Overview
Overall declines in terrestrial, marine, and freshwater animal populations; declines in tropical forests, dryland systems, and grasslands; declines in Neotropical, Afrotropical, and Indo-Pacific regions; declines in birds and mammals.
Living Planet Index
The Living Planet Index is an indicator designed to monitor the state of the world’s biodiversity. Specifically, it tracks trends in a large number of populations of species in much the same way that a stock market index tracks the value of a set of shares or a retail price index tracks the cost of a basket of consumer goods. The Living Planet Index is based on trends in nearly 5,000 populations of 1,686 species of mammal, bird, reptile, amphibian and fish from around the globe. The changes in the population of each species are then averaged and shown relative to 1970, which is given a value of 1.0.
The global Living Planet Index is the aggregate of two indices – temperate (which includes polar) and tropical – each of which is given equal weight. In the tropical and temperate indices, the overall trends in terrestrial, freshwater and marine species are also each given equal weight.
The tropical index consists of terrestrial and freshwater species populations found in the Afrotropical, Indo-Pacific and Neotropical realms as well as marine species populations from the zone between the Tropics of Cancer and Capricorn. Terrestrial, freshwater, and marine species average trends are given equal weight in computing this index. The index shows a -51 per cent overall trend from 1970 to 2005 in 1,333 populations of 585 species.
The temperate index includes terrestrial and freshwater species populations from the Palearctic and Nearctic realms as well as marine species populations north or south of the tropics. Terrestrial, freshwater, and marine species average trends are given equal weight in computing this index. The index shows a +6 per cent average trend between 1970 and 2005 in 3,309 populations of 1,235 species.
The global index shows an overall
decline from 1970 to 2005 of nearly 30 per cent (Figure 5). The
tropical index fell by about 50 per cent while the temperate index
showed little overall change over the same period (Figures 6 and
7). This marked contrast in trends between temperate and
tropical populations is apparent in terrestrial, freshwater and
marine species. It does not necessarily imply, however, that
tropical biodiversity is in a far worse state than temperate
biodiversity. If
the index were to extend back centuries
rather than decades, it might well show a decline of equal or
greater magnitude among temperate species populations.
Whether or not this is the case, the index shows that there is a
severe and ongoing loss of biodiversity in tropical
ecosystems.
The figure below tracks the tropical index and temperate index, as well as their aggregated index, the Living Planet Index, over the period 1970 through 2005. During this period, there was a -51% overall trend in 1,333 populations of 585 species.
Source: Table 2: The Living Planet Index, Ecological Footprint, Biocapacity and Water Footprint Through TIme, 1961-2005. in The Living Planet Report 2008. © 2008 World Wildlife Fund for Nature, Gland Switzerland. With contributions from the Zoological Society of London and Global Footprint Network. ISBN: 978-2-88085-292-4. Downloadable from http://www.footprintnetwork.org/en/ind ex.php/GFN/page/living_planet_report/.
Terrestrial, Marine, and Freshwater Indexes
The terrestrial, freshwater and marine indices are each calculated as the average of two indices which separately measure trends in tropical and temperate vertebrate populations.
The terrestrial index has declined consistently since the mid-1970s, and shows an average 33 per cent decline in terrestrial vertebrate populations between 1970 and 2005 in 2,007 populations of 887 terrestrial species. Most of this change took place in the tropics; there was little overall change in species populations in temperate regions. In the tropics, a combination of deforestation and other habitat destruction, driven by agricultural conversion and overexploitation from logging and hunting, are among the major causes of species population declines.
The marine index shows an average overall decline of 14 per cent between 1970 and 2005 in 1,175 populations of 341 marine species. Rising sea temperatures, destructive fishing methods and pollution are responsible for some of the decline in marine life. A recent study shows that 40 per cent of the world’s oceans are severely affected by human activities. Overfishing is the major driver of this change, with most of the world’s commercial marine fisheries believed to be fully exploited or overexploited. Oceans provide vital resources and ecosystem services upon which all life depends; however, marine protected areas currently cover less than 1 per cent of the world’s seas. Recent assessments show that population declines extend beyond vertebrates. For example, decline in coral abundance due to bleaching and disease, driven by increasing sea surface temperatures, is of growing concern.
Inland waters are home to an enormous diversity of species and also provide resources and ecological services that are essential to human well-being. The freshwater index shows that populations of species in inland waters decreased on average by 35 per cent from 1970 to 2005 in 1,463 populations of 458 species. It is estimated that wetland areas decreased in extent by 50 per cent during the 20th century as a result of a number of different threats. Loss and degradation of wetlands is caused by overfishing, invasive species, pollution, creation of dams and water diversion.
Source: Table 2: The Living Planet Index, Ecological Footprint, Biocapacity and Water Footprint Through TIme, 1961-2005. in The Living Planet Report 2008. © 2008 World Wildlife Fund for Nature, Gland Switzerland. With contributions from the Zoological Society of London and Global Footprint Network. ISBN: 978-2-88085-292-4. Downloadable from http://www.footprintnetwork.org/en/ind ex.php/GFN/page/living_planet_report/.
Biomes
The indices below highlight species population declines in three groups of biomes that are subject to intense local and global pressures. If degradation continues at current rates, the loss of ecosystem services such as water purification and climate regulation will have serious repercussions for both human well-being and biodiversity.
Tropical forests support a wide diversity of species and provide globally and locally important ecosystem services. This habitat and its species are under threat from pressures such as deforestation, illegal logging, forest fire and climate change. Deforestation continues in the tropics, with primary forest disappearing at the rate of almost 3.5 million hectares per year in Brazil and 1.5 million hectares per year in Indonesia over the period 2000 to 2005. This is reflected in the tropical forest index, which reveals a decline of 62 per cent in 503 animal populations of 186 species.
Species populations in dryland systems have declined by about 44 per cent since 1970 for the 476 populations of 149 species studied. Drylands make up more than 40 per cent of the Earth’s terrestrial system, including such diverse ecosystems as deserts, savannah and tropical dry woodlands. Drylands are also home to over 2 billion people whose livelihoods often depend directly on local ecosystem goods and services. While the addition of water points to dryland systems has permitted increased numbers of livestock for the short-term benefit of humans, this has had a negative impact on fragile systems, to the detriment of biodiversity. An estimated 20 per cent of dryland areas now suffer soil degradation.
Grasslands, found on all continents other than Antarctica, have declined in quality and extent over past decades with high rates of conversion to agriculture. Humans are reliant on grasslands both directly for food and indirectly through ecosystem services such as nutrient cycling. Grasslands also support a wide range of natural diversity, from endemic plant species to grazing mammals such as antelopes, populations of which are vital for sustaining many top predator species. There has been a 36 per cent decline in the 703 grassland vertebrate populations of 149 species studied since 1970. Grasslands are maintained by processes such as artificial and natural fires, grazing, droughts and rainfall. This creates a delicate balance of influences which can be easily disrupted, leading to the acceleration of processes such as desertification.
Source: Table 2: The Living Planet Index, Ecological Footprint, Biocapacity and Water Footprint Through TIme, 1961-2005. in The Living Planet Report 2008. © 2008 World Wildlife Fund for Nature, Gland Switzerland. With contributions from the Zoological Society of London and Global Footprint Network. ISBN: 978-2-88085-292-4. Downloadable from http://www.footprintnetwork.org/en/ind ex.php/GFN/page/living_planet_report/.
Biogeographic Realms
The Earth’s land surface can be divided into
regions or realms characterized by distinct assemblages of
animals and plants. Trends in species populations are different in
each realm according to the intensity and history of the threats to
their biodiversity. The following figures show trends in terrestrial
and
freshwater species populations in each realm.
Species in the Nearctic realm have been extensively monitored, providing a large amount of population trend data. Species population abundance from 1970 to 2005 shows no overall change in 1,117 populations of 588 species.
By contrast, the Neotropical index shows a 76% decline from 1970 to 2004 in 202 populations of 144 species. While this index combines data from all vertebrate classes, the amount of population data available for the Neotropical index is small relative to the other realms. As a consequence, the magnitude of the trend is largely driven by catastrophic declines in a number of amphibian species such as the golden toad (Bufo periglenes) from Costa Rica, which is now thought to be extinct. Decreases in abundance are also apparent in other Neotropical species, but not at such a rapid rate. The Neotropics contain 40 per cent of all plant and animal species on the planet, the most biodiverse of all the biogeographic realms. These species are under threat mainly from habitat loss. For example, between 2000 and 2005 the net loss of forests in South America was about 4.3 million hectares per year, exceeding that of all other regions.
In the Palearctic realm, the average trend in abundance from 1970 to 2005 increased 30% in 552 populations of 363 species. Most of the population data available are from Western Europe, the part of the world most affected by human activities over the past 300 years. More than 50 per cent of the land has been converted for agricultural use, so many species declines are likely to have occurred before 1970. The positive trend for the Palearctic realm since 1970 may, in part, reflect conservation successes resulting from habitat protection, reduction of pollution or other environmental improvements. However, with globalization, pressure on the environment has shifted to the tropics and other regions. Trends in the Eastern Palearctic are less certain as fewer data are available. One species of concern is the saiga antelope (Saiga tatarica), populations of which have plummeted due to hunting pressure over the last 40 years.
The Afrotropical index shows an average decline of 19% over the 35-year period in 552 populations of 201 species. Recent positive trends in the index could reflect some of the conservation efforts on species such as the white rhino (Ceratotherium simum). However, the northern subspecies has been extirpated from most of its historical range and is now on the brink of extinction (see opposite). This shows that although progress is being made towards recovery and protection of certain species in the Afrotropical realm, conservation action in the region is still essential for reducing the rate of decline.
The Indo-Pacific index combines species population data from three realms: Indomalaya, Australasia and Oceania, as there are insufficient data to produce individual realm results. The index reveals an average decline of about 35% from 1970 to 2005 in 441 populations of 155 species, with a constant downward trend since the late 1970s. Tropical forest loss has been most severe in the Indo-Pacific realm, where much of the original forest has been cleared for agriculture or plantations, driven by the international demand for products such as palm oil.
Source: Table 2: The Living Planet Index, Ecological Footprint, Biocapacity and Water Footprint Through TIme, 1961-2005. in The Living Planet Report 2008. © 2008 World Wildlife Fund for Nature, Gland Switzerland. With contributions from the Zoological Society of London and Global Footprint Network. ISBN: 978-2-88085-292-4. Downloadable from http://www.footprintnetwork.org/en/ind ex.php/GFN/page/living_planet_report/.
Birds and Mammals
While broad trends across ecosystems provide an
overview of changes in population numbers, they do not show
the relative impacts of human pressures across different species
and taxonomic groups.
There are almost 10,000 species of bird inhabiting a diverse range of habitats. Their widespread distribution, plus the fact that extensive information has been collected on them, has enabled a robust indicator of bird trends to be produced. The decline of 20% in the bird index (which evaluates 2,185 populations of 895 species) masks a more serious decline of 50% experienced by surveyed populations of tropical and marine birds. Major threats include habitat loss, invasive alien species, overexploitation and pollution.
More than 5,400 mammal species have been described, of which 20 per cent are classified as threatened by the IUCN Red List of Threatened Species. The mammal index has decreased by 19% in the 1,161 surveyed populations of 355 species over the last decade, with the most serious declines in the tropical realms. Overexploitation is one of the principal threats to this group, extensively targeted by the bushmeat trade, notably in Africa and Southeast Asia.
Source: Table 2: The Living Planet Index, Ecological Footprint, Biocapacity and Water Footprint Through TIme, 1961-2005. in The Living Planet Report 2008. © 2008 World Wildlife Fund for Nature, Gland Switzerland. With contributions from the Zoological Society of London and Global Footprint Network. ISBN: 978-2-88085-292-4. Downloadable from http://www.footprintnetwork.org/en/ind ex.php/GFN/page/living_planet_report/.
Other Papers in this Series
- Tipping Points. The notion that the planet's climate has now reached a tipping point, and has begun to change on its own, is conjecture. But there are reasons to think a tipping point has been reached.
- Trends in Biodiversity Overall declines in terrestrial, marine, and freshwater animal populations; declines in tropical forests, dryland systems, and grasslands; declines in Neotropical, Afrotropical, and Indo-Pacific regions; declines in birds and mammals. Last revised Wednesday, January 7, 2009.
- Thawing Permafrost In southern Alaska, the permafrost has gone from 0 days per year above freezing in 1987 to 139 days above freezing in 1993. Last revised Wednesday, January 14, 2009.
- Trends in Atmospheric Carbon Dioxide There has been a geometric growth in atmospheric carbon dioxide since the Industrial Revolution, whether measured through Ice Cores, at Mauna Loa, or at marine sea surface sites. Last revised Wednesday, January 7, 2009.
- Trends in Atmospheric Methane The concentration of methane (CH4), the most abundant organic trace gas in the atmosphere, has increased dramatically over the last few centuries, more than doubling its concentration. Atmospheric methane levels of the past 150 years far higher than those of the previous 420,000 years, and are currently 2.5 times as high as any previous level. Last revised Wednesday, January 7, 2009.
- Trends in Global Temperature: Appendix In this appendix to Trends in Global Temperature, we examine monthly anomalies, seasonal anomalies, and mean global temperature in degrees centigrade. The Northern Hemisphere has generally warmed more than the Southern. This gap emerged in about 1920, disappeared between 1965 and 1990, but has re-emerged. Warming in the Northern Hemisphere has been most severe in the Arctic. Between 1920 and 1960, the Arctic was warmer than normal, and the Antarctic was colder than normal. Since 1980, both Arctic and Antarctic have been warmer than normal, with the greatest warming occurring in the Arctic. Last revised Sunday, January 11, 2009.
- Trends in Global Temperature For the 2000 years prior to 1880, the earth was cooler than it now is, and was cooling. However, a growth curve best describes measured global temperatures since 1880. The ten warmest years on record have occurred in the 12-year period 1997-2008, and the pace of warming may be increasing. While mean temperature is now rising rapidly, seasonal variability appears to be decreasing. Last revised Wednesday, January 14, 2009.
- Trends in Snow and Ice Cover In the Northern Hemisphere, the average snow extent has decreased by 3.75 million square Km in the last 39 years. The greatest loss of snow cover has occurred in the months of June and July. In the Northern Hemisphere, the average extent of sea ice decreased by 1.5 million square Km during the period 1978-2008, from about 9.9 million square Km to about 8.4. In the Southern Hemisphere in this period, the extent of sea ice did not change significantly. Reduced snow and ice cover changes albedo, increasing the rate of warming. Last revised Friday, January 16, 2009.
- "Anthropogenic": A Look at Critical Correlates of Human Population Growth abstract Last revised Wednesday, January 14, 2009.
© 2009 David Stang. All rights reserved. Dr. Stang is available for presentations on this topic. Contact him by email. |
Last Revised: Wednesday, January 7, 2009