Land Degradation, Desertification and Climate Change

Anticipating, assessing and adapting to future change

Mark S. Reed, Lindsay C. Stringer

• Publisher: Routledge
• Year: 2016
• eBook ISBN: 9781135094300
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Ecology

Although much is known about the processes and effects of land degradation and climate change, little is understood about the links between them. Less still is known about how these processes are likely to interact in different social-ecological systems around the world, or how societies might be able to adapt to this twin challenge. This book identifies key vulnerabilities to the combined effects of climate change and land degradation around the world. It identifies triple-win adaptations that can tackle both climate change and land degradation, whilst supporting biodiversity and ecosystem services.

The book discusses methods for monitoring effects of climate change and land degradation, and adaptations to these processes. It argues for better co-operation and knowledge exchange, so that the research, land user and policy communities can work together more effectively to tackle these challenges, harnessing the "wisdom of crowds" to assess vulnerability and adapt to climate change and land degradation, whilst protecting livelihoods and biodiversity.

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INTRODUCTION

Climate change and land degradation are closely interlinked and are most acutely experienced by ecosystems and resource-dependent populations in regions affected by desertification and drought. It is essential to understand and address the dual challenges of climate change and land degradation if we are to meet targets such as the Sustainable Development Goals (SDGs), tackle poverty and address many of the most pressing environmental challenges of the twenty-first century.

Although much is known about the processes and effects of land degradation and climate change, less is understood about the links between these two challenges. Less still is known about how climate change and land degradation processes are currently interacting in different social-ecological systems around the world, or how they might interact under different scenarios in the future. However, there are major challenges associated with anticipating the combined effects of climate change and land degradation processes, given numerous inherent, and often contradictory, feedbacks. Climate change and land degradation processes operate differently in different ecosystems¹, and within the same ecosystems under different forms of land management. This leads to a range of effects on ecosystem processes², which in turn influence the provision of ecosystem services³ to society. This may give rise to a number of potentially important but possibly unforeseen impacts on populations in regions affected by Desertification, Land Degradation and Drought (DLDD)⁴. Moreover, limited understanding of feedbacks among these processes restricts our capacity for anticipatory adaptation. There is an increasingly urgent need for research to elucidate these links, so that land users and policy-makers can respond in timely and effective ways.

In this book we look at how land users, the policy and research communities and other stakeholders can work together to better anticipate, assess and adapt to the combined effects of climate change and land degradation in regions affected by DLDD. We also consider some of the behavioural, governance and policy changes that may be needed to facilitate effective adaptation to future change at national and international scales. We consider all regions affected by DLDD but place special emphasis on drier areas, because these are often considered most vulnerable to DLDD.

Using the United Nations Convention to Combat Desertification (UNCCD) definition which encompasses arid, semi-arid and dry sub-humid parts of the world, drylands occupy around 41 per cent of the Earth’s land area and are home to around a third of the world’s population (MA, 2005). The proportion of drylands thought to be affected by land degradation in the form of desertification depends largely on the definition of dryland, as well as the assessment method used, with estimates of 10 per cent (Lepers et al., 2005), 38 per cent (Mabbutt, 1984), 64 per cent (Dregne, 1983), and 71 per cent (Dregne and Chou, 1992). A key attempt to quantify land degradation was undertaken in the Millennium Ecosystem Assessment, which suggests a figure of 10–20 per cent of drylands are degraded with “medium certainty” (MA, 2005), with degradation severity and extent highest in Africa and Asia⁵.

At the same time as the challenge of land degradation, climate change is leading to global changes in temperature, rainfall, sea level rise, increasing concentrations of carbon dioxide (CO₂) and other greenhouse gases in the atmosphere, and an increase in the incidence and severity of extreme weather events. A possible temperature increase of 1–3°C in drylands, if CO₂ concentrations were to reach 700 p.p.m. by 2050, would increase global potential evapotranspiration by around 75–225 mm per year. Climate models have predicted that up to 50 per cent of the Earth’s surface will be experiencing regular drought by the end of the twenty-first century under a “business as usual” scenario, with drylands in northern Africa, Amazonia, the United States, southern Europe and western Eurasia likely to become drier, while higher latitudes of the northern hemisphere are likely to become wetter (Burke et al., 2006; Seager et al., 2007; D’Odorico et al., 2013). In more temperate locations however, higher temperatures may lengthen growing seasons (Cantagallo et al., 1997; Travasso et al., 1999). Elevated concentrations of atmospheric CO₂ are likely to have a fertilizing effect on plants, boosting primary productivity, and would likely increase the efficiency with which plants use water to create biomass (Le Houérou, 1996; Chun et al., 2013; Keenan et al., 2013; Kaminski et al., 2014). At the same time, these effects are likely to be offset by negative effects of elevated tropospheric ozone and the impacts of changing distributions of weeds, pests and diseases, as well as changes to the composition of vegetation communities. In the chapters that follow, we explore these changes in more depth.

In this book we take an interdisciplinary and integrated approach to climate change and land degradation, considering them as interlinked concepts that have biophysical and human drivers, impacts and responses. Although interactions between climate change and land degradation are likely to give rise to a number of new challenges, there may also be a number of overlaps, as well as scope for synergy, between the behaviours, governance models and policy instruments that may be needed to address these issues. By bringing together scientific and other forms of knowledge from around the world (including local, traditional, indigenous and lay knowledge, which we collectively term “locally held knowledge”), it may be possible to reduce the vulnerability of ecosystems and populations to these threats, in currently affected areas and beyond, and to build overall resilience. We therefore consider how an integrated approach to addressing land degradation and climate change can be developed, in order to harness synergies and multiple benefits, as well as outlining some of the potential ways forward.

1.1 Climate change and land degradation in regions affected by DLDD: key definitions

Before attempting to understand the nature of the interlinkages between climate change and desertification, land degradation and drought, it is important to begin by providing some clarity in the definitions we are using – not least because they are all terms that are used differently by different stakeholders and researchers working within different disciplines.

1.2 Climate change

Climate can be thought of as a statistical description of the weather, taking into account variables including temperature, wind speed and direction, and rainfall, over a long time period. The World Meteorological Organization (WMO) usually considers this long time period to span from more than 30 years up to thousands of millions of years. Often, we think of the climate as being the conditions we experience at the Earth’s surface. However, climate is really a summary of the state of the broader climate system, which includes a range of complex interactions between the atmosphere (the blanket of gases surrounding the Earth), hydrosphere (the water components present on the Earth), the cryosphere (the frozen parts of the planet) and the biosphere (parts of the Earth where life is found). The broader climate system has its own internal dynamics but is also affected by external biophysical phenomena such as volcanic eruptions on Earth, changes to the sun including variation in solar activity and the intensity of light energy, as well as human-induced changes in the composition of the atmosphere. This results in direct or indirect changes in the Earth’s climate through feedbacks that operate on different timescales (IPCC, 2007).

According to the Intergovernmental Panel on Climate Change (IPCC, 2001), the primary international scientific body providing advice to the United Nations on climate-related challenges, climate change refers to a variation in climate that persists over decades or longer, that is statistically significant in terms of its mean state or its variability. Other definitions attempt to attribute climate change either directly or indirectly to human activities such as deforestation and industrialization, which change the balance of gases in the global atmosphere (e.g. UNFCCC, 1992, Article 1). Making links to human activities is very important for political/decision-making reasons, especially if international action is to be taken to address climate change. It presents the issue as more than just a natural occurrence, implicating humans in the problem and legitimating the need for policy action to develop solutions.

1.3 Defining land degradation and desertification

Land degradation is a process that can happen in any climatic zone, not just in drylands. Land degradation in drylands is sometimes referred to as “desertification”. UNCCD (1994) defines desertification as “land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities”. UNCCD (1994) defines land degradation as a

reduction or loss, in arid, semi-arid, and dry sub-humid areas, of the biological or economic productivity and complexity of rain-fed cropland, irrigated cropland, or range, pasture, forest, and woodlands resulting from land uses or from a process or combination of processes, including processes arising from human activities and habitation patterns, such as: (i) soil erosion caused by wind and/or water; (ii) deterioration of the physical, chemical, and biological or economic properties of soil; and (iii) long-term loss of natural vegetation.

This definition of land degradation therefore refers to:

• Decline in biological and/or economic resilience (i.e. the ability of a system to maintain the structure essential to support the basic system functions (such as biological habitat, biomass production, filtering, buffering, storage and transformation of nutrients, water retention) during times of stress or perturbation (Holling, 1986; Ballayan, 2000); or

• Loss of adaptive capacity (the ability – often measured in the time it takes – for a system to regain the structure essential to support basic system functions after stress or perturbation of the land system (Kasperson et al., 1995; IPCC, 2001).

These considerations emphasize the importance of maintaining basic ecosystem processes, functions and services that may or may not include human uses. This approach to defining land degradation conceptualizes land as including all elements of the biosphere at or below the Earth’s surface, incorporating soil, terrain, surface hydrology, groundwater, plants and animals, human settlements and the physical evidence of past and present human activity. As such, any approach to tackling land degradation needs to consider how to mitigawte impacts on underpinning ecosystem processes and prevent critical thresholds in natural capital from being crossed, in addition to mitigating the consequent loss of ecosystem services. For this reason, Reed et al. (2015: 472) argue that mechanisms for tackling land degradation need to be “based on retaining critical levels of natural capital whilst basing livelihoods on a wider range of ecosystem services”.

The role of human activities in causing land degradation is important. For example, reductions in, or losses of, productivity and resilience can stem from soil erosion caused by wind and/or water; a loss of quality or integrity of the physical, chemical and biological or economic properties of soil and a loss or change in natural vegetation. Each of these changes is driven largely by human activities such as land use change, mining and habitation patterns (including urbanization). Erosion can have particularly important economic impacts on agricultural land, where the redistribution of soil within a field, the loss of soil from a field, the breakdown of soil structure, and the decline in organic matter and nutrients, can all result in a reduction of cultivable soil depth and a decline in soil fertility (Morgan, 2005).

Despite the scientific evidence that supports the role of human activities as a key driver of land degradation, some scientists also consider that climatic variation (particularly drought) and longer-term drying out, aridification or ‘desiccation’ (due to climate change) are important contributing factors that underpin land degradation, particularly because desiccation can cause reductions in productivity and vegetation loss. Indeed, because drylands are water-limited environments, it can mean that water degradation (in terms of quality and quantity) can have substantial effects on both ecosystem integrity and human well-being.

Some scientists have suggested that land degradation can only be determined in relation to the goals of the management system at the time of investigation (e.g. Turner and Benjamin, 1993), and in the context of a specific time frame, spatial scale, economy, environment and culture (Warren, 2002). This means that the same biophysical environmental change (e.g. erosion) can create different problems and have different consequences in different contexts. Warren argued that if soil erosion is

of no consequence to production at a larger spatial scale, it does not contribute to degradation in the wider context. If it has no impact on future production, it is not degradation in the longer term. A change in a component of the environment that cannot be accessed with present technology or finance, or is inconsequential to a present way of life, does not, per se, amount to degradation.

(2002: 449)

As such, the extent and severity of land degradation being experienced may vary between land users with different management goals in different places at different times and in different socio-economic, environmen...

Table of contents

• Cover
• Half Title
• Title page
• Copyright Page
• Table of Contens
• List of illustrations
• Acronyms and abbreviations
• Acknowledgements
• Foreword
• 1 Introduction
• 2 Policy context
• 3 Conceptual and methodological frameworks
• 4 Exposure and sensitivity of provisioning ecosystem services
• 5 Exposure and sensitivity of other ecosystem services and feedbacks between climate change and land degradation
• 6 Responses
• 7 Monitoring and evaluating current and future effects of climate change and land degradation
• 8 Monitoring and evaluating response options
• 9 Involving stakeholders
• 10 Conclusion
• Index