Biodiversité Perspectives mondiales

1. Why is biodiversity loss a concern?

The source document for this Digest states:

Biological diversity, or biodiversity, is a term used to describe the myriad life forms found on Earth. These are the legacy of billions of years of evolution, shaped by natural processes and, increasingly, by the activities of humans.

Biodiversity is most oft en understood as the number of different species of plants, animals and microorganisms in existence. Our planet is home to millions of species—estimates range from two to over 10 million in total—the majority of which have yet to be identified. However, biodiversity also encompasses the specific genetic variations and traits within species as well as the assemblage of these species within ecosystems. At the genetic level, differences in DNA codes within species give rise to unique types including different varieties of crops and breeds of livestock. Cultivated rice, for instance, belongs to only two species, yet includes over 120,000 genetically distinct varieties. At the ecosystem level, biodiversity refers to the varied assemblages of species that characterize deserts, forests, wetlands, grasslands, lakes, rivers, agricultural and other landscapes. Each ecosystem consists of living creatures interacting with one another and with the air, water, and soil around them. These multiple interconnections within and among ecosystems form the web of life, of which we humans are an integral part and upon which we entirely depend.

It is the combination of life forms and their interactions with one another, and with the physical environment, that has made Earth habitable for humans. Ecosystems provide the basic necessities of life (e.g., food, water and the very air we breathe), offer protection from natural disasters and disease (e.g., by regulating climate, floods and pests), provide a foundation for human cultures and inspire our spiritual beliefs and worldviews. These “ecosystem services” also support and maintain the essential life processes of the planet, such as primary production and nutrient cycling. Each of these supporting services is essential to human well-being, whether the services are considered at the local, regional or global level.

Even as we begin to understand better what is at stake, genes, species and habitats are rapidly being lost. The first comprehensive assessment of the status of the world’s natural resources in terms of their contributions to human life and well-being confirms this. The Millennium Ecosystem Assessment, completed in 2005 by more than 1360 scientists working in 95 countries, found that changes in biodiversity due to human activities were occurring more rapidly in the past 50 years than at any time in human history, and that the direct causes (or drivers) of this loss are either remaining steady, showing no evidence of decline over time, or are increasing in intensity over time. In effect, we are currently responsible for the sixth major extinction event in the history of the Earth, and the greatest since the dinosaurs disappeared, 65 million years ago.

Source & ©: CBD  Global Biodiversity Outlook 2 (2006),
Introduction, p.9-10

Chapter 1

The essential role of biodiversity

The impact of humans on the natural environment is significant and growing. There are currently well over six billion people on the planet; there will likely be nine billion by mid-century. Each person has the right to adequate clean water, food, shelter and energy, the provision of which has profound ecological implications.

Human needs multiplied by a growing world population translate into increasing, and unprecedented, demands on the planet’s productive capacity. The growing appetite for consumer goods and services beyond the necessities of survival and the wasteful consumption of available resources by the more privileged segment of global society are exacerbating the strain on the Earth, with consequences for all. As demographic pressures and consumption levels increase, biodiversity decreases, and the ability of the natural world to continue delivering the goods and services on which humanity ultimately depends may be undermined.

Biodiversity, ecosystem functioning, ecosystem services, and drivers of change

Biodiversity underpins ecosystem functioning. The services provided by healthy ecosystems, in turn, are the foundation for human well-being. These ecosystem services not only deliver the basic material needs for survival, but also underlie other aspects of a good life, including health, security, good social relations and freedom of choice (see Figure 1.1).

The Millennium Ecosystem Assessment examined the state of 24 services that make a direct contribution to human well-being.1 The Assessment concludes that 15 of 24 are in decline, including provision of fresh water, marine fishery production, the number and quality of places of spiritual and religious value, the ability of the atmosphere to cleanse itself of pollutants, natural hazard regulation, pollination, and the capacity of agricultural ecosystems to provide pest control.

By disrupting ecosystem functions, biodiversity loss makes ecosystems more vulnerable to shocks and disturbances, less resilient, and less able to supply humans with needed services. The damage to coastal communities from floods and storms, for example, can increase dramatically following conversion of wetland habitats, as the natural protection offered by these ecosystems against wave action, tidal surge, and water run-off from land is compromised. Recent natural disasters underline this reality (see Box 1.1).

Healthy ecosystems are critical to human well-being at all times, not only in times of catastrophe. For example, inland wetlands are the principal source of renewable fresh water for human use, storing water but also purifying it through the removal of excess nutrients and other pollutants. Disruption of wetland purification processes can have devastating impacts at the source and further downstream. The loss of wetlands in the Mississippi watershed of the United States, for example, combined with high nutrient loads from intensive agriculture in the region, has contributed to the creation of a low-oxygen “dead zone”, incapable of supporting animal life, which extends, on average at mid-summer, some 16,000 square kilometres into the Gulf of Mexico.

The consequences of biodiversity loss and ecosystem disruption are oft en harshest for the rural poor, who depend most immediately upon local ecosystem services for their livelihoods and who are often the least able to access or afford substitutes when these become degraded. In daily life, rural households depend, to varying degrees, on farming, fishing, hunting and the harvest of wild products to help meet their subsistence and cash needs, complementing this environmental income with outside sources of earnings, such as wage labour or remittances. In times of crisis—during a drought or economic recession, for example—even those households not normally reliant on environmental income can turn to wild products as a last resort. Ecosystems then serve the additional function of social safety nets, insuring families against absolute poverty and starvation.

Box 1.1 The role of biodiversity in mitigating the impacts of natural disasters

Economic benefits under alternativemanagement practices

The marginal position of rural communities in society oft en allows more powerful interests to capture ecosystem benefits for private gain, frequently through the conversion of ecosystems to other uses. Although studies are few, in every case examined where the total economic value (i.e., market and non-market value combined) of ecosystems under alternative management regimes were compared, managing the ecosystem more sustainably yielded greater total benefits than conversion (Figure 1.2). In one of these studies, for instance, intact mangrove ecosystems along Thailand’s coast were found to provide substantial benefits to society as a source of timber and non-timber forest products, in the production of charcoal, and by enhancing offshore fisheries and providing storm protection. When mangroves were converted to make way for private shrimp farms, these societal benefits fell to almost zero. Conversion of the natural ecosystem proceeded nonetheless, in part because those individuals standing to gain immediate private benefits did not have to bear the costs associated with the loss of ecosystem services. In some cases, government subsidies can exaggerate the private benefits of conversion, as ecosystems are degraded at public expense. The end result for the poor is further disenfranchisement.

Garnering the political will to halt ecosystem degradation will depend on clearly demonstrating to policy makers and society at large the full contribution made by ecosystems to national economies. A recent World Bank report estimates that natural capital, even when defined narrowly, constitutes a quarter (26%) of the total wealth(greater than the share of produced capital) of low-income countries. The report also suggests that better management of ecosystems and natural resources will be key to sustaining development while nations build other forms of wealth (i.e., infrastructure, but also human and institutional capital). Specific examples of the economic value derived from biodiversity are also available, and are increasing in number (see Box 1.2).

However, a more profound re-thinking of economic growth, and how it is measured, is also needed. Current measures of economic wealth, such as the gross domestic product (GDP), do not reflect the total economic value of ecosystems, and mistakenly treat nature’s goods and services as free to use and limitless in abundance. As a result, countries that fell their forests for timber exports, dynamite reefs for fish, and degrade their land as a result of unsustainable agriculture can appear to be getting richer in the short-term. Applying better valuation methods to national economies, as indicated in the case study on conversion of mangrove to aquaculture in Thailand, would reveal that for many countries, and in a number of sectors, economic gains as traditionally measured are illusory.

World Bank figures suggest that, per capita, most low-income countries have experienced declines in both total and natural capital, jeopardizing both economic growth and the achievement of the Millennium Development Goals (MDGs) (see Box 1.3). In fact, the Millennium Ecosystem Assessment has already confirmed that the real costs of biodiversity loss pose a significant barrier to meeting the MDGs. Although policy-makers have generally focused narrowly on the contribution of biodiversity conservation and sustainable use to the achievement of Goal 7 (“Ensure environmental sustainability”), the wider role of ecosystem services in supporting livelihoods and human well-being reveals biodiversity to be the foundation for all development, and hence for meeting each of the Millennium Development Goals. Studies of food security and nutrition, for instance, have shown the importance of agricultural biodiversity to the elimination of hunger and malnutrition. In terms of human health, biodiversity also has a recognized role in controlling vector-based diseases and providing the natural sources of many traditional medicines and modern pharmaceutical drugs.

The challenge ahead of us lies in the fact that a number of the actions that could be implemented most quickly to promote economic growth and reduce hunger and poverty (e.g., intensification of agriculture or infrastructure developments) are harmful to biodiversity, at least in the short- to medium-term, and could undermine the sustainability of any development gains. Recognizing the trade-offs and synergies that exist between poverty alleviation, biodiversity conservation and sustainable use will therefore be essential to achieving many of the targets of the Millennium Development Goals, as discussed further in Chapter 4.

There are important additional reasons to care about the loss of biodiversity, quite apart from nature’s immediate usefulness to humankind. Many would argue that every life form has an intrinsic right to exist. Species alive today are thousands to millions of years old and have each travelled unique evolutionary paths, never to be repeated, in order to reach their present form. We must also recognize the right of future generations to inherit, as we have, a planet thriving with life, and that continues to afford opportunities to reap the economic, cultural and spiritual benefits of nature.

Box 1.2 Contribution of ecosystem goods and services to national economies

Box 1.3 Millennium Development Goals

Source & ©: CBD  Global Biodiversity Outlook 2 (2006),
Chapter 1:The Essential role of Biodiversity, p.13-19