One of the largest conservation organizations on the planet, WWF (WWF ), recently released a shocking statistics: over the past half century, the number of most major animal groups, including mammals, birds and fish, has dropped by an average of 69%. WWF and another nonprofit, London Zoological Society (ZSL), calculated these amazing numbers using an indicator called the Earth's Vitality Index (LPI). The index is designed to measure how animal populations generally change over time. Rebecca Shaw, chief scientist at WWF, said their idea is that this number can provide early warning that the ecosystem is at risk.
▲The trend of the earth's vitality index.
50 declined by nearly 70%
According to the biennial World Fund for Nature and the London Society of Zoology, the number of birds, fish, amphibians, and reptiles, plummeted, from the high seas to the rainforests, reducing by more than two-thirds from the average between 1970 and 2018. Two years ago, the figure was 68%, and four years ago, it was 60%.
is even worse for animals in certain habitats and regions. Freshwater species communities, such as fish and frogs, have decreased by an average of 83% worldwide, while the average number of wildlife in Latin America and Caribbean (including the Amazon) has dropped the most, down 94% in 48 years. Tanya Steele, CEO of the UK chapter of WWF UK, said: "This report tells us that the Latin American region has the worst forest degradation, which has the largest tropical rainforest in the world - the Amazon rainforest. The deforestation rate there is accelerating, not only depriving trees (the right to grow) from this unique ecosystem, but also depriving wild animals (the right to survive) from trees, and depriving Amazons of their ability to be one of our greatest allies in fighting climate change."
▲Freshwater biochange index.
Africa ranked second with a 66% decline, followed by Asia Pacific (55%) and North America (20%). Europe and Central Asia fell by 18%. The report said that the total loss is equivalent to the disappearance of the population in Europe, the Americas, Africa, Oceania, and China.
Steele said: "Despite scientific research, catastrophic predictions, passionate speeches and commitments, burning forests, submerged countries, record temperatures and millions of displacement, world leaders continue to stand by and watch our world burn before our eyes."
" Earth Vitality Index " combines a global analysis of 5,230 animals in 32,000 populations to measure changes in wildlife populations across continents and taxa, producing a chart similar to the Earth's Life Stock Index. According to this report, land use change remains the most important driver of global biodiversity loss. "Global, the main decline we are seeing is the loss and fragmentation of habitat caused by global agricultural systems," said Mike Barrett, executive director of science and conservation at the UK chapter of the WWF UK. The researchers stressed that it is becoming increasingly difficult for animals to move on land due to obstacles from infrastructure and farmland. Among rivers with a length of more than 1,000 kilometers, only 37% of the rivers remain free to flow throughout the entire journey, while only 10% of the world's land reserves are connected. Researchers say future declines are not inevitable. They listed the Himalayas, the East Coast of Australia, the Albertin Rift Valley, and the East Arc Mountains in eastern Africa, as well as the Amazon Basin as priority conservation areas.
▲Amazon Rainforest.
WWF Africa Regional Director Alice Ruhweza said the assessment shows that when nature disappears, “the cost of human beings is huge.” She said young people are particularly concerned about wildlife protection and will promote the government to implement greater protection measures."We have a young, entrepreneurial, and ever-increasing education population, and they show more awareness of natural problems," she said. "So the potential for change is huge. But time is not long, and we need to act now." What is the Earth's vitality index? The day of an ecologist usually involves several animals. They counted the bugs on the car windshield , used drones to fly over the water bird flock, tied camouflage cameras on the trees, and took photos when animals walked by. Over time, these numbers reveal changes in wildlife populations. For example, if a group of florida manatee exhausted food in a certain year, subsequent surveys may find their number decreases, thus showing a decrease in quantity, usually expressed as negative percentages. ▲The staff are rescuing marine life.
"Earth Vitality Index" is based on all these statistics. To derive the global LPI, scientists first calculated the changes in individual populations of birds, mammals, reptiles, amphibians and fish between 1970 and 2018 (the data always lags a few years). For example, the number of 1,000 manatees has decreased by 500, a 50% reduction. The same happened in a country with 10 people, and the population of this country has only decreased by 5 people. Then they average all the changes, whether they increase or decrease, and they get a number. This means that the index is the average of population size changes, not the average of lost organisms.
Let's go back to the title number of the WWF report: 69%. This figure shows that if you averaged the changes in wildlife populations around the world since 1970, you would get a 69% reduction. This number is generally helpful. It helps us understand that many animals are declining. However, this number does not mean that the number of animals today is two-thirds less than 50 years ago. Again, it does not calculate the number of animals lost in each group and add them together, it measures the relative decline scale of each population and takes its average. It is this distinction that is confusing and most often misunderstood. "(LPI) is continually interpreted as we have lost 69% of the world's animal resources," said Brian Leung, associate professor of ecology at McGill University. "
"It's easy to think that the population of these wild animals has dropped by 69% on average, but it's not the case." This year's addendum to the report provides an example of this misunderstanding. Imagine, for example, we start with three populations: birds, bears and sharks, the study wrote. The number of birds dropped from 25 to 5, down 80%. The number of bears dropped from 50 to 45, a 10% drop. The number of sharks decreased from 20 to 8, which is 60%. This means an average drop of 50%. But the total number of animals dropped from 150 to 92, down only about 39%. WWF tried to avoid misleading news headlines, explaining in its report that a 69% drop does not mean that 69% of individual animals have disappeared. A large amount of other information is also shown in the report, including other metrics that are often overlooked. Xiao said of LPI: "But we can't really control the interpretation of the media."
So, is the situation still bad? Yes. Some scientists believe that the report actually underestimates the global biodiversity crisis, partly because the devastating decline in amphibian populations may not be fully reflected in the data. And, over time, this trend has not changed. Henrique M. Pereira, professor of conservation biology at the German Center for Integrated Biodiversity Research, was not involved in writing this year's report, saying: "Year after year, despite major policies, we can't start to improve this situation." "We can slow down to some extent at best."
Many scientists believe that we are experiencing the sixth mass extinction - the largest loss of life on Earth since the age of dinosaurs - it is driven by humans.The 89 authors of the report are urging world leaders to reach an ambitious agreement at the COP15 biodiversity summit held in Canada in December this year and cut carbon emissions, keeping global warming below 1.5 degrees Celsius over the decade to stop wanton destruction of nature.
No metric is perfect
In recent years, scientists have pointed out other disadvantages of LPI, such as extreme outliers—that is, a significant decline in wildlife populations since 1970—which may pull down the overall average. Brian's research shows that if these outliers are removed, the overall trend in global LPI is less dramatic. Other studies point out that some statistical methods used to calculate LPI also seem to tend toward a negative trend.
"Think about what LPI is trying to do: summarizing the loss of global biodiversity with a number." Hannah Ritchie, director of research at Our World In Data, said it was not easy. As she told Vox, there are some important warnings for any measure. "That's why scientists I've spoken to tend to point their criticism to the idea of generalizing biodiversity loss, rather than LPI itself."
"There is no perfect indicator." said Falko Buschke, an ecologist and freedom researcher. He led a study last year examining how random fluctuations in animal populations affect LPI. He added that the title data are useful for publicity, but from a scientific point of view, they are often confusing and raise more problems than they solve.
"It's a lofty effort, but it's also a tough effort," Andrew Rypel, a fish ecologist and professor at the University of California Davis, said of large summary statistics. "You want accurate numbers, but you also try to extract a lot of complex data." Another challenge, he said, is that there is no data for a large number of species, including those living in freshwater.
This may sound a bit contradictory. Why do we still make a fuss about how to measure the loss of biodiversity when any measure is bad news? Vox said the measure is important in a race to reverse the decline in wildlife populations. They help determine how government officials, scientists and environmental advocates allocate limited conservation budgets. They can also inform public policy. For example, researchers used LPI to measure progress in several biodiversity conservation goals under a major convention of .
At the same time, policy makers can also mine some good news from this data. Headline numbers like the Global LPI often obscures the fact that the number of plants and animals is changing in very different ways. Overall, these changes are negative and represent a recession—there is evidence that readers are more concerned about bad news. But the population of many wildlife is stable, even increasing. In fact, half of the vertebrate populations in the report showed a growing trend. WWF clearly pointed out this in its report. The group wrote that from 1999 to 2015, in the Crissochu Bay of Cyprus, the number of red turtle nests increased by 500%. This is thanks to intentional conservation activities, and the report also shows that the number of mountain gorillas in the Central African Virunga Mountains has grown from 480 in 2010 to more than 600 today - a large part of this thanks to protection. There are hundreds of examples like this, and these are important stories worth telling. People are tired of seeing negative data that hasn't changed much in the past decade. "I feel people are silent when they receive new information like this," Xiao said. These data show what works: wildlife populations can be restored, and decades of conservation efforts are not nothing.
▲Scientists observe animals.
News source: ABC, VOX, New York Times, Guardian, pictures are from the Internet
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