Latest report by the WWF reveals that wildlife populations have declined by an average of 69% since 1970.
Anyone who’s watched a David Attenborough documentary over the last 10 years will be aware that the wildlife on our planet is suffering. Estimating to what extent, however, is a tricky business and while it remains impossible to count every wild animal all the way from worms to whales, a new study published last month gives the most comprehensive figure to date.
The report, known as the Living Planet Index, is a collaboration between the World Wildlife Fund, more commonly known as the WWF, and the Zoological Society of London. Published biennially, the review aims to capture “trends in global biodiversity and the health of our planet” and in this latest edition the headline finding is this: between 1970 and 2018, population abundance of monitored vertebrates has declined by an average of 69%.
If you’re struggling to wrap your head around such a staggering decline, of over two thirds of the earth’s animal population in just 48 years, then you’re not alone. The number is mind-bogglingly large and begs the question: what does a statistic like that really mean for the wildlife on our planet?
Well, firstly it should be noted that this report only covers vertebrates, that is, mammals, birds, reptiles, fish, and amphibians. Typically, these are the creatures that spring to mind when considering ‘wildlife’, but they actually represent the minority of animals on our planet. Animals without a spine are much more numerous and yet scientists have far less data on how their populations are getting on; the numbers we do have, particularly for insects, are not exactly rosy.
“The biggest regional decline was recorded for the populations in South America, down 94% from 1970.”
The second important point is that this finding is for monitored populations. In total, the study tracked nearly 32,000 populations of 5,320 different species using, essentially, all relevant and available published scientific research from the past 50 years. That’s just about as comprehensive a study as we might ever be able to produce but obviously it does not and cannot cover everything.
The consequences of how this study was carried out are therefore twofold:
- The study is designed to show how populations are changing over time, not how many individual animals are born/die. This means the percentage change from each population is taken and then these changes are averaged out to produce a final figure. Some of the populations were likely much larger than others, but this is not taken into account.
- We must accept some bias in the species that were monitored. This isn’t randomised sampling across all of nature, instead, the result reflects what data is available.
At this point it would be fair to wonder whether a few bad apples could be spoiling the bunch. Is it possible that a small number of drastically declining populations are negatively skewing the results?
In short, yes, it is possible, but that’s not what has happened here. The researchers were careful to check for this and found that even when excluding the most drastically changing 10% of the data set, the average decline was still around 65%.
So, now that we’ve established how exactly the data was collected, we can discuss what the result really means.
The biggest regional decline was recorded for the populations in South America, down 94% from 1970. This is not surprising given that the continent also tops the chart for deforestation rates. Africa was next at 66%, followed by Asia and the Pacific, at 55%; North America saw a decline of 20%; Europe and Central Asia was the lowest with an 18% average decline. Unfortunately, the smaller declines seen in North America and Europe are not something to celebrate, these regions likely have less to lose as a result of developments that occurred long before 1970, when the study began. In terms of habitat type, freshwater species populations have seen the greatest overall decline, 83% globally.
But what’s driving this global biodiversity loss?
Humans, of course, although the mechanisms driving the drop are changing. According to the report, the main reason for the collapse in biodiversity over the past 50 years has been our over-exploitation of ecosystems. On land, that’s mostly agriculture and at sea it’s overfishing – providing food to an ever-growing global populous is a challenge but one we know how to tackle more sustainably, albeit with some concerted effort.
Over the next 50 years it’s likely that human land and sea use will be eclipsed by climate change as the primary cause of biodiversity loss. The report painstakingly sets out the difference between a world that’s 1, 2, 3 and 4 ᵒC warmer, with each scenario looking increasingly grim for wildlife and, therefore, us.
“It’s bad; it’s getting worse; it’s not unsalvageable.”
COP27, the UN climate change conference, is taking place just a month before the UN biodiversity conference in Montreal – these are two major opportunities for world leaders to come together and finally provide some solutions to the problems we’ve created for the natural world. The consequences of inaction at these crucial meetings will be grave, we simply cannot afford delay anymore.
Fundamentally, the solutions to both climate change and the unfolding biodiversity crisis are within our grasp and stand to benefit the communities and societies who implement them. As with so many reports and studies on climate change and biodiversity, the take home message from the Living Planet Index is it’s bad; it’s getting worse; it’s not unsalvageable.