Living Planet Index keeps watchful eye on endangered species

As we speak, millions of people up and down the UK are preparing to fill in their household’s form for the 2021 census. Keeping track of numbers such as population is highly valuable.

Just as the census allows people to count the UK’s population, the Living Planet Index (LPI) helps keep a rough tally for the health of various animal populations across the globe. Managed by the Zoological Society of London (ZSL) and the World Wide Fund for Nature (WWF), the index collates data from thousands of species.

As of 2021, the index measures the state of 4,005 species in total, equivalent to 27,549 individual populations of vertebrate animals living on land, in freshwater and marine habitats. Using 1970 as a base-year, starting with a total of one, the index measures an aggregate population size for all the species it monitors.

In the midst of a global pandemic, it is now more important than ever to take unprecedented and coordinated global action to halt and start to reverse the loss of biodiversity and wildlife populations across the globe by the end of the decade, and protect our future health and livelihoods. Our own survival increasingly depends on it.

– Marco Lambertini, Director General, WWF International

On the face of it, the index seems to indicate that we’re heading for disaster – at the latest reading, the index claimed that population sizes for mammals, reptiles, fish, birds and amphibians had fallen by 68 per cent on average.

But all is not as it seems…

Blinded by numbers

A 68 per cent drop sounds catastrophic, but critics of the LPI claim it is too blunt an instrument to accurately depict how each individual animal population is actually changing. If you were to calculate the size of two populations over time, and one population collapsed by 80 per cent while the other remained stable, you would end up with an average drop of 40 per cent.

While the figure masks the dramatic decline of one population, it also misses the overall health of the other. This issue is front and centre of the limitations people believe face the LPI. Sample sizes are another – an article published in the Nature journal suggests the LPI estimates of significant declines in populations are driven by just three per cent of total vertebrate populations.

Stripping out the minority of populations experiencing extreme declines dramatically changes the result, and suggests that global animal populations are actually increasing overall. For example, the humpback whale population is actually increasing in parts of the North Pacific.

Counting a biological budget

While the LPI’s overall population statistic might not necessarily be useful in understanding the species-by-species changes, the 2020 report includes a useful metric which gets to the root of the problem – humans are living beyond their means, and not just in a purely financial sense.

The LPI has devised an Ecological Footprint, something of a biological budget which accounts for a country’s resource consumption, including factors such as importing and exporting products, plus registering the carbon emissions given off in pursuit of these goods and services.

North America, Europe, the Middle East and Oceania are some of the regions busting their biological budgets the most, while countries in Africa and Asia are not far behind, seemingly picking up on the bad habits of wealthier neighbours elsewhere. Misuse of land is one of the leading disruptors of natural biodiversity.

Fortunately, there’s much we can actively do to arrest further disruption. The LPI’s 2020 report concludes, producing a range of scenarios for the future, painting different pictures for how we can flatten the curve and alter our consumption of resources. Less land used for intensive farming, for example, and more conservation of natural forests and green spaces are just some of the things each nation can do, to protect endangered species, wherever they may be.

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