Explosive Increase of 'Rat Swarms' in Major Global Cities... "Disaster Level: Washington Up 390% in 10 Years"

Another Disaster Brought by Global Warming
More Rats in Cities with Higher Population Density and Less Green Space

A study has found that rat populations have exploded in major cities such as the United States and Canada as winter weather has warmed due to global warming.

Jonathan Richardson, a professor at the University of Richmond, USA, and others published a research paper containing these findings on the 31st of last month (local time) in the scientific journal Science Advances. The study targeted 16 cities in total, including 13 U.S. cities such as Washington DC, New York, and San Francisco, as well as Toronto in Canada, Amsterdam in the Netherlands, and Tokyo in Japan.

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These cities either regularly disclose data related to rat sightings or pest control cases or provide aggregated data upon researchers' requests. Many major cities such as London in the UK and Paris in France were excluded from this study because they did not provide such data at all.

Among the cities studied, Washington DC saw the largest increase in rat populations over the past decade, with a growth rate of 390%. Other cities with significant increases during the same period included San Francisco (300%), Toronto (186%), and New York (162%).

Out of the 16 cities surveyed, 11?including Amsterdam, Auckland, Buffalo, Chicago, Boston, Kansas City, and Cincinnati?showed statistically significant increases in rat populations. Dallas and St. Louis showed slight increases or decreases but no statistically significant changes. Only New Orleans, Louisville, and Tokyo experienced decreases in rat numbers.

Regarding these results, Richardson, the first and corresponding author of the paper, explained, "There is no reason to think the situation would be different in other cities."

The proportion of temperature rise contributing to the increase in rat populations in the studied cities was about 40%. Additionally, cities with higher population density or less green space tended to have larger rat infestations.

Professor Richardson noted that in New Orleans, which had the largest decrease among the three cities with declining rat populations, "education on how to prevent rat infestations was conducted," according to the British daily The Guardian. He also suggested that the decrease in Tokyo might be related to cultural norms and high expectations for cleanliness, leading people to promptly report rat sightings.

Meanwhile, various U.S. cities have declared 'war' on rat infestations and are employing various methods, but have not been able to completely stop the rat outbreaks.

Washington DC conducts rat-catching training for property managers and private pest control workers at the city level and even enlists dog owners to have their dogs catch rats. Eric Adams, the former police officer and mayor of New York City, who made rat extermination a key administrative task, created a new high-ranking public official position dedicated to rat extermination called the 'Rat Czar' (Director of Rodent Reduction) in 2023, offering an annual salary of $155,000 (about 220 million KRW). As a result, Kathleen Coradi (35), a former New York City education official, secured the position after beating a 900-to-1 competition ratio.

The qualifications for the 'Rat Czar' include a college degree, document handling skills, and at least five years of experience in pest and harmful animal extermination. New York City also emphasized that "the most important qualities are killer instincts to fight our main enemy, bold action and ferocity, and an aura of rough behavior," highlighting that this position is unlike any other public official role.

In addition, New York City has delayed garbage disposal times from 4 p.m. to 8 p.m., installed rat traps, injected carbon monoxide into rat holes, and is employing various means to win the war against rats. In September last year, the New York City Council passed a bill to conduct a pilot program that sprays contraceptives instead of rat poison to control rat population growth.