A new study has found a significant increase in rat populations across major cities, with rising temperatures being the primary factor.
Despite efforts by authorities worldwide, rats remain a persistent presence in urban areas. However, researchers now suggest that climate change is a major contributor to the surge in rodent populations.
Growing Rat Populations in Major Cities
Scientists analyzed data from 13 major U.S. cities, along with Toronto (Canada), Tokyo (Japan), and Amsterdam (Netherlands). The study examined 12 years of records, including rat sightings, capture reports, and inspection data.
Findings showed a “significant upward trend” in rat populations in 11 of the studied cities. Washington, D.C., San Francisco, Toronto, New York, and Amsterdam faced the worst infestations, while only three cities—New Orleans, Louisville, and Tokyo—experienced a decline in rodent numbers.
The study linked the rat population growth to various factors, including high population density and limited urban greenery. However, the most influential factor was the increase in temperatures. The research was published in Science Advances.
Warmer Climates Boost Rat Activity
Scientists explain that rats, as small mammals, prefer warmer environments. Higher temperatures allow them to spend more time foraging and reproducing, leading to significant population growth.
A prolonged warm climate, driven by climate change, creates ideal conditions for rat proliferation. Additionally, food and waste odors become more detectable to rodents under these circumstances.
Public Health and Economic Impacts
Researchers warn that rising rat populations bring multiple challenges. Rats cause an estimated $27 billion in damages annually in the U.S. and pose serious health risks, being linked to over 50 diseases.
There is also growing evidence that rat infestations have a “major impact on mental health” for residents living in affected areas.
