It’s clear that wildlife on Earth suffers a great deal, but scientists don’t know the exact amount. Determining a comprehensive figure is very difficult. From gnats to whales, counting wildlife on land and in the sea is no easy task. Most countries do not have national surveillance systems.
One of the most ambitious efforts to fill this void is to be published every two years.known as living planet index, it is a joint effort between two major conservation organizations, the World Wide Fund for Nature, popularly known as WWF, and the Zoological Society of London. But the report repeatedly yielded inaccurate headlines when journalists misinterpreted or exaggerated the results.
The latest figures in the rating, released Wednesday by 89 authors from around the world, are the most alarming yet. Between 1970 and 2018, monitored vertebrate populations declined by an average of 69%. More than two-thirds in just 48 years. This is a staggering figure with serious implications, especially as countries prepare to meet in Montreal this December to agree on a new global plan to protect biodiversity. But does that mean what you think?
what the data means and what it doesn’t mean
Remember that this number is only for vertebrates such as mammals, birds, reptiles, amphibians and fish. Spinless creatures, which make up the majority of animal species, do not exist (scientists have even less data on them).
So have wild vertebrates plummeted by 69% since 1970?
No.
This study tracks selected populations of 5,320 species, sucks up all relevant published studies that exist, and adds new data every year as it permits. For example, populations of whale sharks in the Gulf of Mexico are counted from small planes flying low over the water, and birds are tallied by cliff nest numbers. For some species, tools such as camera traps and evidence such as trail droppings help scientists estimate population numbers at specific locations.
This year’s update includes approximately 32,000 such populations.
It’s tempting to think that the average 69% decline in these populations means that the wildlife being monitored has gone extinct. But it’s not. An addendum to the report provides an example of why.
Imagine the authors starting with three populations: birds, bears, and sharks. Birds are reduced from her 25 to 5, an 80% reduction. 50 bears, or 10 percent down to 45. And the shark is reduced from 20 to 8, which is 60%.
This results in an average reduction of 50%. However, the total number of animals decreased from 150 to 92, a reduction of approximately 39%.
The index is designed as such because it seeks to understand how populations are changing over time. It does not measure the number of individuals present.
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“The Living Planet Index is a modern view of human health that supports the natural functioning of the entire planet,” said Rebecca Shaw, WWF Chief Scientist and author of the report.
Another important factor is how the monitored population is ultimately included in the index. They do not represent a broad, randomized sampling. Rather, it reflects the available data. Therefore, it is very likely that there is some bias in which species are being tracked.
One of the controversies is whether the dramatically declining minority population casts doubt on the overall results. Two years ago, a study published in Nature found that just 3% of the population was causing dramatic declines. Once they were removed, the global trend turned to increase.
The paper made a splash in Nature and provided additional clarification and stress testing for this year’s update. On the bright side, the authors note that about half of the population in the Living Planet Index is stable or increasing. However, the average decline remained steep when we tried to exclude the populations showing the most dramatic changes in both directions.
“Even after removing 10% of the full data set, we still see a reduction of about 65%,” said Robin Freeman, head of the Index and Evaluation Division at the Zoological Society of London and author of the report. increase.
yes. Some scientists believe the report actually underestimates the global biodiversity crisis, as the data may have underestimated the catastrophic decline of amphibians. increase.
And over time, the trend does not turn around.
“Despite major policies, year after year the situation cannot begin to improve,” said Henrique M. Pereira, professor of conservation biology at the German Center for Integrated Biodiversity Research, who was not involved in this year’s report. said. “At best, we’ve only slowed the decline.”
Latin America and the Caribbean had the worst regional decline, with a 94% decline since 1970. This pattern was most pronounced in freshwater fish, reptiles and amphibians. Africa was next for him with 66%. Asia and Pacific was 55%. Regions defined as Europe and Central Asia showed a smaller decrease at 18%, as did North America at 20%. The scientists stress that biodiversity loss in these two regions likely occurred long before 1970 and is not reflected in the data.
Scientists know what is causing biodiversity loss. On land, agriculture is the biggest driver, as people turn forests and other ecosystems into farmland for cattle and palm oil. At sea, it’s fishing. There are ways to do both more sustainably.
If climate change does not remain below 2 degrees Celsius, preferably 1.5 degrees Celsius, its impacts are expected to be the main cause of biodiversity loss in the coming decades, says the report.
In December, the nations of the world will come together to reach a new agreement to protect the planet’s biodiversity. The last one almost fell short of its target. The Living His Planet report provides evidence of this success, Dr. Shaw said. A key lesson is that conservation does not work without community support.
“When we have really intensive conservation efforts that involve the community, and the community benefits and manages the results, we see that population growth is possible,” she said. That’s the real bright spot.”