Rats worldwide are enjoying the perks of climate change
Climate change is contributing to a global rise in urban rat infestations, according to a new Science Advances study.
As temperatures increase, rats are better able to thrive -- even in inclement weather that would typically deter the population's growth, the article explained.
Temperatures in urban settings have been projected to rise between 1.9 degrees and 4.4 degrees by the year 2100 due to greenhouse gas emissions, according to the study.
"So we imagine it probably increases their survival over the winter. And we're pretty sure that that increased food intake also will lead to more reproductive bouts for these rats, which can accelerate population growth," Jonathan Richmond, the study's lead author and professor of biology at University of Richmond, told ABC news.
Richardson also suggested that less vegetation, along with denser living conditions and strapped rat control resources, are helping rats thrive in many North American cities.
The study, which examined public complaint and inspection data in 16 cities worldwide, found that most places had increased rat growth trends. Some places are managing the "ratpocalypse" better than others, the study found.
In Washington, D.C., for example, the rat population is growing 1.5 times faster than it is in New York City, because the more northerly city has taken notable steps to keep rodents in check. In New Orleans and Tokyo – two cities with robust rodent response teams and good citizen reporting systems – the rat populations appear to be shrinking.
Richardson said that cities experiencing declines might be outliers, rather than part of a broader trend, though he did note that in Tokyo, residents seem willing to post rat sightings on social media in a "name and shame" approach to getting businesses to clean up their act.
There are several reasons to be concerned about potential rat boom.
"Rats transmit more than 50 zoonotic pathogens," Richardson said. "They're a big a big potential vector for people getting sick with some of those pathogens and the diseases they cause."
Kathleen Corradi, the citywide director of rodent mitigation and the so-called "rat czar" of New York City, added that rats are also bad for mental health -- citing a previous study suggesting that experiencing rats on a daily basis increases the risk of depression more than fivefold.
"And when you look even deeper at income level and demographics, it gets even more significant for lower incomes, non-white communities around white individuals," Corradi explained.
Richardson emphasized that controlling rat populations isn't just the city's responsibility. Residents also have to pitch in to keep rats at bay, and city-led efforts to educate residents on understanding rat control can help.
"The everyday person can play a role in this in terms of making sure their own properties don't have conditions that support rats, securing their own food waste, making sure their garbage ends up in a containerized dumpster or garbage can," he said.
Corradi agreed, adding that composting or otherwise removing food scraps from the garbage means "you're already doing a tremendous job to cut off rats' access to food."
She said that New York City, for one, is tackling its rat problem by cutting off the creatures' food supply through widespread use of garbage containers and by educating its residents on prevention. Also helping to combat the program is the city's Rat Pack program, which empowers New Yorkers to take action by learning how to keep their neighborhoods vermin-free, Corradi explained said.
However, as cities warm up, the efforts will have to expand to stay ahead of the problem, Richardson warned.
"I think it's important that we have to move away from traps and rodenticide poisons as the main solution," he said. "Cities have to start really embracing this concept of integrated pest management, where instead of just applying poison baits, most of their efforts are dedicated to eliminating those conducive conditions that support the rats."
City residents are encouraged to report sightings through local hotlines like 311 to help officials track and control rodent populations.
Dr. Christopher Wachuku is an internal medicine preliminary intern at Lankenau Medical Center and a member of the ABC News Medical Unit.
