Thousands of animal species will soon vanish from cities

A new study led by the University of Toronto Mississauga has examined how climate change might fundamentally alter the animal species populating North American cities. 

Shedding new light on the potential future shifts in urban biodiversity, this research has major implications for the animals that city residents may encounter by the year 2100.

Biodiversity landscape of US and Canadian cities

Urban areas, teeming with life, offer residents the opportunity to connect with local biodiversity, ranging from birds in backyards to animals represented as local sports team mascots. 

However, the experts warn that the biodiversity landscape of US and Canadian cities could undergo significant changes due to human-induced climate change, affecting over 2,000 animal species that have historically inhabited the 60 most populous cities in North America.

“Just like the California grizzly bear is extinct from where it is displayed prominently on the state flag, with climate change, the floodgates are open and many other emblematic species are at risk of extirpation from the communities they represent,” noted the study authors. 

Climate change causes widespread biodiversity shifts

“Human experiences with nature are important for our culture, economy, and health. Anthropogenically-driven climate change is causing widespread shifts in biodiversity and resident urban wildlife are no exception,” wrote the researchers.

“We modeled over 2,000 animal species to predict how climate change will impact terrestrial wildlife within 60 Canadian and American cities. We found evidence of an impending great urban shift where thousands of species will disappear across the selected cities, being replaced by new species, or not replaced at all.” 

“Effects were largely species-specific, with the most negatively impacted taxa being amphibians, canines, and loons. These predicted shifts were consistent across scenarios of greenhouse gas emissions, but our results show that the severity of change will be defined by our action or inaction to mitigate climate change.”

Favorable conditions for animal species

The study leveraged data from online species distribution databases, primarily collected through citizen science initiatives, to compile records of terrestrial animal sightings across these cities. 

Despite acknowledging potential inaccuracies in citizen-sourced data, the team employed machine learning techniques to forecast the most favorable conditions for each species under three different emissions scenarios by the end of the century.

Substantial turnover in urban biodiversity

The findings project a substantial turnover in urban biodiversity by 2100, affecting nearly all cities studied. Particularly, cities with a rich history of species diversity are expected to see significant declines, with minimal gains in new species. 

Cooler cities will gain more animal species

Geographical analysis predicts that cooler, wetter cities such as Omaha and Kansas City might welcome a surge of new species, with cities like Quebec, Ottawa, and Winnipeg potentially nearly doubling their current species count. 

Warmer cities will lose more animal species 

Conversely, warmer cities with high precipitation levels, like those in coastal California, may witness the largest exodus of species. Arid regions, exemplified by Phoenix and Albuquerque, might see less dramatic shifts, attributed to their ecosystems’ inherent resilience.

Most bird and insect species will shift to new urban areas

Alarmingly, up to fifty-four species could disappear from the analyzed cities. A taxonomic breakdown reveals that over 95% of bird and insect species could see changes in their urban distribution. 

Canines, most amphibians, and loons are among those anticipated to suffer the most significant losses, whereas turtles, mice, toads, and pelicans might become increasingly prevalent.

Noticeable shifts in the local species composition

According to the researchers, residents who spend their lives in the same city will likely witness noticeable shifts in the local species composition. 

While the study’s predictions are based on models and necessitate further ecological validation, it emphasizes the crucial role of mitigating greenhouse gas emissions in preserving urban biodiversity.

“For people living in cities, the animals in their backyards and local green spaces are going to change significantly with climate change. Over the next few decades, familiar species will be leaving the city and new species will be entering it, forever changing the composition of urban animals,” the authors concluded.

The study is published in the journal PLoS ONE. 

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