In the quiet alpine meadows, insects are disappearing—Signs of collapse progress even in "untouched" areas

"There is no longer a 'safe zone'—a warning bell from the highland grasslands"

"Nature untouched by human hands is the last stronghold." This common belief has been contradicted by recent findings. Associate Professor Keith Sockman from the University of North Carolina recorded the number of flying insects over 20 years in the subalpine grasslands of Colorado. The results revealed a shocking trend: an average annual decline of 6.6%, accumulating to a total decrease of 72.4%. The survey site was a protected natural environment with minimal direct human pressure. Yet, the numbers declined—why? The key was the rise in summer temperatures.Phys.org

Research Details: 15 Seasons, 20 Years, One Grassland

The survey was conducted over 15 seasons between 2004 and 2024. Using traps and standardized methods, the relative abundance of flying insects was measured each season. The analysis compared 38 years of weather data and 59 combinations of weather factors using information criteria. The conclusion was clear—the hotter the previous summer, the fewer insects in the following season. The rise in minimum daily temperatures was particularly significant, increasing at a rate of about 0.8°C per decade.PubMed

Such "continuous observations at a single site" offer high data accuracy and consistency, but caution is needed for spatial generalization. However, the results from this grassland are not isolated exceptions. In 2023, another report from a different subalpine grassland in Colorado indicated a 62% decrease in insect numbers and a 47% decrease in biomass over 35 years from 1986 to 2020. Insects are uniformly declining even in seemingly untouched highland areas.The Colorado SunESA Journals

Why are numbers declining even in "untouched nature"?

The study cites climate—particularly summer warming—as a major factor behind the continued decline in areas with minimal human impact, such as pesticides and habitat destruction. High temperatures increase mortality rates of adults and larvae, disrupt developmental cycles and breeding timings, and create mismatches with food resources (nectar, leaves, other insects). The rise in minimum temperatures affects nighttime rest and metabolism, potentially causing chronic stress. When these factors combine, it becomes difficult for populations to recover in the following season. Broad meta-analyses estimate that terrestrial insects are declining at a rate of mid-single digits per decade, but the figures from this mountainous region are even more severe.PubMedWikipedia

When "half of the tree of life" withers

Insects are the "invisible pillars" of terrestrial ecosystems. They play roles in pollination, decomposition, soil formation, and serve as a food base for birds, bats, and amphibians. Even in protected nature reserves, insects are declining, and there are increasing reports of forests feeling "silent." In Costa Rica's reserves, moths attracted to light have drastically decreased from the "cloud-like" densities of decades ago to just a few individuals. This is not a solitary tale of woe but a global signal.The Guardian

The spreading sense of crisis on social media and the reality on the ground

When this study was reported, it spread on social media as a "canary in the coal mine" for ecosystem collapse. Ornithologist Gary Ritchison pointed out on X that "the widespread decline of insects casts a dark shadow on the future of their ecosystems," expressing concern that declines in protected areas could lead to the weakening of entire predator and pollination networks.X (formerly Twitter)

On Reddit, threads about long-term research in Colorado highlighted "the importance of this study is that declines are occurring even in areas with little human impact" and suggested that "climate change might be the main cause." Community boards in the region frequently feature threads discussing the feeling of "no insects" in summer gardens. Beyond scientific rigor, the lived experiences of people are beginning to align with the data.Reddit

What's at stake: Pollination, agriculture and food, water and soil

The decline in insects is not the type of crisis that will immediately empty supermarket shelves. However, the degradation of pollination services will affect the yield and quality of fruit and vegetables, and the decline of natural pest enemies will lead to a vicious cycle of increased pesticide use. A decrease in decomposers disrupts the carbon cycle in the soil, and a thinning insect network in the mountains leads to a decline in birds and amphibians adapted to highland ecosystems. The IPCC has noted that as global warming progresses, the high extinction risk for invertebrates, including insects, spreads. What happens in the mountains will have repercussions for agriculture and urban life in the lowlands.Wikipedia

Strengths, limitations, and reproducibility of the study

The strengths of this study include (1) continuous observation over 20 years, (2) integration with detailed weather data, and (3) the contrasting nature of a site close to "unmodified." However, (a) the site is singular, (b) results may be influenced by trap sensitivity and community seasonality, and (c) estimating contributions from factors other than temperature (precipitation, snow, extreme events) requires future multi-site comparisons. Fortunately, the paper has made its data and analysis code publicly available, ensuring verifiability. As layers of replication studies grow, regional differences and commonalities should become apparent.PubMedfigshare.com

What we can do: From policy to the garden

• Accelerate the reduction of greenhouse gases: Energy transitions at city, state, and national levels are the only means to slow down the climate across wide areas, including mountains.

• Enhance the "quality" of protected areas: By expanding core areas and ensuring connectivity, we can leave "paths" for movement and re-establishment. If reserves become "islands," resilience decreases.The Guardian

• Biodiversity-conscious agriculture and urban planning: Reducing pesticide use, shielding nighttime lighting, and planting native vegetation are steps to repair pollination networks and urban insect pathways.

• Citizen science monitoring networks: Even sharing simple traps or observation records set up in gardens or schools can fill spatial data gaps.

Conclusion: Visualizing the invisible "silence"

This report confronts us with the inconvenient truth that insects are declining even in protected areas. Mountains are quick to show the impacts of climate change, serving as a "microcosm of the future." The data from the silent grasslands urge us to take two actions. One is to accelerate emission reductions and adaptation measures. The other is to continue "measuring" the less visible changes. To bring back the hum of insects to the quiet grasslands.Phys.orgPubMed

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