文章 Articles

Watching a living planet

Humans are living beyond their means, says the WWF's Living Planet Report 2006. But we can still limit our consumption habits before the earth is damaged irreversibly. chinadialogue presents an excerpt from the biennial report.
Article image

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?

WWF Living Planet Index

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

The Living Planet Index is a measure of the state of the world’s biodiversity based on trends from 1970 to 2003 in over 3,600 populations of more than 1,300 vertebrate species from around the world. It is calculated as the average of three separate indices that measure trends in populations of 695 terrestrial species, 274 marine species, and 344 freshwater species.

The index shows an overall decline of around 30% over the 33-year period, as do each of the terrestrial, marine, and freshwater indices individually. The decline in the indices, and in particular the freshwater index, is less than in previous reports, because the indices have been aggregated in a different way, designed to reduce the degree of uncertainty around them

No attempt is made to select species on the basis of geography, ecology, or taxonomy, so the index dataset contains more population trends from well researched groups, especially birds, and well-studied regions, particularly Europe and North America. In compensation, temperate and tropical regions are given equal weight (with equal weight to each species in each region) within the terrestrial and freshwater indices, and to ocean basins within the marine index.

Figure 4: Terrestrial Living Planet Index. The terrestrial species index shows a 31% decline on average from 1970 to 2003.

Figure 5: Marine Living Planet Index. The marine species index shows an average decline of 27% between 1970 and 2003.

Figure 6: Freshwater Living Planet Index. The freshwater species index declined byapproximately 28% between 1970 and 2003.


Ecological Footprint
 
The Ecological Footprint measures humanity’s demand on the biosphere in terms of the area of biologically productive land and sea required to provide the resources we use and to absorb our waste. In 2003 the global Ecological Footprint was 14.1 billion global hectares, or 2.2 global hectares per person (a global hectare is a hectare with world-average ability to produce resources and absorb wastes). The total supply of productive area, or biocapacity, in 2003 was 11.2 global hectares, or 1.8 global hectares per person.

The footprint of a country includes all the cropland, grazing land, forest, and fishing grounds required to produce the food, fibre, and timber it consumes, to absorb the wastes emitted in generating the energy it uses, and to provide space for its infrastructure.

People consume resources and ecological services from all over the world, so their footprint is the sum of these areas, wherever they may be on the planet.

Humanity’s footprint first grew larger than global biocapacity in the 1980s; this overshoot has been increasing every year since, with demand exceeding supply by about 25% in 2003. This means that it took approximately a year and three months for the earth to produce the ecological resources we used in that year.

Separating the Ecological Footprint into its individual components demonstrates how each one contributes to humanity’s overall demand on the planet. Figure 19 tracks these components in constant 2003 global hectares, which adjust for annual changes in the productivity of an average hectare. This makes it possible to compare absolute levels of demand over time. The CO2 footprint, from the use of fossil fuels, was the fastest growing component, increasing more than ninefold from 1961 to 2003.

How is it possible for an economy to continue operating in overshoot? Over time, the earth builds up ecological assets, like forests and fisheries. These accumulated stocks can, for a limited period, be harvested faster than they regenerate. CO2 can also be emitted into the atmosphere faster than it is removed, accumulating over time.

For three decades now we have been in overshoot, drawing down these assets and increasing the amount of CO2 in the air. We cannot remain in overshoot much longer without depleting the planet’s biological resources and interfering with its long-term ability to renew them.

Figure 19: Ecological Footprint by component. The footprint is shown in constant 2003 global hectares. In both diagrams, hydropower is included in the builtup land footprint and fuelwood within the forest footprint.

Now more than ever…

chinadialogue is at the heart of the battle for truth on climate change and its challenges at this critical time.

Our readers are valued by us and now, for the first time, we are asking for your support to help maintain the rigorous, honest reporting and analysis on climate change that you value in a 'post-truth' era.

Support chinadialogue

发表评论 Post a comment

评论通过管理员审核后翻译成中文或英文。 最大字符 1200。

Comments are translated into either Chinese or English after being moderated. Maximum characters 1200.

评论 comments

Default avatar
匿名 | Anonymous

降低消耗

我们正面临这样的紧要关头——降低我们的生态足迹,也就是我们的消耗水平。在中国以及世界上的其他地方,一个面向读者的开放性问题是:你在努力这样做吗?这样做有意义吗?对于我来说,我已经在尽可能地做到回收利用,而且准备放弃乘飞机。其他读者在做什么呢?你认为我能做到的最重要的事情是什么呢?

Reducing consumption

We are faced with the urgency of reducing our ecological footprint - our own consumption levels. An open question to readers in China and the rest of the world, then: are you trying to do this? How? And is there any point? As for me, I have been trying to recycle as much as possible, and want to give up air travel. What are other readers doing? What is the most important thing I could do, do you think?

Default avatar
匿名 | Anonymous

减低消耗

我们一部分人进行再生活动, 尝试着使用公共交通工具, 到离家不远的地方度假。然而,我们的朋友却让你有些 “强迫性” 感觉, 那就是当你问他什么洗碗机还未满就启动了呢。以缩小空间及减少能量需求为理由而选择小型房子, 这构思相当正确吧? 无可否认的是, 我们正处于环境实验的启蒙时代。物质的安慰对我们是那么的重要直到我们察觉不到机动车辆、洗碗机、过热的住所及达尔富尔(Durfur)在频道报告中所说的连带关系。联合国农粮组织的报告中指出, 每天有两万五千人死于饥荒, 及史端对《气候变化的经济事务》的报告书所说。然而, 我们还不醒悟, 或者变本加厉: 这是我们所选择的。直到我们察觉事情的紧急性, 政治家们却认为我们丝毫不关心而不接受激进的的改变,然而他们依旧徘徊在那极限中。世界野生动物基金会的足迹分析与潘岳(27/10/06)所发表评论对消耗、污染及需要建议”新款式工业化”,和所提倡对消耗的新形式息息相关。中国的领袖更是明确知道不可能跟随”西式”的生活方式。但是,对与我们怎样生活和如何关系这个世界, 想必, 我们有不同的想法。- Viola Violante 里斯本

Reducing consumption

Some of us recycle a bit, try to take public transport, take holidays closer to home. But then our friends find you a bit ‘obsessive’ when you asked them why they used a dishwasher when only half full. The idea of choosing a house that is smaller, to reduce space and energy demands sounds positively mad right? We are still in the pre-environmental enlightenment era, no doubt about that. Our material comfort is so important to us we cannot see the link between our car(s), dishwashers, over-heated homes and the television reports on Darfur, FAO’s advert saying that 25000 people die of hunger every day, and the Stern report on climate change. We are still fast asleep, or worse: we choose to be. And until we reach a sense of priority and urgency, our politicians will think the people do not care and will not accept radical changes, and they will keep fiddling on the margins.
WWF's footprint analysis links well with Pan Yue's comment (27/10/06) on consumption, pollution and the need to propose a 'new type of industrialisation', and his work advocating new patterns of consumption. China’s leaders are amongst very few talking explicitly about the impossibility to follow the ‘western’ mode of life. Yet we all need to think very differently about how we live and relate to this world.
Viola Violante, Lisbon

Default avatar
匿名 | Anonymous

节约资源

我们也许不能让所有的人在一夜之间能够做到,但我想我还是能让我周围的人明白这一切。资源的过度消耗已经是我们都必须面对的,还等什么?让我们提醒每一个忘记关灯,水龙头的人吧。想信我们是能够做到的———Hanson C K

Mind the resources

We might not be able to persuade everyone overnight, but I think I can at least influence the people around me. Excessive consumption of resources is already what we have to confront now. Why don't we start action right away? Let us remind everyone to turn off the light and to stop extra water from running out of the tap. I believe we should be able to do that.

-------Hanson C K