August 2005

The Millennium Ecosystem Assessment report was released this year. What did it encompass and why?

Marine species for commercial purposes have been reduced by 90 percent in much of the world. Photo: Olena Sullivan

Samper: The well-being of people depends on ecosystems and the benefits, such as drinkable water, that they provide. However, human impact on the environment has increased. So the United Nations initiated a comprehensive scientific study, the Millennium Ecosystem Assessment, to better comprehend the consequences of recent changes to ecosystems, to propose scenarios for the future, and to suggest actions that might limit damage to ecosystems. Nearly 1,400 experts from 95 countries participated in this assessment.

How does science describe an ecosystem?

Samper: An ecosystem is defined as a habitat where a community of organisms—animals, people, and plants—interact with one another and with their physical environment. It includes other components such as soils, water, and nutrients that support the organisms living in an ecosystem. Human well-being depends on the services provided by ecosystems and their components.

How do ecosystems provide services to humans?

Samper: Ecosystem services are the benefits people receive from ecosystems. We derive basically four kinds of services:

• Provisioning services are things like food, timber, and water
• Regulating services regulate things like climate, floods, and disease
• Supporting services support geochemical and biological processes on Earth, for example, the nutrient cycle and pollination
• Cultural services make a difference for our souls, physical and aesthetic enjoyment, and our communities

How have ecosystems changed in the last 50 years or so?

Samper: One of the findings in the Millennium Ecosystem Assessment is that the ecosystems of the world have changed more rapidly in the last 50 years than at any other point before human history. For instance, we estimate that about 25 percent of the terrestrial continental surface of the planet is currently under some type of cultivation system. In cultivated ecosystems, increased agriculture and the greater use of a few modern varieties of crops have reduced the genetic diversity of domesticated plants and animals.

Other findings of the report include the following:

• We find that degradation has been different in different kinds of ecosystems. We know that the forest ecosystems, both temperate and tropical, have been degraded substantially, whereas in others, like some of the mountain grasslands or savannahs, the impacts have been less. For about half of the ecosystems that we surveyed, more than 50 percent of the total area has been lost in the last 100 years.

• In marine ecosystems, fisheries have declined tremendously because of growing global demand for food and animal feed. Marine species exploited for commercial purposes has been reduced by 90 percent in much of the world since commercial fishing began.

• The number and/or geographical spread of many animal and plant populations have declined. For example, a quarter of mammal species are now under threat of extinction. Human activity is the reason that there have been between 50 and 1000 times more extinctions in the last 100 years than would have occurred naturally.

What are the main causes for these changes?

Samper: The overall main change has been land transformation and habitat degradation, but it really depends on the kind of community or ecosystem that you are looking at. We know that for forest ecosystems and for drylands, land use and land use change have been the most important driver. We know that for island ecosystems the main driver has probably been invasive species. We know that in certain kinds of wetlands and other kinds of ecosystems, pollution and climate change have also had a big impact. So the driver depends on the type of ecosystem.

How do these changes affect biodiversity?

Samper: They affect it in many ways. Partly they have reduced the range of many species. We know that there are many species that have gone extinct locally or globally. We know that the population size of most species is actually decreasing, with the exception of certain species that tend to be invasive. For those particular species, which is a small number, their overall distribution range is increasing worldwide and substantially. But it is not only about the individual species. We find that these changes affect the interactions among them and the functioning of the communities and the ecosystems as well.

And how do these changes affect human well-being?

Samper: Because as humans we have derived so many of our essential elements of our livelihoods from these ecosystems, these changes affect us directly by, say, reducing the access to provisional services like food or fuel or water. But they also affect us to a greater extent, say, by affecting flood regulation. We see that in many parts of the world the number of floods is increasing in direct proportion to deforestation. So there are many indirect effects that come to haunt us.

How can we reverse the degradation of ecosystems?

Samper: There is a range of tools. As a part of the assessment we considered about 70 different kinds of responses. They are grouped in a set of economic steps that need to be taken, primarily through the removal of certain kinds of perverse incentives that promote the unsustainable use of particular kinds of use of ecosystems.

Take the logical solutions that have to do with developing certain kinds of technologies that improve the efficiency of the use of certain ecosystems. Many of these technologies are available; we just need to transfer them faster around the world. We know that there are certain kinds of social incentives and response measures that work, primarily through education, creating awareness, and changing consumption patterns. There is a set of scientific areas where we have important gaps in our understanding that we need to fill, and also institutional measures primarily related to governments and the types of institutions that we have for regulating access to ecosystems and their services.

What are the prospects for ecosystems in the foreseeable future?

Samper: The majority of the scenarios show that there will continue to be important increases in ecosystem loss in the next 30 or 40 years. As part of the assessment we developed four general scenarios looking at the future effects of different kinds of drivers. What we find is that under all scenarios populations will increase substantially in the next 40 to 50 years, but under some, the population will actually start decreasing substantially by the year 2100. And, clearly, what we are finding is that it is not only about limiting the population size but also about how we can use different technologies and market incentives to do this. The good news is that clearly there are many tools that we know will have an impact in terms of improving ecosystem services. What we need to do is just to embrace them and to transfer some of them faster in terms of policies and goodwill.

What are the main conclusions drawn from the assessment?

Samper: The main conclusions are these:

• Clearly, in terms of the status and trends, we have lost important areas of most ecosystems around the world, both terrestrial and marine.

• We know that most of these changes are increasing and the rate of change is increasing, pretty much throughout the world.

• We know that the changes in ecosystems and their services is having a direct impact on the livelihoods of people all over the world. In many parts of the world it is increasing the inequities in terms of affecting disproportionately some of the poorer people.

• We know that some of the changes in ecosystems are generating more and more nonlinear changes. These are changes that we’ll never expect. A good example of that is the fishing industry off the coast of Newfoundland where we know that fishing pressure was so increased that the entire fisheries population crashed. We have not been able to recover that. We are seeing more and more changes like that that are not easily predictable.

• We know that under most of our suggested scenarios ecosystem change will continue but that there are certain scenarios that are clearly better than others for decision makers and others designing plausible futures.

• Last, but not least, we know that there are certain types of responses that we can implement right now to substantially improve ecosystem services and human well-being.

So, all in all, ecosystems have suffered greatly and will continue to suffer greatly unless we undertake a series of measures. The assessment has provided some answers, based on comprehensive investigation, as to the measures we can take. The assessment is only the first step. We must now act to initiate changes that will ensure the well-being of the human race in the future.

© 2005, American Institute of Biological Sciences. Educators have permission to reprint articles for classroom use; other users, please contact editor@actionbioscience.org for reprint permission. See reprint policy.