In the early 20th century, more than a million miners in Britain made a daily descent into the depths of the Earth to extract coal, the country’s main source of energy at the time. Joining them on their journey to the harsh, dark underground: bright yellow canaries, about the size of a coffee cup. 

These typically loquacious birds were used as a tool. When the canaries fell silent or passed out, miners knew that toxic carbon monoxide was permeating the air and they had to evacuate quickly. The species and this technique gave rise to the phrase “canary in the coal mine”—a refrain used to refer to early indicators of potential hazards. 

A wide body of research shows that a variety of other animals and plants also hold clues for how heavy metals, noxious gases and other toxic substances spread through our environment and what it could mean for human health. 

A new study argues that preserved natural history museum collections are a largely untapped resource for mapping the pollutants of our past, which could inform how they are managed in the present.

Environmental Sentinels: In recent years, engineers have developed high-tech sensors to monitor environmental hazards like gas or heavy metals, but these tools can be expensive to implement at a broad scale. Sometimes the best and most cost-effective way to monitor threats is by testing the species that are immersed in these ecosystems and often live alongside humans, experts say. 

For example, testing fish like gar can help measure toxic metals like mercury and cadmium in the Lower Mississippi River, which pose public health concerns to local communities. 

Meanwhile, research published in 2024 shows the dark toxic burden that house sparrows and children share in lead-mining cities around Australia. Blood samples from hundreds of sparrows captured at more than 40 sites showed high levels of lead in the birds, which live in close proximity with humans. 

With this in mind, the scientists compared their findings to data of blood-lead levels in children in the area and saw a strong correlation. 

The birds and the children with the highest levels of lead in their blood were located in the same areas. The study also showed that blood-lead levels in birds could roughly predict lead exposure in children in different communities. 

Animals could also help us track the history of human-driven climate change. Corals provide a wealth of environmental data for scientists due to their consistent growth and long lifespans. For a 2024 study, researchers took samples from coral skeletons from a reef in the Mediterranean Sea off Spain and tested the marine creatures for spheroidal carbonaceous particles, a pollutant emitted from burning fossil fuels. 

The researchers found that the corals showed a significant increase of contamination between 1969 and 1992, a period of industrialization and high coal consumption in Europe. They say that this provides evidence for the start of the Anthropocene epoch—the modern geological era in which human activities have posed a dominant impact on Earth’s climate and ecosystems. 

“The discovery of these pollutants embedded in coral skeletons extend over decades and paint a clear picture of how extensive human influence is on the environment,” lead author Lucy Roberts, an environmental geochemist at University College London, said in a press release. “​​This is valuable to researchers trying to better understand the history of human impact on the natural world and serves as a powerful reminder of how extensive human influence is over the environment.”

Pollution Time Machine: It’s not just living animals that carry remnants of humanity’s toxic footprint. Samples of bird feathers, fish tissues and other materials hold traces of pollutants that can serve as “environmental archives,” according to a study published in May. 

This strategy could be crucial for filling in data gaps on the historical pollution record, lead author Shane DuBay told me. 

“We really only start monitoring pollutants in the environment once they’re already a problem, so once they’re already having adverse effects on animals [and] on humans, and at that point we really have no understanding … of how we got to where we are,” said DuBay, a biologist at the University of Texas at Arlington. “These specimens that exist in collections around the world have incidentally captured environmental samples from places and times that we can never return to, so we can use them to backfill the environmental record.” 

He added that this approach has already been used to influence public health policy. In the mid-20th century, researchers analyzed a time series of bird eggs from natural history collections to uncover how the insecticide DDT was causing bird eggshells to thin, so much so that they would crack when parents sat to incubate them. 

This finding, featured in scientist Rachel Carson’s famous book “Silent Spring,” contributed to an eventual ban on DDT. The new study argues that this type of data can also reveal a legacy of environmental justice issues in low-income and minority communities, which bear an outsized brunt of pollution in the U.S.

There are limitations to the strategy of tracking toxics through museum collections. Sometimes historical collection data doesn’t include exactly where or when a sample was collected, and the preserved animals may not be evenly distributed across geographic locations. But each bit of data adds a crucial piece to the pollution puzzle, DuBay says. 

“We can put regulations now on how much is being emitted into the environment, but that doesn’t really say anything about what already has been in the environment and will stay in the environment and we will continue to interact with,” DuBay said. “So knowing where that is and which communities, both human and nonhuman, are interacting with those [pollutants] can help us really design a future that mitigates their harm on us.”

More Top Climate News

Jeremy Greenberg, the head of the Federal Emergency Management Agency’s National Response Coordination Center, submitted his resignation earlier this week, Nicole Sganga and Michael Kaplan report for CBS News. His decision follows President Donald Trump’s pledges to phase out FEMA, which coordinates response efforts to extreme weather events such as hurricanes and earthquakes. Greenberg’s resignation comes in the midst of wildfire season and the Atlantic hurricane season. 

One current FEMA official told CBS News, “He’s irreplaceable. The brain drain continues and the public will pay for it. I don’t see how FEMA will find someone who can coordinate with national, state and local emergency organizations like he did.” 

Meanwhile, weeks after the House ditched a proposal to sell off hundreds of thousands of acres of public lands in the Western U.S., Senate Republicans pitched a new proposal to sell millions of acres of public lands across 11 states to build housing, Brad Plumer reports for The New York Times. The new proposal was submitted in draft legislation as part of Trump’s “big, beautiful bill.” Republican Sen. Mike Lee from Utah says the proposal would turn “federal liabilities into taxpayer value, while making housing more affordable for hardworking American families.”

Zoë Rom reported for Inside Climate News that public lands are largely not suitable for affordable housing. Environmental groups say the bill also lacks affordability requirements in its current form. 

“This is a shameless ploy to sell off pristine public lands for trophy homes and gated communities that will do nothing to address the affordable housing shortage in the West,” Jennifer Rokala, executive director of the Center for Western Priorities, a conservation advocacy group, told The Times. 

Young members of immigrant farming families in Santa Maria, California, are protesting deportations under the Trump administration, David Bacon reports for Civil Eats. This small city and the surrounding area are known for abundant strawberry harvests, which peak in the spring and summer. However, around 80 percent of the resident farm workforce is undocumented, juggling the busy season of work with fear of Immigration and Customs Enforcement agents detaining them. 

Of any city in Santa Barbara and Ventura counties, “Santa Maria has been hit the hardest,” Hazel Davalos, co-executive director of the Central Coast Alliance United for a Sustainable Economy, told Civil Eats. “Because of our know-your-rights work, it’s hard for ICE [Immigration and Customs Enforcement] agents to catch people at home, so they concentrate enforcement in public spaces.”

Kiley Price

Reporter

Kiley Price is a reporter at Inside Climate News, with a particular interest in wildlife, ocean health, food systems and climate change. She writes ICN’s “Today’s Climate” newsletter, which covers the most pressing environmental news each week.

She earned her master’s degree in science journalism at New York University, and her bachelor’s degree in biology at Wake Forest University. Her work has appeared in National Geographic, Time, Scientific American and more. She is a former Pulitzer Reporting Fellow, during which she spent a month in Thailand covering the intersection between Buddhism and the country’s environmental movement.

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