Ecosystems and Human Well-Being: Volume 1: Current State and Trends: Preface

September 7, 2011, 5:19 am
Source: Millennium Ecosystem Assessment
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This is part of the Millennium Ecosystem Assessment report Ecosystems and Human Well-Being: Volume 1: Current State and Trends


The Current State and Trends assessment presents the findings of the Condition and Trends Working Group of the Millennium Ecosystem Assessment. This volume documents the current condition and recent trends of the world’s ecosystems, the services they provide, and associated human well-being around the year 2000. Its primary goal is to provide decision-makers, ecosystem managers, and other potential users with objective information and analyses of historical trends and dynamics of the interaction between ecosystem change and human well-being. This assessment establishes a baseline for the current condition of ecosystems at the turn of the millennium. It also assesses how changes in ecosystems have affected the underlying capacity of ecosystems to continue to provide these services in the near future, providing a link to the ScenariosWorking Group’s report. Finally, it considers recent trends in ecosystem conditions that have been the result of historical responses to ecosystem service problems, providing a link to the Responses Working Group’s report.

Although centered on the year 2000, the temporal scope of this assessment includes the ‘‘relevant past’’ to the ‘‘foreseeable future.’’ In practice, this means analyzing trends during the latter decades of the twentieth century and extrapolating them forward for a decade or two into the twenty-first century. At the point where the projections become too uncertain to be sustained, the Scenarios Working Group takes over the exploration of alternate futures.

The Condition and Trends assessment aims to synthesize and add to information already available from other sources, whether in the primary scientific literature or already in assessment form. In many instances this information is not reproduced in this volume but is built upon to report additional findings here. So this volume does not, for example, provide an assessment of the science of climate change per se, as that is reported in the findings of the Intergovernmental Panel on Climate Change, but the findings of the IPCC are used here as a basis to present information on the consequences of climate change for ecosystem services. A summary of the process leading to this document is provided in Figure A.

The document has three main parts plus a synthesis chapter and supporting material. (See Figure B.) After the introductory material in Part I, the findings from the technical assessments are presented in two orthogonal ways: Part II deals with individual categories of ecosystem services, viewed across all the ecosystem types from which they are derived, while Part III analyses the various systems from which bundles of services are derived. Such organization allows the chapters to be read as standalone documents and assists readers with thematic interests. In Part IV, the synthesis chapter pulls out the key threads of findings from the earlier parts to construct an integrated narrative of the key issues relating ecosystem change (through changes in ecosystem services) to impacts on human well-being.

Part I: General Concepts and Analytical Approaches

The first part of this report introduces the overarching conceptual, methodological, and crosscutting themes of the MA integrated approach, and for this reason it precedes the technical assessment parts. Following the executive summary of the MA conceptual framework volume (Ecosystems and Human Well-being: A Framework for Assessmentt), which is Chapter 1, the analytical approaches to a global assessment of ecosystems and ecosystem services are outlined in Chapter 2. Chapter 3 provides a summary assessment of the most important changes in key indirect and direct drivers of ecosystem change over the last part of the twentieth century, and considers some of the key interactions between these drivers (the full assessment of drivers, of which this chapter is a summary, can be found in the Scenarios volume, Chapter 7). The remaining chapters in Part I—on biodiversity Chapter 4), human well-being (Chapter 5), and vulnerability (Chapter 6)—introduce issues at a global scale but also contain a synthesis of material drawn from chapters in Parts II and III.

Each of these introductory overarching chapters aims to deal with the general issues related to its topic, leaving the specifics embedded in later chapters. This is intended to enhance readability and to help reduce redundancy across the volume. For example, Chapter 2 seeks to give an overview of the types of analytical approaches and methods used in the assessment, but not provide a recipe for conducting specific assessments, and Chapter 3 aims to provide the background to the various drivers that would otherwise need to be discussed in multiple subsequent chapters.

Biodiversity provides composition, structure, and function to ecosystems. The amount and diversity of life is an underlying necessity for the provision of all ecosystem services, and for this reason Chapter 4 is included in the introductory section rather than as a chapter in the part on ecosystem services. It outlines the key global trends in biodiversity, our state of knowledge on biodiversity in terms of abundance and distribution, and the role of biodiversity in the functioning of ecosystems. Later chapters consider more fully the role of biodiversity in the provision of ecosystem services.

The consequences of ecosystem change for human well-being are the core subject of the MA. Chapter 5 presents our state of knowledge on the links between ecosystems and human well-being and outlines the broad patterns in well-being around the world. Neither the distribution of ecosystem services nor the change in these services is evenly distributed across places and societies. Certain ecosystems, locations, and people are more at risk from changes in the supply of services than others. Chapter 6, on vulnerable peoples and places, identifies these locations and groups and examines why they are particularly vulnerable to changes in ecosystems and ecosystem services.

Part II: An Assessment of Ecosystem Services

The Condition and Trends assessment sets out to be comprehensive in its treatment of ecosystem services but not exhaustive. The list of ‘‘benefits that people derive from ecosystems’’ grows continuously with further investigation. The 11 groups of services covered by this assessment deal with issues that are of vital importance almost everywhere in the world and represent, in the opinion of the Working Group, the main services that are most important for human well-being and are most affected by changes in ecosystem conditions. The MA only considers ecosystem services that have a nexus with life on Earth (biodiversity). For example, while gemstones and tidal energy can both provide benefits to people, and both are found within ecosystems, they are not addressed in this report since their generation does not depend on the presence of living organisms. The ecosystem services assessed and the chapter titles in this part are:

Provisioning services:

Regulating and supporting services:

Cultural services:

Each of the chapters in this section in fact deals with a cluster of several related ecosystem services. For instance, the chapter on food covers the provision of numerous cereal crops, vegetables and fruits, beverages, livestock, fish, and other edible products; the chapter on nutrient cycling addresses the benefits derived from a range of nutrient cycles, but with a focus on nitrogen; and the chapter on cultural and amenity services covers a range of such services, including recreation, aesthetic, and spiritual services. The length of the treatment afforded to each service reflects several factors: our assessment of its relative importance to human well-being; the scope and complexity of the topic; the degree to which it has been treated in other assessments (thus reducing the need for a comprehensive treatment here); and the amount of information that is available to be assessed.

Part II considers services from each of the four MA categories: provisioning, regulating, cultural, and supporting services. Each service chapter has been developed to cover the same types of information. First the service is defined. Then, for each service, the spatial distribution of supply and demand is quantified, along with recent trends. The direct and indirect drivers of change in the service are analyzed. And finally the consequences of the changes in the service for human well-being are examined and quantified to the degree possible.

Examples are given of the responses by decision-makers at various levels (from the individual to the international) to issues relating to change in service supply. Both successful and unsuccessful interventions are described, as supportive material for the Policy Responses volume.

Part III: An Assessment of Systems from which Ecosystem Services Are Derived

The Condition and Trends Working Group uses the term ‘‘systems’’ in describing these chapters rather than the term ‘‘ecosystems.’’ This is for several reasons. First, the ‘‘systems’’ used are essentially reporting units, defined for pragmatic reasons. They represent easily recognizable broad categories of landscape or seascape, with their included human systems, and typically represent units or themes of management or intervention interest. Ecosystems, on the other hand, are theoretically defined by the interactions of their components.

The 10 selected systems assessed here cover much larger areas than most ecosystems in the strict sense and include areas of system type that are far apart (even isolated) and that thus interact only weakly. In fact, there may be stronger local interactions with embedded fragments of ecosystems of a different type rather than within the nominal type of the system. The ‘‘cultivated system,’’ for instance, considers a landscape where crop farming is a primary activity but that probably includes, as an integral part of that system, patches of rangeland, forest, water, and human settlements. Second, while it is recognized that humans are always part of ecosystems, the definitions of the systems used in this report take special note of the main patterns of human use. The systems are defined around the main bundles of services they typically supply and the nature of the impacts that human use has on those services. Information within the systems chapters is frequently presented by subsystems where appropriate. For example, the forest chapter deals separately with tropical, temperate, and boreal forests because they deliver different services; likewise, the coastal chapter deals explicitly with various coastal subsystems, such as mangroves, corals, and seagrasses.

The 10 system categories and the chapter titles in this part are:

Definitions for these system categories can be found in Box 1.3 in Chapter 1. These system categories are not mutually exclusive, and some overlap spatially. For instance, mountain systems contain areas of forest systems, dryland systems, inland water systems, cultivated systems, and urban systems, while coastal systems include components of all of the above, including mountain systems. Due to this overlap, simple summations of services across systems for global totals should be avoided (an exercise that the MA has avoided in general): some may be double-counted, while others may be underrepresented. Notwithstanding these caveats, the systems have been defined to cover most of the Earth’s surface and not to overlap unnecessarily. In many instances the boundaries between systems are diffuse, but not arbitrary. For instance, the coastal system blends seamlessly into the marine system on the one hand and the land systems on the other. The 50-meter depth distinction between coastal and marine separates the systems strongly influenced by actions on the land from those overwhelmingly influenced by fishing.

There is significant variation in the area of coverage of each system. The system definitions are also not exhaustive, and no attempt has been made to cover every part of the global surface. Although 99% of global surface area has been covered in this assessment, there are just over 5 million square kilometers of terrestrial land surface not included spatially within any of the MA system boundaries. These areas are generally found within grassland, savanna, and forest biomes, and they contain a mix of land cover classes— generally grasslands, degraded forests, and marginal agricultural lands—that are not picked up within the mapping definitions for the system boundaries. However, while these excluded areas may not appear in the various statistics produced along system boundaries, the issues occurring in these areas relating to ecosystem services are well covered in the various services chapters, which do not exclude areas of provision outside MA system boundaries.

The main motivation for dealing with ‘‘systems’’ as well as ‘‘services’’ is that the former perspective allows us to examine interactions between the services delivered from a single location. These interactions can take the form of trade-offs (that is, where promoting one service reduces the supply of another service), win-win situations (where a single management package enhances the supply of several services), or synergies, where the simultaneous use of services raises or depresses both more than if they were independently used.

The chapters in Part III all present information in a broadly similar manner: system description, including a map and descriptive statistics for the system and its subsystems; quantification of the services it delivers and their contribution to well-being; recent trends in the condition of the system and its capacity to provide services; processes leading to changes in the system; the choices and resultant trade-offs between systems and between services within the system; and the contributions of the system to human well-being.

Part IV: Synthesis

Chapter 28 does not intend to be a summary. That task is left to the summaries or Main Messages of each chapter and to the Summary at the start of this volume. Instead, the synthesis chapter constructs an integrated narrative, tracing the principal causes of ecosystem change, the consequences for ecosystems and ecosystem services, and the resultant main impacts on human wellbeing.

The chapter considers the key intellectual issues arising from the Condition and Trends assessment and presents an assessment of our underlying knowledge on the consequences of ecosystem change for people.

Supporting material for many of the chapters, and further details of the Millennium Ecosystem Assessment, including of the various sub-global assessments, plus a full list of reviewers, can be found at the MA Web site at

Rashid Hassan
University of Pretoria, South Africa

Robert Scholes
Council for Science and Industrial Research, South Africa

Neville J. Ash
UNEP-World Conservation Monitoring Centre


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This is a chapter from Ecosystems and Human Well-Being: Volume 1: Current State and Trends.
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