While many researchers assert that our planet is undergoing a new mass extinction event, a recent study challenges this notion by reevaluating extinction data from the past 500 years. The study, conducted by Kristen Saban and John Wiens of the University of Arizona, suggests that extinction rates have actually decreased over the last century.
The research, published in the Proceedings of the Royal Society of London, is unique in its in-depth analysis of extinction patterns among plants, arthropods, and vertebrates. The findings indicate that extinction rates peaked approximately 100 years ago and have since declined, contradicting the idea of accelerating extinction rates.
Wiens, a professor of ecology and evolutionary biology, pointed out the flawed assumption that past extinction patterns can be projected into the future. “We discovered that the causes of those recent extinctions were very different from the threats species are currently facing,” he explained, highlighting the role of habitat loss and climate change as current threats.
The study analyzed data for nearly 2 million species and found that past extinctions were primarily driven by invasive species on islands, such as the Hawaiian Islands. In contrast, today’s most significant threat is habitat destruction, especially on continents where most extinctions now occur in freshwater habitats.
“To our surprise, past extinctions are weak and unreliable predictors of the current risk that any given group of animals or plants is facing,” said Saban, the study’s lead author. Saban, who is now a doctoral student at Harvard University, emphasized the importance of understanding present threats for more accurate future predictions.
The researchers also explored threat levels as defined by the International Union for Conservation of Nature, assessing 163,000 species. They found that while past extinctions involved island species like mollusks and vertebrates, current threats primarily affect mainland species vulnerable to habitat loss.
Although climate change remains a significant concern, the study did not find evidence linking it to increased extinction rates over the past 200 years. “That does not mean that climate change is not a threat,” Wiens clarified. “It just means that past extinctions do not reflect current and future threats.”
Some groups, such as arthropods and plants, have experienced a decline in extinction rates since the early 1900s. Wiens attributes this trend to successful conservation efforts. “Many people are working hard to keep species from going extinct. And we have evidence from other studies that investing money in conservation actually works,” he noted.
Saban expressed hope that the study would foster a more nuanced discussion of biodiversity loss. “By looking at the data in this way, we hope that our study helps inform our overall understanding of biodiversity loss and how we can come up with better ways to address it,” she said.
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