City Rats Are Thriving In Climate Change And Living Their Best Lives
Because of humans, rats are currently living their best lives. Aside from leaving food waste and trash in dumpsters for them to eat and providing cozy homes for them in our buildings and sewers, we also heat up the climate by burning fossil fuels. Now, how exactly does that benefit rats?
According to a new study, rising temperatures seem to be helping rat populations grow in cities, even as human inhabitants suffer. To tackle this issue, more resources will be required from cities.
“In cities that have experienced the fastest warming temperatures, they tended to have faster increases in their rat numbers as well,” said Jonathan Richardson, the lead author of the study and an urban ecologist at the University of Richmond.
“Females will reach [reproductive] maturity faster. They’re able to breed more, and typically, their litters are larger at warmer temperatures in the lab.”
The research team examined public complaints about rats and inspection records from 16 cities between 2007 and 2024 to get a sense of how much rat populations have grown. During that period, rat numbers skyrocketed in 11 of those cities.
Washington, D.C., gained the most rats with a 390 percent increase, followed by San Francisco at 300 percent, Toronto at 186 percent, and New York City at 162 percent.
At the same time, some cities saw a decrease in their rat populations, including New Orleans, Tokyo, and Louisville, Kentucky, due to better pest control.
Climate change can directly affect rat populations since rats adjust their behavior to the temperature. When it’s cold out, the rodents tend to huddle underground and spend less time above ground searching for food because it’s a challenge for them to maintain a stable body temperature.
Once the weather warms up, rats will emerge, scavenge for food, and bring the food back to their nests for storage. Warming winters give them more time to forage and reproduce.
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“If the weather stays warmer a little bit later into the fall or into the winter, or if the spring starts a little bit earlier, just by a week or two, that should allow the rats to be aboveground, forage for a little bit longer, secure more food resource and presumably turn that into baby rats,” said Richardson.
Global temperatures are rising, but they’re especially extreme in cities due to the urban heat island effect. Buildings and concrete absorb the sun’s energy, hiking temperatures up to 27 degrees Fahrenheit higher than in rural areas.
At night, that heat is released, making it a danger for city dwellers in the summer. But in the winter, that extra heat could be keeping rats warm, helping them be more successful.
The trouble with controlling rat populations in cities as temperatures rise is that no one knows exactly how many there are. In addition, rat management programs are understaffed and under-resourced.
The key to controlling rats is to control our own behavior. Humans can manage food waste better and limit access to trash.
Building owners can rat-proof their structures, and anyone who sees rats should call the city for eradication.
The study was published in the journal Science Advances.
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