Transforming cities: modelling predicts how climate change could disrupt urban wildlife
Intensifying climate change could radically alter the animal populations living in North American cities.
That is the key finding of the new study “The great urban shift: Climate change is predicted to drive mass species turnover in cities” published last month in PLOS One. The research was led by Alessandro Filazzola, a recent postdoctoral researcher in the University of Toronto Mississauga’s Centre for Urban Environments (CUE).
Filazzola used computer modelling to project the impact of global warming on more than 2,000 terrestrial animal species in the 60 most populated cities in Canada and the United States. He made predictions according to three different scenarios of greenhouse gas emissions and urban land use.
The findings show that across all three scenarios, every city in the study will experience both substantial gains and losses of urban species by the end of this century. In Toronto, for example, 40 to 195 species currently present are predicted to disappear, while 159 to 360 new species could emerge. It’s a similar story for Mississauga.
“Most Canadians live in cities, and the nature we interact with every day is in our backyard or local park,” says Filazzola, who has a PhD in biology and works as a data scientist focused on conserving biodiversity.
“The whole sea change in the assemblage of animals that live in our cities will have a large impact on how we behave in our day-to-day activities and what we value.”
Filazzola conducted the research with biology professor Marc Johnson, the former director of CUE, a transdisciplinary research centre focused on promoting healthy urban environments that sustain all life.
Johnson and U of T Scarborough biological sciences associate professor Scott MacIvor co-supervised Filazzola’s postdoctoral research at CUE. They engaged leaders from Credit Valley Conservation, Conservation Halton and Toronto and Region Conservation Authority to understand their top concerns in managing biodiversity in their regions.
To gather data on animal species, the researchers turned to the Global Biodiversity Information Facility, a free public resource featuring data about all types of life on earth. They modelled the historic and future distributions of 2,019 land-based animals in highly developed cities — 13 in Canada and 47 in the U.S. — with more than 400,000 residents. The computer modelling projections were shaped in part by historical bioclimactically relevant variables for each city, such as average monthly minimum and maximum temperatures and monthly precipitation.
The results forecasted the highest introduction of new species in temperate cities — Quebec City and Ottawa in Canada, and Omaha and Kansas City in the American Midwest. The largest declines in species will take place in the subtropical parts of the U.S. and coastal California. Cities in arid parts of the U.S., such as Las Vegas, and Mesa and Tucson in Arizona, are expected to experience the fewest changes in species richness.
Meanwhile, cities that have historically colder temperatures are predicted to have significantly higher gains in novel species and fewer losses in resident species. Urban areas with historically high precipitation were projected to have the highest species turnover—both the greatest gains and the largest losses. In the scenario with more intense development and greenhouse gas emissions, cities would experience significantly more species lost and gained.
The urban animals expected to be most negatively affected by climate change are amphibians, canines and loons.
“When the modelling predicts a big spike in temperature or a big drop in precipitation, you get a unique climate, and some species can endure it and some cannot — these are the ones that are probably going to be the most impacted and most likely to be lost,” Filazzola says.
The study notes that as urban ecosystems continue to transform due to global warming, shifts in our urban wildlife will have implications for our cultural identity and heritage — given how much animals figure into our national symbols and sports teams, the researchers say — and even our mental health.
“We know that having more green space and natural areas around us is very important for our well-being,” Johnson says. “If we lose nature, and the animals associated with it, it can negatively affect our psychological health.”
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