Wind transports particles by creep, saltation and suspension, of which saltation dominates and is responsible for aeolian landforms. Transported particles generally must go around objects, so that the connectivity defined by the spatial distribution of objects on the surface controls sediment transport. Four spatial and temporal scales of sediment transport are defined. At gap to patch scales, vegetation typically defines the structural connectivity. Vegetation remains important at landscape to basin scales but geomorphic features also contribute to defining transport corridors, or structural connectivity, at the coarsest scale. Patterns of aeolian transport through time are essentially constrained by structural connectivity at multiple, embedded scales. Functional connectivity is not well developed in the aeolian realm and, because particles do not travel more than one or two saltation hops during a single event, functional connectivity is only a relevant concept at the finest spatial scales. Aeolian transport must be approached from the multiple spatial (gap to basin) and temporal (single event to longer periods) scales that define structural and functional connectivity.

Periglacial regions and processes are particularly affected by contemporary climate change. These changes modify sediment connectivity and flux significantly. Connectivity is dynamic, evolving in response to the sediment transport processes it itself induces; and connection and disconnection have to be viewed as relative and multi-variate concepts. For most of the time, a landscape is functionally disconnected; sediment does not move. When it does move, at more connected locations it is more likely to move further downstream. However, because such sediment flux (i.e., functional connectivity) may cause landscape changes that in turn change connection, this static structural representations of connectivity also need to be considered as non-stationary. We illustrate these points using examples from the Arolla and Ferpecle-Mont Miné Valleys, located in the Val d’Hérens of Canton Valais, in Switzerland. These examples: (1) illustrate the spatial variability of the functional connectivity; (2) show how structural connectivity interacts with the processes that drive sediment flux; and (3) demonstrate the ways in which sediment flux can lead to evolution of structural connectivity.

Farming has modified the natural dynamic of soil erosion/redistribution in significant parts of landscapes, triggering high rates of soil loss and accelerating sediment connectivity. This chapter provides a review of sediment connectivity in grassland, herbaceous and woody crops from knowledge to management. The first section explores the extension of farmland at a global scale and the process of agricultural land expansion. Regarding herbaceous crops, the second section highlights the importance of cropping intensity (one or two crops per year), water supply (rainfed or irrigated), and crop rotation on the sediment-connectivity magnitude. In the section of woody crops, studies done in vineyards, olive groves and citrus orchards describe the processes of sediment connectivity with and without soil conservation practices (e.g., cover crops). The section of sediment connectivity in grasslands includes examples in alpine hillsides, valley bottom and lakes, emphasizing their role as sediment-trapping features. The last section deals with sediment dis-connectivity in farmland due to soil erosion control practices and governmental programs, with examples from Europe and China.

This chapter reviews how climate change is projected to affect the frequency, severity and/or spatial distribution of tropical cyclones, severe storms that generate tornadoes, and floods; the factors that influence people’s exposure and vulnerability to such events; adaptation options for reducing displacement risks; and, common characteristics of migration and displacement across all categories of extreme weather events. We then focus on specific types of extreme weather and provide more detailed analyses and case studies of migration and displacement events associated with tropical cyclones, tornadoes, and floods.

A number of indices has been proposed to assess hydrological or sediment connectivity. These indices operate at different spatial scales, address different types of connectivity (hillslope-channel vs. longitudinal connectivity), are based on different spatial units (raster cell, landform, channel reach, sub-/catchment) and approaches (geomorphological mapping, digital elevation models, network analysis). Temporal constraints for the application of indices exist as connectivity depends on the magnitude of hydrometeorological forcing, and is subject to changes in landscape properties. Connectivity indices are based on variables and assumptions with respect to space and time. We review existing indices of different characteristics (raster, effective catchment area, networks) together with examples, and distinguish two types of their application: descriptive applications in which indices are used to describe spatial patterns of water and sediment (coupled and decoupled) pathways for a point or period of time; and as predictors of connectivity and its consequences (e.g., sediment transfer, sensitivity to change). Opportunities and challenges for research in connectivity indices are discussed.

The concept of connectivity appeared in several disciplines in the 1950s and 1960s, but did not enter geomorphology until the 1980s. The concept has led to profound insights into the behaviour of systems, and has had significant applications in management. Connectivity may be defined as a structured set of relationships between spatially and/or temporally distinct entities), or as the degree to which a system facilitates (or impedes) the movement of matter and energy through itself. The former definition focuses on the structure of the system, and the latter on the functioning of it. The two definitions give rise to the separate concepts of structural and functional connectivity. A fundamental difference between structural and functional connectivity lies in the fact that, whereas the former can be relatively easily measured, and a variety of tools exists to do so, the latter tends to be inferred from system behaviour, so that measurement is somewhat indirect. Notwithstanding the compelling arguments in favour of studying connectivity, the ability to apply the ideas of connectivity science in any discipline requires a number of challenges to be addressed.

Vegetation cover in drylands tends to be sparse and organised as a mosaic of patches with high biomass interspersed within a bare soil component. Water availability and vegetation are tightly coupled in these environments, where landscape function is determined by hydrologic and sediment connectivity. In this chapter, we analyse and synthesise previous studies describing how understanding, measuring and modifying connectivity can be used to guide the design of management strategies aiming at improving landscape resilience. We describe how drylands are very sensitive to both water and wind erosion, which have the potential to increase connectivity beyond tipping points at which the system transitions abruptly to a degraded state that may be irreversible. We discuss methods for the identification of early warning indicators of transition to degraded states, which could be used as a preventive management tool. We also describe existing strategies and approaches to reduce connectivity at different spatial scales as a way of managing degraded landscapes.

Scholarly understanding of these topics has evolved rapidly over recent decades, yet there is still much we don’t know about the complex ways that climate change interacts with migration decisions. In this final chapter, we discuss a number of emerging issues and future research needs including: gendered dimensions of migration in the context of future climate change, how climate-related migration affects Indigenous populations and cultural heritage, the interplay between climate-related migration and human health, the impacts of climate-related migration on receiving communities, identification of critical thresholds in climate-migration connections, and unforeseeable climate-migration outcomes.

This chapter provides an overview of policymaking that is being done at international, regional, and national levels, highlighting some of the key processes and frameworks relevant to climate-related migration and displacement. We discuss the extent to which these policies respond adequately (or not) to the needs and complexity of the challenge. We also describe a range of actors that have been actively engaged in these policymaking processes and the nature of their influence on these processes. We assess the different levels of actors in descending order of scale, starting with an overview of international policy frameworks and processes and then moving through regional and national level processes and approaches. Although we assess each level separately, they should be viewed as a network or web of interconnected actors and processes that influence one another, even as they evolve.

In this chapter, the history and development of the concept of connectivity in geomorphology is presented. It further provides an overview of connectivity terminology, the underlying concepts and identifies the benefits of connectivity thinking for geomorphological research and applications. We further pursue the question of whether connectivity can be considered as key concept in geomorphology and address general key challenges in using connectivity to understand complex geomorphic systems.