If scorching heat waves , destructive storms , prolonged droughts and rising seas aren't enough to make some folks fear the consequences of climate change , perhaps this will do the trick: The warmer it gets, the faster rats multiply in cities that already struggle to contain them. That doesn't include the cost of the diseases the animals spread, such as hantavirus , murine typhus and bubonic plague , nor the mental health toll of living among them. The new findings , reported Friday in the journal Science Advances, are based on records of rat sightings in 16 cities around the world.
Unfortunately for humans, 11 of those cities saw their rat populations expand over the course of the study, while two cities held steady and only three achieved measurable declines. That the rodents are thriving should come as little surprise. They're perfectly suited to urban environments, where they make their homes in walls, basements and subway stations and feast on garbage, sewage, dog poop and abandoned pizza slices. The only continent they have yet to conquer is Antarctica.
One of the few things that slows rats down is cold weather. And with climate change, we have less of it. Read more: Column: Man vs.
Global warming causes average temperatures to rise , which reduces the number of wintry days. In cities, the trend is compounded by the fact that the built environment absorbs and retains more heat than the rural area around it, a phenomenon known as the urban heat island effect.
To investigate a possible link between rat populations and rising temperatures, Richardson and his colleagues searched for reliable data in the country's most populous cities. Conducting a thorough rat census was impractical β if not impossible β so they used municipal inspection logs and rat sightings reported to government agencies.
