John A. Dearing

Shadow spaces for social learning: a relational understanding of adaptive capacity to climate change within organisations

Recent UK government policy on climate change, and wider policy movement within the United Nations Framework Convention on Climate Change, emphasise the building of adaptive capacity. But what are the institutional constraints that shape capacity to build adaptive organisations? The authors synthesise theory from social learning and institutional aspects of multilevel environmental governance to help unpack the patterns of individual and collective action within organisations that can enhance or restrict organisational adaptive capacity in the face of abrupt climate change. Theoretical synthesis is grounded by empirical work with a local dairy farmers group and two supporting public sector bodies that are both local actors in their own rights and which also shape the operating environment for other local actors (the Environment Agency and the Welsh Assembly and Assembly-sponsored public bodies). Providing space within and between local organisations for individuals to develop private as well as officially sanctioned social relationships is supported as a pathway to enable social learning. It is also a resource for adaptation that requires little financial investment but does call for a rethinking of the personal skills and working routines that are incentivised within organisations.

Sustainability or Collapse: What Can We Learn from Integrating the History of Humans and the Rest of Nature?

Abstract Understanding the history of how humans have interacted with the rest of nature can help clarify the options for managing our increasingly interconnected global system. Simple, deterministic relationships between environmental stress and social change are inadequate. Extreme drought, for instance, triggered both social collapse and ingenious management of water through irrigation. Human responses to change, in turn, feed into climate and ecological systems, producing a complex web of multidirectional connections in time and space. Integrated records of the co-evolving human-environment system over millennia are needed to provide a basis for a deeper understanding of the present and for forecasting the future. This requires the major task of assembling and integrating regional and global historical, archaeological, and paleoenvironmental records. Humans cannot predict the future. But, if we can adequately understand the past, we can use that understanding to influence our decisions and to create a better, more sustainable and desirable future.

Environmental Applications of Magnetic Measurements

A wide range of examples of the application of magnetic measurements to environmental studies illustrate the advantages of magnetic techniques over conventional methods. Magnetic measurements, in both the field and the laboratory, are particularly useful for reconnaissance work because of their spee and flexibility, Quantification as well as simple diagnosis of the transformation and movement of magnetic minerals within and between the atmosphere, lithosphere, and hydrosphere is practical. Techniques of investigating intrinsic and mineral magnetic properties, in addition to paleomagnetic remanence, are described in subjects as diverse as meteorology, hydrology, sedimentology, geophysics, and ecology.

Flickering gives early warning signals of a critical transition to a eutrophic lake state.

There is a recognized need to anticipate tipping points, or critical transitions, in social–ecological systems. Studies of mathematical and experimental systems have shown that systems may ‘wobble’ before a critical transition. Such early warning signals may be due to the phenomenon of critical slowing down, which causes a system to recover slowly from small impacts, or to a flickering phenomenon, which causes a system to switch back and forth between alternative states in response to relatively large impacts. Such signals for transitions in social–ecological systems have rarely been observed, not the least because high-resolution time series are normally required. Here we combine empirical data from a lake-catchment system with a mathematical model and show that flickering can be detected from sparse data. We show how rising variance coupled to decreasing autocorrelation and skewness started 10–30 years before the transition to eutrophic lake conditions in both the empirical records and the model output, a finding that is consistent with flickering rather than critical slowing down. Our results suggest that if environmental regimes are sufficiently affected by large external impacts that flickering is induced, then early warning signals of transitions in modern social–ecological systems may be stronger, and hence easier to identify, than previously thought.

Coupling temporal and spatial dimensions of global sediment flux through lake and marine sediment records

A major obstacle to our ability to assess future impacts of climate and human activities on the global sediment system is the lack of suitable timescales over which long-term processes and system properties may be observed. A long-term view offers the opportunity to observe pre-impact states, trajectories and the history of responses to forcings. The paper explores the scope of sediment archives in lakes and the continental margin as sources of information to inform about spatio-temporal characteristics of total suspended sediment (TSS) flux across spatial scales ranging from small catchments (<103 km2) to regional–continental basins (103–106 km2), and over timescales varying from decades to millennia. Numerous published studies, representing many geographical regions, provide estimates for sedimentation rates over full- or part-Holocene timescales, based largely on 14C and 210Pb dating. Results from small–medium drainage basins show that, during the Holocene, climate has been largely subordinate to human impact in controlling long-term shifts in sediment loads, though the evidence for short-term climate impacts is also clear. The rise in sediment delivery following major human impact is typically 5–10-fold higher than under undisturbed conditions, but may be higher depending upon the environment and intensity of impact. Sediment-source studies suggest that surface soil rarely dominates the sediment load, and that channel and gully sources often dominate even in small basins. For larger drainage basins, the forcing–response mechanisms are less clear and there is evidence to suggest that values for modern fluxes lie close to long-term averages. A more systematic analysis of the relative magnitude of change in sediment flux in different basin sizes reveals a global trend where relative changes diminish with increasing basin size. The findings suggest that small basins are most responsive to impacts and will show the largest changes in sediment flux. In contrast, large basins with effective storage zones and very slow reaction times lead to far weaker levels of spatio-temporal coupling. One implication is that the most rapid increases in sediment flux to the coast are caused by disturbance in small–medium drainage basins feeding directly to the coast. Overall, lake and marine sediment archives provide a range of useful information, often with high temporal resolution, that is difficult to obtain by other means. Future studies may be able to use these datasets to provide a typological classification of sediment regimes according to different spatio-temporal characteristics of their forcing–response mechanisms.

Determining the sources of atmospheric particles in Shanghai, China, from magnetic and geochemical properties

Abstract The study describes an investigation into the sources of atmospheric particles collected at 11 sites across Shanghai, China, during one week in November 1998. Source ascription is based on mineral magnetic and geochemical properties, and a chemical mass balance (CMB) model. The CMB model shows that the main contributions to total suspended particles (TSPs) are products of coal combustion, with lesser contributions from construction sites, vehicle emissions, windblown soil and steel-making furnaces. The spatial variability of concentration-dependent magnetic parameters and heavy metal concentrations support the findings from the CMB model. In general, the variability of magnetic quotient parameters is lower than for concentration parameters. This suggests that there are relatively constant proportions of low coercivity ‘magnetite’ and high coercivity ‘haematite’ mineral phases in dust samples at all sites, with a dominance of superparamagnetic (SP) and multidomain (MD)+pseudo-single domain (PSD) ‘magnetite’ grains. MD+PSD grains are produced to a large extent by fossil-fuel combustion emissions, particularly from the main iron and steel manufacturing and power generation industrial complex. Linear multiple regression analyses show that some non-destructive and rapid magnetic measurements may be used to estimate the concentrations of common heavy metals in TSPs.

Looking forward through the past : identification of 50 priority research questions in palaeoecology

Summary 1. Priority question exercises are becoming an increasingly common tool to frame future agendas in conservation and ecological science. They are an effective way to identify research foci that advance the field and that also have high policy and conservation relevance. 2. To date there has been no coherent synthesis of key questions and priority research areas for palaeoecology, which combines biological, geochemical and molecular techniques in order to reconstruct past ecological and environmental systems on timescales from decades to millions of years. 3. We adapted a well-established methodology to identify 50 priority research questions in palaeoecology. Using a set of criteria designed to identify realistic and achievable research goals, we selected questions from a pool submitted by the international palaeoecology research community and relevant policy practitioners. This article is protected by copyright. All rights reserved. Accepted Article 4. The integration of online participation, both before and during the workshop, increased international engagement in question selection. 5. The questions selected are structured around six themes: human–environment interactions in the Anthropocene; biodiversity, conservation, and novel ecosystems; biodiversity over long timescales; ecosystem processes and biogeochemical cycling; comparing, combining and synthesizing information from multiple records; and new developments in palaeoecology. 6. Future opportunities in palaeoecology are related to improved incorporation of uncertainty into reconstructions, an enhanced understanding of ecological and evolutionary dynamics and processes, and the continued application of long-term data for better-informed landscape management. 7. Synthesis Palaeoecology is a vibrant and thriving discipline and these 50 priority questions highlight its potential for addressing both pure (e.g. ecological and evolutionary, methodological) and applied (e.g. environmental and conservation) issues related to ecological science and global change.

The Holocene vegetation history of Lake Erhai, Yunnan province southwestern China: the role of climate and human forcings

A pollen diagram from a 6.62 m sediment sequence in Lake Erhai in northwest Yunnan, China was obtained to examine the roles of climate change and human impact on the development of the Erhai lake-catchment system since 12950 cal. yr BP. The record extends back into the Younger Dryas, where the dominance of Betula and deciduous Quercus points to a relatively cold and wet winter climate. After 11 750 cal. yr BP, a warming climate coupled with enhanced summer monsoon precipitation results in the expansion of Tsuga and evergreen broadleaved trees (Cyclobalanopsis, Lithocarpus and Castanopsis). An increase in evergreen oaks and dry-tolerant species after 10 320 cal. yr BP suggests a greater seasonality in rainfall, reflecting a southward shift in the winter front across the region. This trend of increasing temperatures and seasonality is seen to continue through into the mid-Holocene and the onset of the Holocene optimum. A marked decline in arboreal taxa coupled with increased levels of grass (Poaceae) and other disturbance taxa provides the first evidence for human impact in the catchment at c. 6370 cal. yr BP. This early phase of forest clearance leads to the collapse of the natural altitudinal vegetation gradient that existed in the catchment from the Lateglacial. The subsequent expansion of secondary pine forest suggests that these early clearances were part of a sustained period of shifting agriculture. Archaeological and historical records for the region point to a gradual increase in immigration into the region throughout the late Holocene. The increased pressure on the catchment is reflected in the pollen record by a series of clearance phases, which increase in intensity after 2140 cal. yr BP, linked presumably to intensification of agriculture and early urbanization. This trend continues through the last millennium, before a sharp increase in arboreal pollen at the top of the core reflects a phase of reforestation that took place in the catchment over the last 25 years.

Complex Land Systems: the Need for Long Time Perspectives to Assess their Future

The growing awareness about the need to anticipate the future of land systems focuses on how well we understand the interactions between society and environmental processes within a complexity framework. A major barrier to understanding is insufficient attention given to long (multidecadal) temporal perspectives on complex system behavior that can provide insights through both analog and evolutionary approaches. Analogs are useful in generating typologies of generic system behavior, whereas evolutionary assessments provide insight into site-specific system properties. Four dimensions of these properties: (1) trends and trajectories, (2) frequencies, thresholds and alternate steady states, (3) slow and fast processes, and (4) legacies and contingencies, are discussed. Compilations and analyses of past information and data from instruments and observations, palaeoenvironmental archives, and human and environmental history are now the subject of major international effort. The embedding of empirical information over multidecadal timescales in attempts to define and model sustainable and adaptive management of land systems is now not only possible, but also necessary.

Detecting atmospheric pollution in surface soils using magnetic measurements: a reappraisal using an England and Wales database.

Industrial activity such as burning of fossil fuels produces magnetically enhanced particulates. These particulates consist of coarse-grained multidomain and stable single domain magnetic minerals. Two threshold values of low field magnetic susceptibility (chi(LF)) and frequency dependent susceptibility percentage (chi(FD)%) discriminate ferrimagnetic minerals of these sizes and can act as a tracer of magnetic pollution. Application of the thresholds to a magnetic topsoil data set (n=5656 across England and Wales) revealed 637 samples potentially dominated by pollution particulates. The magnetic parameters of these samples display a negative correlation with distance to urban areas and positive correlations with metals associated with anthropogenic activity (Cu, Pb, and Zn). Results of experimentation with threshold values and modelling of magnetic anomalies suggest that regional factors such as geology and potential for pedogenic secondary magnetic enhancement should be considered when setting threshold values.