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Indicators in Practice

Dec 17, 2014

Living Planet Report

Last month, the WWF released a particularly sobering finding: worldwide populations of vertebrate species have been cut in half in the past four decades. This assessment was presented as part of WWF's 2014 Living Planet Report, which documents the pressures that humans are exerting on the world’s ecosystems.
Gray wolves in Yellowstone National Park (Doug Smith via Wikimedia Commons)

Case Study: Living Planet Report

Scope: Global

Released: 2014 (tenth edition)

Intended Audience: General public; wildlife and environmental managers; national governments

Potential Application: Raising public awareness about declines in species populations and ecosystem service availability; helping policymakers and decisionmakers set ecological management priorities

Developer: WWF, in collaboration with the Global Footprint Network, Water Footprint Network, and Zoological Society of London


The tenth edition of WWF's Living Planet Report presents a series of three indices that measure the status of the planet in terms of human impacts and natural capital. These three indicators—the Living Planet Index, the Ecological Footprint, and the Water Footprint—collectively provide metrics for the status of worldwide species populations and for how humans are using and consuming the world's resources.

In addition to describing these indicators, the full report includes an overview of additional environmental indicators, provides case studies and specific examples about how humans are using the resources around the world, and makes a compelling case for why we should care about environmental metrics such as those presented in the report, including a discussion of equity issues that are framed by the report’s findings.

Bluefin tuna in the Atlantic Ocean (NOAA/Marine Photobank)

Living Planet Index

The flagship assessment of the Living Planet Report is its Living Planet Index (LPI), which provides an indicator for the status of the world’s species by evaluating a subset of vertebrate populations from every biogeographic region. This year, the global LPI reveals that the size of vertebrate populations declined by 52% between 1970 and 2010. Broken down by taxonomic group, populations of freshwater species fell by 76%, while both marine and terrestrial species populations declined by 39%. Notably, this is a more drastic decline than was reported in previous versions of the LPI. The discrepancy is due to improved methodologies utilized in this version of the index—specifically the inclusion of more information from outside North American and Europe to minimize data skewing by over-representation of these two continents.

Figure 1. The Living Planet Index shows troubling trends for middle and low income countries (2014 Living Planet Report).

The 2014 LPI is based on information from 10,380 vertebrate populations representing just over 3,000 species of fish, amphibians, reptiles, birds, and mammals. While the exclusive focus on vertebrates is not representative of the global suite of species, the authors chose to focus on this taxonomic group because they are well-studied and have an abundance of data available on population trends over time.

The index also presents information on the most significant threats to the species evaluated, derived directly from the data sources used to assess population status. The three primary drivers of population decline are exploitation (threatening 37% of species), habitat change and degradation (31% of species) and habitat loss (13.4% of species). Currently, climate change ranks fourth, threatening 7.1% of species, but the authors note that this driver is expected to worsen in impact as the effects of a warming climate continue to mount.

The LPI is an interesting indicator because it does not address species extinctions outright—rather, it evaluates the status of individual species populations, which can serve as an important barometer for broader questions about ecosystem health and overall species status. Most species exist in a number of individual populations around the world, and will not go globally extinct unless every single population disappears. However, “local extinction,” or the disappearance of a single population, can still  have dramatic effects on ecosystem—for example, we would not necessarily worry about the global extinction of beavers if they only disappeared from New England, but that disappearance would still cause significant changes to wetland ecosystems in this part of the world. Conservation biologists also care about individual species populations because of the information they provide about the overall species; if we knew that every beaver population in the world was declining, we might start to worry about eventual global extinction.  The LPI thus offers insight into a key aspect of biodiversity around the world.

Ecological Footprint

A second major component of the Living Planet Report is its Ecological Footprint assessment, which measures the area of land and water required to provide the ecosystem services on which humans depend. The report finds that we are using ecological goods and services at a rate faster than they are being replenished—in other words, human demands on natural resources are exceeding the biocapacity of the planet. At current rates of consumption, the report finds that humans would need 1.5 Earths to continue providing enough resources into the future.

The report measures both ecological footprint and biocapacity in a common unit called a global hectare (gha). Six categories of “footprints,” or the area in hectares needed to meet current demands for different resources, are calculated using data from the Global Footprint Network: carbon, fishing grounds, cropland, built-up lands, forest products, and grazing products. Yearly footprint values since 1961 are reported, revealing a trend of steadily-increasing resource demands. This trend is pronounced for carbon, whose footprint has risen sharply over the last five decades. Regional and national-level footprints are also provided. Unsurprisingly the largest footprints lie within North American and Europe. The footprints of the top five countries make up roughly half of the world’s total ecological footprint.

This last finding underscores the important inequality with which many of us are already familiar: poorer, developing countries have relatively small ecological footprints, yet often bear the brunt of the damage from environmental degradation worldwide.

Figure 2. The Ecological Footprint of high income countries has consistently exceeded the world's biocapacity for decades (2014 Living Planet Report).

Water Footprint

The final index in the Living Planet Report is the Water Footprint, which is similar in concept to the Ecological Footprint but focuses exclusively on water use around the globe. This footprint focuses exclusively on national-level water usage and considers three discrete types of use: Green water, or the volume of soil water that is evaporated through crop growth; blue water, or the volume of freshwater taken from lakes, rivers, reservoirs, and aquifers that is not returned back to the system; and grey water, or the volume of water that is polluted by industrial and agricultural processes and by wastewater from household use. India, the United States, and China take the lead with the top three water footprints in the world. The rankings also report on the ratio of green to blue water in each country, which provides an indication of the risk of water scarcity in particular nations.

Significance of the Living Planet Report

The Living Planet Report in its entirety is notable because of its predication on an increasingly recognized concept in environmental management: the idea of ecosystem services, or the goods and services that are provided to people by the world’s environment. This is an intuitive concept that is increasingly being developed through economic analysis and ecosystem science, but we are still a long way from fully understanding exactly how we are using these services, let alone how to accurately value them. The Living Planet Report does not address the economic question of how to value ecosystem services, nor does it detail the specific mechanics of how ecosystem function relates to ecosystem services; however, by focusing on measurements of human use of natural resources through the Ecological and Water Footprints, the report is implicitly underscoring the fact that humans depend on these ecosystem functions for basic needs like water provisioning, agriculture, and energy production. In this sense, the Living Planet Report helps illustrate the pervasive importance of ecosystem services to human well-being.