In today’s German nature reserves, insect traps capture significantly fewer insects compared to 1989. Entomologists in the Krefeld area have consistently monitored this over 27 years, revealing a decline in flying insect biomass exceeding 75 percent even in protected areas, where ecosystems are expected to be preserved.
Since the start of this century, two concerning declines have occurred simultaneously: a noticeable reduction in vertebrate life, including mammals, birds, fish, amphibians, and reptiles, and a less apparent but more extensive decrease in insects, which are crucial to nearly all ecosystems. Data tracking biodiversity loss dates back to 1970. However, it is the detailed measurements from long-term studies that started after 2000 that have turned isolated concerns into a well-documented trend, highlighting the losses that have occurred during our watch and their implications for future generations.
The Vertebrate Ledger
The World Wildlife Foundation and the Zoological Society of London’s 2024 Living Planet Report indicates that between 1970 and 2020, the average population of 5,495 monitored vertebrate species decreased by 73 percent. It is crucial to understand this correctly: it does not imply that three-quarters of all animals have disappeared. Instead, it means that, on average, monitored populations declined by 73 percent, with approximately half decreasing while the rest remained stable or grew. The average is heavily influenced by significant declines, such as an 85 percent drop in freshwater animal populations and a 95 percent decline in wildlife in Latin America and the Caribbean.
The decline is uneven across regions. In North America, a 2019 study published in Science reported a net loss of nearly 3 billion breeding birds since 1970, about one in four, spanning 529 species, including some common backyard birds previously considered safe.
Amphibians face the most severe challenges among vertebrates. The second Global Amphibian Assessment from 2023 states that 41 percent of amphibian species are at risk of extinction, with climate change contributing to 39 percent of the documented declines since 2004.
Some losses are now irreversible at the genus level. A 2023 paper by Gerardo Ceballos and Paul Ehrlich reported the extinction of 73 entire vertebrate genera since 1500, a rate they argue surpasses the historical background rate over the past million years. The IUCN Red List, which is the most comprehensive inventory available, currently lists over 47,000 species as threatened out of more than 169,000 assessed.
The Insect Crash Almost No One Sees
While vertebrates, often seen as endearing, are mourned, insects, which are vital yet less visible, face a decline that is harder to track due to the scarcity of long-term studies. However, the Krefeld study revealed in 2017 a more than 75 percent reduction in insect biomass that could not be attributed to local factors like weather or land use, indicating a systemic issue.
A 2020 meta-analysis in Science, which analyzed 166 long-term datasets, confirmed a global decline of terrestrial insects at roughly 9 percent per decade. Conversely, it also identified some regions where freshwater insects were recovering, likely due to efforts to clean polluted water bodies. This variability suggests that local actions can significantly impact biodiversity, indicating that while the decline is not uniform, human intervention can alter its trajectory.
The declines in vertebrates and insects are interconnected crises. Insects form the base of the terrestrial food web, impacting the bird populations in North America, many of which are insectivores that faced food shortages. When the biomass at the base of the food chain diminishes, the species that rely on it are affected.
Insects also perform essential ecological services that bolster the economy. The IPBES global pollinator assessment indicates that about 75 percent of the leading global food crops are partially reliant on animal pollination. Out of 115 key crops, 87, including apples, coffee, and cocoa, depend on healthy insect populations for pollination. Insects are also crucial for waste decomposition, pest control, and soil formation.
These services are currently not priced by any human system, and there is no known scalable replacement. Although the idea of robotic pollinators is appealing, it is far from a comprehensive solution. Current machines can only operate in controlled environments for self-pollinating crops. Arugga’s ground robots and Polybee’s drones can enhance greenhouse yields by 5 to 20 percent, fulfilling roles that could otherwise be managed by handheld tools or captive bees indoors.
Meanwhile, Harvard’s RoboBee, which has been under development since 2013, achieved reliable landing in 2025 but still requires an external tether for power and lacks its own sensors or brain. There is currently no technology that can pollinate an almond orchard or squash field as a wild bee does, naturally and efficiently, while also reproducing itself. Though useful for high-value crops within controlled environments, these robots cannot replace the ecological roles of insects that are rapidly declining.
What the Next Generation Inherits
This ongoing loss significantly impacts the future, a theme this series frequently revisits.
Children born today will experience a diminished natural world with fewer birds, insects, and fish. While this loss is visible, the more profound loss lies in species that disappear before being documented, taking with them potential medical, agricultural, or material innovations that remain undiscovered because the organisms were never studied.
Extinction represents an irreversible environmental damage. Unlike a polluted river that can be cleaned or an atmosphere that might be cooled over time, once a lineage ends, it cannot be revived. The biodiversity declines observed in the past 25 years represent some of the most permanent losses we are recording.
Nonetheless, there is still hope. Half of the monitored vertebrate populations remain stable or are increasing. North American raptors and waterfowl have rebounded following targeted conservation efforts and chemical bans. Freshwater insects have shown recovery where water quality has improved. While the losses are significant and primarily caused by human activities, this also means that human decisions still have the power to change the course of biodiversity.
What You Can Do
- Create an insect-friendly area. Plant native species, avoid pesticides, and leave leaf litter through winter to support pollinators and the ecosystem, even in small spaces like balcony planters.
- Reduce light pollution. Use shielded, warm-toned outdoor lights on timers to alleviate stress on nocturnal insects.
- Support long-term monitoring. Participate in community science projects such as bird counts and butterfly surveys to contribute essential data that sheds light on these declines.
- Advocate for large-scale changes. While individual efforts help, advocating for pesticide regulations, habitat corridors, and protected area funding can drive change on a broader scale.
- Reduce land pressure through diet. Since agricultural expansion is a major driver of biodiversity loss, reducing food waste and choosing low-impact consumption can help mitigate it.
