There's a saying that in a big city you are never more than six feet away from a rat. It's an urban myth, but scientists are warning cities across the globe are becoming far rattier, and the boom is primarily driven by one factor: climate change.
Jonathan Richardson, a biology professor at the University of Richmond, decided to research urban rat trends after seeing media reports of rats taking over cities. These tended to focus on single locations and "usually without a lot of hard data," he told CNN.
He and his team decided to change that. They requested rat stats from the 200 biggest US cities by population, but found only 13 had the quality long-term data they needed. To give more geographical range, the researchers also included three international cities: Toronto, Tokyo and Amsterdam. The data collected spanned an average of 12 years and comprised rat sightings, trappings and inspection reports.
It revealed "significant increasing trends" in rat numbers in 11 of the 16 cities, according to their study, published Friday in the journal Science Advances.
The study linked rat increases to several factors, including high population densities and low amounts of urban vegetation, but the predominant influence was warmer average temperatures.
Read more at the link in our bio.
📸: Nick Lachance/Toronto Star/Getty Images
Efforts to decarbonise the built environment are accelerating, driven by a growing recognition that skills and knowledge are as vital as technology. Across the UK, the green workforce is being prioritised as a cornerstone of sustainable construction, with training in sustainable building design and whole life carbon assessment now central to professional development. Industry leaders warn that without adequate funding for education, progress in reducing embodied carbon and achieving low carbon design targets will stall. The focus on life cycle cost and lifecycle assessment is reinforcing the message that every decision—from material selection to maintenance—shapes the carbon footprint of construction and the sector’s path toward net zero whole life carbon.
Artificial intelligence is entering this transformation, exemplified by Greyparrot’s Analyser, recognised by TIME as one of 2025’s best inventions for its ability to identify and sort construction and demolition waste. The system integrates circular economy principles into real-time waste management, improving material recovery and reducing landfill dependency. Tools like this support circular economy in construction strategies and resource efficiency in construction by extending the life of low embodied carbon materials. With digital monitoring enhancing end-of-life reuse in construction, these innovations could prove decisive in achieving measurable reductions in embodied carbon in materials and demonstrating environmental sustainability in construction at scale.
At a policy level, the European Union’s latest revision to sustainability reporting regulations draws sharp lines between large and small companies. Limiting mandatory accountability to only major organisations could weaken the uptake of sustainable building practices among smaller firms, which collectively represent a significant portion of the industry’s environmental impact. Experts in environmental product declarations (EPDs) and sustainable material specification stress the need for consistent reporting across all tiers to ensure that carbon footprint reduction and circular construction strategies are embedded sector-wide rather than confined to flagship developments.
In the UK, the £2.9 billion transformation of the Sellafield site is being closely scrutinised as a potential benchmark for low carbon construction materials and green infrastructure integration. Public procurement at this scale has the power to drive net zero carbon buildings and eco-design for buildings through the supply chain, from renewable building materials to energy-efficient buildings that meet BREEAM or forthcoming BREEAM v7 standards. The government’s commitment to whole life carbon performance assessments on such projects could pave the way for broader adoption of sustainable building practices, embedding life cycle thinking in construction into mainstream infrastructure policy.
Whole Life Carbon is a platform for the entire construction industry—both in the UK and internationally. We track the latest publications, debates, and events related to whole life guidance and sustainability. If you have any enquiries or opinions to share, please do
get in touch.
