VIDEN
If you live in a city, you’ve probably noticed something: rats are everywhere. They scurry down back alleys, rummage through bins, and sometimes even make their way into homes. But what if I told you that rat populations aren’t just growing because of bad rubbish habits—they’re being fuelled by climate change, rapid urbanisation, and sheer human numbers?
3 main drivers why rats are booming in so many places
- Warming temperatures – As winters get milder, rats survive longer and breed more often. Cold weather once kept populations in check, but climate change is tipping the balance in their favour.
- Urbanisation – The more concrete, the fewer green spaces. And the more buildings, restaurants, and rubbish bins—perfect habitats for rats.
- Human population density – Quite simply, more people equals more food waste and more hiding places.
Put these together and you’ve got a recipe for a rodent surge that shows no sign of slowing down.
That’s the finding of a global study published in Science Advances (Richardson et al., 2025), which analysed long-term rat complaint and inspection data from 16 cities worldwide. The results were striking:
- 11 out of 16 cities showed significant increases in rat populations.
- Cities like Washington D.C., New York, and Amsterdam had some of the steepest rises.
- Only three cities—Tokyo, Louisville, and New Orleans—actually saw rat numbers fall.
Why It Matters
Rats can:
- Damage property and infrastructure, costing billions globally.
- Contaminate food supplies.
- Spread diseases like leptospirosis, hantavirus, murine typhus, and even plague.
- Affect mental health, with studies showing that simply living in rat-infested areas can increase stress and anxiety.
And here’s the kicker: traditional methods like rat poison often backfire. Rodenticides harm other animals (like birds of prey and domestic pets), can lead to poison resistance in rats, and rarely deliver long-term results.
Enter the “Rat Blocker”
One of the more promising modern solutions is surprisingly simple: rat blockers.
These are one-way devices fitted into drains and sewer systems that let wastewater flow out but prevent rats from coming up into streets, gardens, and homes. Since sewers are a superhighway for urban rats, blocking their escape routes can drastically cut the number that ever make it above ground.
Combined with secure waste containers and better sanitation, rat blockers could reduce rat-human contact without relying so heavily on poisons. Several cities in Europe, including parts of the UK and Scandinavia, have already started rolling them out with encouraging results.
Lessons from Cities That Won
The few cities where rat numbers fell—like Tokyo and New Orleans—show that smart strategies work.
- Tokyo benefits from a culture of high hygiene and public accountability: people quickly report and share unsanitary conditions.
- New Orleans invested in proactive surveillance and community education rather than waiting for infestations to get out of hand.
The takeaway? Rat control isn’t just about killing rats—it’s about making cities less rat-friendly.
The Road Ahead
Urbanisation isn’t slowing down. The UN projects the global city population will grow by 25% by 2050, while climate models predict even warmer, longer summers in most metropolitan areas. That means more rats—unless we act now.
An integrated approach is needed:
- Waste management reform – secure bins, faster collection, less rubbish on streets.
- Environmental design – more green space, less clutter where rats can hide.
- Infrastructure tools – widespread use of rat blockers in drains and sewers.
- Public education – empowering residents to report infestations and reduce food waste.
Cities may never get rid of rats completely. But with smarter strategies—and the right tools—we can keep their numbers under control and make urban life a lot more pleasant for the people who live there.
By Tony Vogel – Nordisk Innovation Ltd
