. Additional studies of wetlands in different drylands may reveal other distinctive characteristics. Correct identification of the factors giving rise to wetlands, and improved understanding of the geomorphological and sedimentological processes governing their development, is vital for the design of sustainable management guidelines for these diverse yet fragile habitats.

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 http://ppg.sagepub.com/cgi/content/abstract/25/2/159. 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.

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.

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 ¹⁴C 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 ¹⁴C 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 ¹⁴C y) than equatorial waters (δR = c. 0 ¹⁴C 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.

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.

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).

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.

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.

Tephra (or volcanic ash) studies, once confined largely to volcanic lands, have become increasingly practised in countries far removed from areas of active or recent volcanism – and Australia is no exception. At the International Union for Quaternary Research (INQUA) conference in Cairns in July/August 2007, Sarah E. Coulter (née Davies), now a postdoctoral ice-core tephrochronologist at Queen’s University Belfast, reportedthe first occurrence of an exotic tephra in Australia in a core from Lynch’s Crater, Atherton Tableland, Queensland (Figure 1). The distal tephra, manifest as a tiny concentration of glass shards, was probably derived from a Papua New Guinean eruption around 75,000–80,000 years ago (S.E. Davies et al., 2007). Its value lies in providing a precise chronostratigraphic marker that potentially allows correlation of other long palaeoenvironmental sequences over wide distances. Davies’ study is but one of a revolutionary development in tephrochronology now focused on detecting diminutive, distal tephras that are invisible in the field and referred to as cryptotephras. From the Greek word kryptein, meaning ‘to hide’ (Hunt, 1999a; Hunt and Hill, 2001; Lowe and Hunt, 2001), cryptotephras typically comprise fine-ashsized (< ~100 μm) glass shards sparsely preserved and ‘hidden’ in peats or in lake, marine or aeolian sediments, or in ice cores (Figure 2). The cryptotephra theme is continued in section III, but beforehand nomenclature associated with the term ‘tephra’, which can be confusing and which sometimes is used incorrectly, is outlined.

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

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.

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.

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.

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

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.

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

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.

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.

Metadata only Soil conservation policies are suggested at national, regional and local levels, including adoption and modification of several Australian, European and North American policies. The Australian Landcare system and programmes of the US Natural Resources Conservation Service (NRCS) are particularly informative. Several European initiatives are promising models, including the strategies of the Danish Land Development Service (Hedeselskabet) and the Icelandic Soil Conservation Service (Landsgraedsla Rikisins). The Erosienormeringsprojekt of South Limburg (The Netherlands) is a coordinated and integrated soil conservation project and seems a particularly useful model for future soil conservation in northern Europe. Several best management practices for soil conservation are identified. These include the promotion of soil conservation by a properly funded and relatively well known soil conservation service and full mapping, monitoring and costing of erosion risk by national soil survey organizations. A participatory approach to soil conservation should be adopted, involving farmers and interested members of the public, and there should be a 'cost share' partnership between government and farmers in funding conservation work on farms. Rational land-use policies need to be developed, such as the promotion of 'set-aside' on erodible soils, grass strips on arable slopes and buffer strips in riparian zones. Education programmes are necessary to actively inform the public on the importance of soil as a resource. These schemes should particularly encourage 'land literacy' among participants. It is imperative that the broader societal benefits of effective soil conservation are recognized, such as its potential contribution to habitat creation, biodiversity and carbon sequestration.