Land grabbing as a driver of environmental change

A worldwide increase in large-scale land acquisitions over the past decade has been described as a global land rush for access to natural resources. ‘Land grabbing’ is a dynamic of land-use change that can enable especially rapid environmental transformations across vast spatial scales. New scholarship is beginning to address these land deals in terms of their implications for social and political systems, but exploitative land uses also leave legacies of change in physical landscapes. Historical precedents from around the world, including various examples of frontier expansion, reflect the kinds of environmental responses that modern land grabbing could induce. Insights into land grabbing as a mechanism of abrupt, large-scale transitions in human–environmental systems is a research opportunity and a pressing grand challenge for Earth-surface science

Threshold effects of hazard mitigation in coastal human–environmental systems

Despite improved scientific insight into physical and social dynamics related to natural disasters, the financial cost of extreme events continues to rise. This paradox is particularly evident along developed coastlines, where future hazards are projected to intensify with consequences of climate change, and where the presence of valuable infrastructure exacerbates risk. By design, coastal hazard mitigation buffers human activities against the variability of natural phenomena such as storms. But hazard mitigation also sets up feedbacks between human and natural dynamics. This paper explores developed coastlines as exemplary coupled human–environmental systems in which hazard mitigation is the key coupling mechanism. Results from a simplified numerical model of an agent-managed seawall illustrate the nonlinear effects that economic and physical thresholds can impart into coastal human–environmental system dynamics. The scale of mitigation action affects the time frame over which human activities and natural hazards interact. By accelerating environmental changes observable in some settings over human timescales of years to decades, climate change may temporarily strengthen the coupling between human and environmental dynamics. However, climate change could ultimately result in weaker coupling at those human timescales as mitigation actions increasingly engage global-scale systems

Viatical and Life Settlement Securitization: Risks and Proposed Regulation

A new industry grew out of the AIDS crisis of the 1980s: the secondary trade in life insurance policies. Victims of HIV and AIDS faced certain death-half within the first year after diagnosis, and eighty-five percent within three years. Meanwhile, AIDS rendered its victims both physically debilitated and socially untouchable, often cutting them off from employment and employer provided health insurance. Treatment, though largely ineffective, cost the average patient up to $8o,ooo. Those infected-at first, predominantly gay men-were often abandoned by their families, and government programs provided little support

Dynamic allometry in coastal overwash morphology

Allometry refers to a physical principle in which geometric (and/or metabolic) characteristics of an object or organism are correlated to its size. Allometric scaling relationships typically manifest as power laws. In geomorphic contexts, scaling relationships are a quantitative signature of organization, structure, or regularity in a landscape, even if the mechanistic processes responsible for creating such a pattern are unclear. Despite the ubiquity and variety of scaling relationships in physical landscapes, the emergence and development of these relationships tend to be difficult to observe - either because the spatial and/or temporal scales over which they evolve are so great or because the conditions that drive them are so dangerous (e.g. an extreme hazard event). Here, we use a physical experiment to examine dynamic allometry in overwash morphology along a model coastal barrier. We document the emergence of a canonical scaling law for length versus area in overwash deposits (washover). Comparing the experimental features, formed during a single forcing event, to 5 decades of change in real washover morphology from the Ria Formosa barrier system, in southern Portugal, we find differences between patterns of morphometric change at the event scale versus longer timescales. Our results may help inform and test process-based coastal morphodynamic models, which typically use statistical distributions and scaling laws to underpin empirical or semi-empirical parameters at fundamental levels of model architecture. More broadly, this work dovetails with theory for landscape evolution more commonly associated with fluvial and alluvial terrain, offering new evidence from a coastal setting that a landscape may reflect characteristics associated with an equilibrium or steady-state condition even when features within that landscape do not.Funding Agency NERC Natural Environment Research Council NE/N015665/2 Leverhulme Trust RPG-2018-282info:eu-repo/semantics/publishedVersio

A hidden scale dependency in conserving working woodlands

Because plans for large-scale landscape preservation in the US do not rely exclusively on lands held in trust, conservation programs have a vested interest in forest stewardship by private landowners. Selective harvests for commercial sale are often highlighted as a financial incentive for owners of non-industrial "family forests" to sustainably maintain the working character of their acreage rather than subdivide it or convert it for development. However, the business costs inherent in even a small-scale commercial timber harvest typically mean that forest parcels smaller than approximately 80 acres are too small to support a financial return. Statistics for private forest ownership in the U.S. suggest this minimum scale makes commercial harvest incentives effectively inaccessible to more than 90% of forest owners. Rural landscape conservation and commercial timber harvests depend on the same economies of scale to be viable. Designs for regional-scale forest conservation need to account for non-industrial but nonetheless commercial economies of scale that set an inherent limit on financial incentives intended to foster stewardship activity among family-forest landowner

Pushing the pace of tree species migration

Plants and animals have responded to past climate changes by migrating with habitable environments, sometimes shifting the boundaries of their geographic ranges by tens of kilometers per year or more. Species migrating in response to present climate conditions, however, must contend with landscapes fragmented by anthropogenic disturbance. We consider this problem in the context of wind-dispersed tree species. Mechanisms of long-distance seed dispersal make these species capable of rapid migration rates. Models of species-front migration suggest that even tree species with the capacity for long-distance dispersal will be unable to keep pace with future spatial changes in temperature gradients, exclusive of habitat fragmentation effects. Here we present a numerical model that captures the salient dynamics of migration by long-distance dispersal for a generic tree species. We then use the model to explore the possible effects of assisted colonization within a fragmented landscape under a simulated tree-planting scheme. Our results suggest that an assisted-colonization program could accelerate species-front migration rates enough to match the speed of climate change, but such a program would involve an environmental-sustainability intervention at a massive scale

An evolving research agenda for human–coastal systems

Within the broad discourses of environmental change, sustainability science, and anthropogenic Earth-surface systems, a focused body of work involves the coupled economic and physical dynamics of developed shorelines. Rapid rates of change in coastal environments, from wetlands and deltas to inlets and dune systems, help researchers recognize, observe, and investigate coupling in natural (non-human) morphodynamics and biomorphodynamics. This same intrinsic quality of fast-paced change also makes developed coastal zones exemplars of observable coupling between physical processes and human activities. In many coastal communities, beach erosion is a natural hazard with economic costs that coastal management counters through a variety of mitigation strategies, including beach replenishment, groynes, revetments, and seawalls. As cycles of erosion and mitigation iterate, coastline change and economically driven interventions become mutually linked. Emergent dynamics of two-way economic–physical coupling is a recent research discovery. Having established a strong theoretical basis, research into coupled human–coastal systems has passed its early proof-of-concept phase. This paper frames three major challenges that need resolving in order to advance theoretical and empirical treatments of human–coastal systems: (1) codifying salient individual and social behaviors of decision-making in ways that capture societal actions across a range of scales (thus engaging economics, social science, and policy disciplines); (2) quantifying anthropogenic effects on alongshore and cross-shore sediment pathways and long-term landscape evolution in coastal zones through time, including direct measurement of cumulative changes to sediment cells resulting from coastal development and management practices (e.g., construction of buildings and artificial dunes, bulldozer removal of overwash after major storms); and (3) reciprocal knowledge and data exchange between researchers in coastal morphodynamics and practitioners of coastal management. Future research into human–coastal systems can benefit from decades of interdisciplinary work on the complex dynamics of common-pool resources, from computational efficiency and new techniques in numerical modeling, and from the growing catalog of high-resolution geospatial data for natural and developed coastlines around the world

emergent behavior in a coupled economic and coastline model for beach nourishment

Developed coastal areas often exhibit a strong systemic coupling between shoreline dynamics and economic dynamics. Beach nourishment , a common erosion-control practice, involves mechanically depositing sediment from outside the local littoral system onto an actively eroding shoreline to alter shoreline morphology. Natural sediment-transport processes quickly rework the newly engineered beach, causing further changes to the shoreline that in turn affect subsequent beach-nourishment decisions. To the limited extent that this landscape/economic coupling has been considered, evidence suggests that towns tend to employ spatially myopic economic strategies under which individual towns make isolated decisions that do not account for their neighbors. What happens when an optimization strategy that explicitly ignores spatial interactions is incorporated into a physical model that is spatially dynamic? The long-term attractor that develops for the coupled system (the state and behavior to which the system evolves over time) is unclear. We link an economic model, in which town-manager agents choose economically optimal beach-nourishment intervals according to past observations of their immediate shoreline, to a simplified coastal-dynamics model that includes alongshore sediment transport and background erosion (e.g. from sea-level rise). Simulations suggest that feedbacks between these human and natural coastal processes can generate emergent behaviors. When alongshore sediment transport and spatially myopic nourishment decisions are coupled, increases in the rate of sea-level rise can destabilize economically optimal nourishment practices into a regime characterized by the emergence of chaotic shoreline evolution

Indications of a positive feedback between coastal development and beach nourishment

Beach nourishment, a method for mitigating coastal storm damage or chronic erosion by deliberately replacing sand on an eroded beach, has been the leading form of coastal protection in the United States for four decades. However, investment in hazard protection can have the unintended consequence of encouraging development in places especially vulnerable to damage. In a comprehensive, parcel-scale analysis of all shorefront single-family homes in the state of Florida, we find that houses in nourishing zones are significantly larger and more numerous than in non-nourishing zones. The predominance of larger homes in nourishing zones suggests a positive feedback between nourishment and development that is compounding coastal risk in zones already characterized by high vulnerability