The Living Planet Index (LPI) is a tool that shows how global biological diversity is changing over time. It tracks population trends of vertebrate species from around the world. The Zoological Society of London (ZSL) works with the World Wide Fund for Nature (WWF) to manage the index. It is one of the most well-known global tools for measuring changes in biodiversity.

The index was first created in 1997 to develop a way to measure changes in Earth's biodiversity over time. As of 2022, the index is calculated using data from scientific studies, online databases, and government reports. It includes information about 31,821 populations of 5,230 species, including mammals, birds, reptiles, amphibians, and fish.

Results

According to the 2022 report, wildlife populations that are being watched show an average drop of 69% between 1970 and 2018. This suggests that natural ecosystems are becoming worse at a speed never seen before in human history. Many trends match larger global studies that say losing biodiversity is one of the biggest environmental problems affecting ecosystems worldwide. The amount of decline varies by region, with vertebrate populations in Latin America and the Caribbean dropping by an average of 94%. A major cause of these drops is changes in how land is used, such as farming or logging, which can destroy or harm habitats. Other problems, like climate change, pollution, and overuse of wildlife, can make these drops worse.

The 2024 report showed an average decline of 73% between 1970 and 2020.

The Living Planet Database (LPD) has been online since 2013 and has been kept up to date by ZSL since 2016. The LPD includes more than 30,000 population trends for over 5,200 species of fish, amphibians, reptiles, birds, and mammals.

The global Living Planet Index (LPI) is calculated using population data collected from many sources, such as scientific journals, online databases, and government reports. The index focuses on vertebrate species because long-term data for invertebrates and plants are less common.

A special method called generalized additive modeling is used to find trends in each population's data. Average changes are calculated and grouped by species. Recent improvements aim to make the index more accurate by considering uneven data availability across regions and species.

Each species trend is grouped to create an index for land, ocean, and freshwater ecosystems. This process uses a weighted geometric mean method, which gives more weight to groups with more species in each area. This helps balance uneven data in the LPD. The three system indexes are then averaged to create the global LPI. Despite these changes, challenges remain in making sure the index accurately shows biodiversity patterns in areas with less data.

Ongoing work on the index focuses on increasing data coverage and reducing bias across species and regions.

Most of the data used in the index is specific to certain species or regions. This means the index has gaps and biases in taxonomy, geography, and time. Because of this, researchers say the index should be used carefully when showing global biodiversity trends.

It has been noted that the index treats all population drops the same, even if they are not close to extinction.

In 2005, WWF authors found that the data might not represent all areas accurately. By 2009, the database was found to have too much bird data and missing information about tropical species, though it showed "little evidence of bias toward threatened species." The 2016 report was criticized for focusing too much on western Europe, where more data was available. A professor at Duke University said combining data from different regions and ecosystems into one number might be misleading and aimed at drawing attention or raising money. Later studies showed that differences in data availability across regions can affect how large the reported declines seem.

A 2017 study by ZSL members found larger declines than previously estimated and suggested that areas with less data might have faster declines.

In 2020, a re-analysis by McGill University showed that the overall 60% decline since 1970 was mainly due to less than 3% of the studied populations. When extreme declines were removed, the decline still existed but was less severe. When more extreme cases were removed, the trend changed to show a decline between the 1980s and 2000s, but a slight increase after 2000. This shows the index is very sensitive to extreme changes, raising concerns about its accuracy.

A 2021 study found that the index did not account for random population changes, leading to incorrect results even when populations were stable. This shows that how the index is built can greatly affect how trends are seen.

A 2022 study said the index is not a good measure of how many animals there are. This has led to debates about whether the index shows real changes in numbers or just relative trends in data.

A 2024 study by Charles University found that the index had math problems that made it overestimate declines in vertebrates. When these issues were fixed, most vertebrate populations showed balanced declines and growth, except amphibians, which continued to decline steadily.

Publication

The index was first created in 1997 by the World Wide Fund for Nature (WWF) with help from the World Conservation Monitoring Centre (UNEP-WCMC), which is part of the United Nations Environment Programme and focuses on studying biodiversity and creating policies. WWF shared the first results of the index in 1998. Since 2006, the Zoological Society of London (ZSL) has worked with WWF to manage the index.

Findings from the index are shared every two years in the WWF Living Planet Report and in other reports, such as the Millennium Ecosystem Assessment and the UN Global Biodiversity Outlook. Now, reports are also being made for specific countries and regions to address local issues. The most recent Living Planet Report was published in October 2022.

Coverage

The WWF used the index as a useful tool to raise public and political attention on biodiversity loss and conservation by sharing a clear message. This simple way of communicating helped the index become commonly used in public and policy discussions, though it can sometimes cause misunderstandings about what the data mean.

The index is often wrongly reported in the media, with incorrect claims that it shows a 69% loss of all animals or species since 1970. This widespread misunderstanding has led to many articles being written to explain what the LPI does and does not show, and how to correctly understand the trends. Explaining how to correctly interpret the index has become an important topic in recent scientific and public discussions.

Convention on Biological Diversity

The index has helped governments make important decisions and check how well countries are meeting goals set during international agreements. It is often used to measure progress toward protecting biodiversity and to guide efforts to save wildlife and ecosystems.

In April 2002 and again in 2006, during the Convention on Biological Diversity (CBD), 188 countries agreed to take action to "… greatly reduce the loss of biodiversity worldwide, regionally, and nationally by 2010."

The Living Planet Index (LPI) was important in showing how well countries met the CBD's 2010 goal. It has also been chosen by the CBD as a way to track progress on three targets from the Nagoya Protocol (2011–2020), which are part of the Aichi Biodiversity Targets. Because of this, the index has become a key tool for monitoring global efforts to protect biodiversity over time.

To support the CBD's 2020 plan, the Indicators and Assessments Unit at ZSL works to use the best methods for measuring changes in wildlife populations. They also aim to expand the LPI to better represent all types of biodiversity and break down the index into parts that show changes in species that are hunted or have spread to new areas.