Watching a living planet
The Living Planet Report 2006 describes the changing state of global biodiversity and the pressure on the biosphere arising from human consumption of natural resources. It is built around two indicators: the Living Planet Index, which reflects the health of the planet`s ecosystems; and the Ecological Footprint, which shows the extent of human demand on these ecosystems. These measures are tracked over several decades to reveal past trends, then three scenarios explore what might lie ahead. The scenarios show how the choices we make might lead to a sustainable society living in harmony with robust ecosystems, or to the collapse of these same ecosystems, resulting in a permanent loss of biodiversity and erosion of the planet`s ability to support people.
The Living Planet Index measures trends in the earth`s biological diversity. It tracks populations of 1,313 vertebrate species – fish, amphibians, reptiles, birds, mammals – from all around the world. Separate indices are produced for terrestrial, marine, and freshwater species, and the three trends are then averaged to create an aggregated index. Although vertebrates represent only a fraction of known species, it is assumed that trends in their populations are typical of biodiversity overall. By tracking wild species, the Living Planet Index is also monitoring the health of ecosystems. Between 1970 and 2003, the index fell by about 30%. This global trend suggests that we are degrading natural ecosystems at a rate unprecedented in human history.
Biodiversity suffers when the biosphere`s productivity cannot keep pace with human consumption and waste generation. The Ecological Footprint tracks this in terms of the area of biologically productive land and water needed to provide ecological resources and services – food, fibre, and timber, land on which to build, and land to absorb carbon dioxide (CO2) released by burning fossil fuels. The earth`s biocapacity is the amount of biologically productive area – cropland, pasture, forest, and fisheries – that is available to meet humanity`s needs. Freshwater consumption is not included in the Ecological Footprint; rather it is addressed in a separate section of the report.
Since the late 1980s, we have been in overshoot – the Ecological Footprint has exceeded the earth`s biocapacity – as of 2003 by about 25 per cent. Effectively, the earth`s regenerative capacity can no longer keep up with demand – people are turning resources into waste faster than nature can turn waste back into resources.
Humanity is no longer living off nature`s interest, but drawing down its capital. This growing pressure on ecosystems is causing habitat destruction or degradation and permanent loss of productivity, threatening both biodiversity and human well-being.
For how long will this be possible? A moderate business-as-usual scenario, based on United Nations projections showing slow, steady growth of economies and populations, suggests that by midcentury, humanity`s demand on nature will be twice the biosphere`s productive capacity. At this level of ecological deficit, exhaustion of ecological assets and large-scale ecosystem collapse become increasingly likely.
Two different paths leading to sustainability are also explored. One entails a slow shift from our current route, the other a more rapid transition to sustainability. The Ecological Footprint allows us to estimate the cumulative ecological deficit that will accrue under each of these scenarios: the larger this ecological debt, and the longer it persists, the greater the risk of damage to the planet. This risk must be considered in concert with the economic costs and potential social disruptions associated with each path.
Moving towards sustainability depends on significant action now. Population size changes slowly, and human-made capital – homes, cars, roads, factories, or power plants – can last for many decades. This implies that policy and investment decisions made today will continue to determine our resource demand throughout much of the 21st century.
As the Living Planet Index shows, human pressure is already threatening many of the biosphere`s assets. Even moderate “business as usual” is likely to accelerate these negative impacts. And given the slow response of many biological systems, there is likely to be a considerable time lag before ecosystems benefit significantly from people`s positive actions.
We share the earth with 5-10 million species or more. By choosing how much of the planet`s biocapacity we appropriate, we determine how much is left for their use. To maintain biodiversity, it is essential that a part of the biosphere`s productive capacity is reserved for the survival of other species, and that this share is split between all biogeographic realms and major biomes.
To manage the transition to sustainability, we need measures that demonstrate where we have been, where we are today, and how far we still have to go. The Living Planet
Index and the Ecological Footprint help to establish baselines, set targets, and monitor achievements and failures. Such vital information can stimulate the creativity and innovation required to address humanity`s biggest challenge: how can we live well while sustaining the planet`s other species and living within the capacity of one earth?
Figure 1: Living Planet Index. This shows trends in populations of terrestrial, marine, and freshwater vertebrate species. It declined by 29% from 1970 to 2003.
Figure 2: Humanity`s Ecological Footprint. This estimates how much of the productive capacity of the biosphere people use.
Figure 3: Three Ecological Footprint scenarios. Two may lead to sustainability.
Table 1: Ecological demand and supply. Countries with the highest total footprints.
Living Planet Index
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