How a Global Experiment is Revealing Earth's Vital Signs
Explore the StoryImagine Earth as a gigantic living organism, with forests acting as its lungs, oceans as its circulatory system, and atmosphere as a protective shield. Now imagine this complex system showing increasingly worrisome symptoms—rising fevers, struggling immune response, and circulation problems 2 .
1.60°C
Above pre-industrial levels in 2024 2
68%
Average decline in wildlife populations since 1970 2
1.3B
Tons of food wasted annually 2
The data is unmistakable: 2024 was confirmed as the hottest year in recorded history, with the global average temperature reaching 1.60°C above pre-industrial levels 2 .
This isn't just about uncomfortable summer heat; it represents a fundamental shift in our climate system with far-reaching consequences. The burning of coal, oil, and natural gas releases greenhouse gases that trap heat in our atmosphere 2 .
The planet has crossed several potential tipping points—thresholds that once crossed can trigger irreversible changes 2 .
While climate change grabs headlines, an equally concerning crisis is unfolding in the natural world: the rapid loss of plant and animal species.
A 2020 World Wildlife Fund report found that population sizes of mammals, birds, fish, reptiles, and amphibians have experienced an average decline of 68% between 1970 and 2016 2 .
The primary driver of this biological devastation is habitat destruction—the conversion of forests, grasslands, and wetlands into agricultural systems and urban areas 2 .
Every hour, forests the size of 300 football fields are cut down 2 .
The world has produced increasingly vast quantities of plastic, much of which ends up in our oceans. By 2040, researchers project the cumulative amount of plastic in the ocean could reach 600 million tons if no action is taken 2 .
The World Health Organization estimates that 4.2 to 7 million people die from air pollution worldwide every year, with nine out of ten people breathing air that contains high levels of pollutants 2 .
Approximately one-third of all food intended for human consumption—around 1.3 billion tons—is wasted or lost annually. This waste accounts for about one-quarter of all greenhouse gas emissions 2 .
| Environmental Challenge | Key Statistic | Primary Impacts |
|---|---|---|
| Global Warming | 2024: 1.60°C above pre-industrial levels 2 | Extreme weather, sea level rise, ecosystem disruption |
| Biodiversity Loss | 68% average decline in wildlife populations since 1970 2 | Ecosystem collapse, reduced resilience, loss of genetic diversity |
| Plastic Pollution | 14 million tons enter oceans yearly; could reach 29 million by 2040 2 | Marine life harm, microplastic contamination, chemical leaching |
| Air Pollution | 4.2-7 million premature deaths annually 2 | Respiratory disease, reduced life expectancy, agricultural damage |
| Food Waste | 1.3 billion tons wasted annually; represents ¼ of GHG emissions 2 | Resource waste, hunger perpetuation, climate impact |
In 2016, a friendly competition between Los Angeles and San Francisco sparked what would become a global scientific phenomenon. The City Nature Challenge (CNC) has since grown into an international community science event that mobilizes people around the world to document biodiversity in their urban environments 5 .
Participants find wild plants, animals, and fungi in their cities and document them using smartphones equipped with the iNaturalist app 5 .
The global community works together to identify the species captured in the uploaded images 5 .
The process is designed for accessibility: find wildlife, take photographs noting the location, and share observations through iNaturalist or a city's chosen platform. The only important rule is that documented organisms must be wild—not planted, cared for by people, or captive in zoos 7 .
Over its ten-year history, the CNC has generated more than 12 million observations of over 113,320 species, creating an unprecedented dataset for studying urban biodiversity 7 .
The data collected through the City Nature Challenge provides real-time insights into urban ecosystems and how they're changing.
Observations included more than 3,338 rare, endangered, or threatened species, such as the Hemphill's Westernslug and the San Clemente Island Fox 7 .
Researchers noted shifts in species distribution and behavior potentially linked to climate patterns. For example, Southern California's unusually dry conditions led to fewer sightings of mating alligator lizards 7 .
The project has revealed how wildlife adapts to city environments, from raccoons navigating suburban fences to millipede clusters in park areas 7 .
The value of the City Nature Challenge extends far beyond a single weekend of nature observation. Once verified, these observations become Research Grade and contribute to the Global Biodiversity Information Facility (GBIF), an international database used by researchers, conservation organizations, and policymakers worldwide 7 .
This massive data collection helps scientists answer critical questions: How are species distributions shifting with climate change? Which areas serve as biodiversity refuges in urban settings? How do different management practices affect wildlife populations?
The project represents a powerful example of democratized science, where everyone can contribute to building knowledge about and protecting the natural world 5 7 .
Environmental monitoring relies on a diverse array of tools and approaches, from sophisticated laboratory equipment to simple observation techniques.
Primary Function: Platform for recording and sharing biodiversity observations
Application Example: Community scientists upload photos with location data during City Nature Challenge 5
Primary Function: Mapping and analyzing geographical data
Application Example: Tracking deforestation rates or mapping species distributions 2
Primary Function: Satellite-based Earth observation
Application Example: Monitoring polar ice melt, forest cover changes, and urban expansion 2
Primary Function: Measuring chemical parameters in water bodies
Application Example: Community groups monitoring local stream health
Primary Function: Automated wildlife photography
Application Example: Documenting elusive or nocturnal species in urban parks
Primary Function: Species identification through genetic analysis
Application Example: Verifying species identifications or discovering cryptic species
The tools of environmental science continue to evolve, with technological advances making it increasingly possible to gather high-quality data at larger scales than ever before. Smartphone technology has been particularly transformative, putting powerful data collection capabilities directly into the hands of millions of potential community scientists 5 7 .
The challenges facing nature are undeniably significant—from a rapidly warming climate to staggering declines in biodiversity. Yet the tools for understanding and addressing these challenges are increasingly in our collective hands.
The City Nature Challenge exemplifies how ordinary people can contribute to extraordinary science, transforming brief encounters with nature into lasting data points that help map the health of our planet 5 7 .
What makes this approach particularly powerful is its ability to operate at multiple scales simultaneously: a child photographs a strange insect in a backyard, which becomes part of a global pattern discernible to researchers studying ecosystem health.
Each observation represents a pixel in a planetary portrait
This isn't just about cataloging what exists; it's about creating baselines to measure change, identifying conservation priorities, and discovering unexpected resilience in urban landscapes 7 .
Whether by participating in next year's City Nature Challenge, reducing our plastic consumption, or simply paying closer attention to the natural world around us, we can all contribute to a future where both humanity and nature thrive.
The first step is simply to notice—to follow nature's challenges with curious eyes, and to add our observations to the growing chorus of data that may well guide us toward solutions.