Carlos Moreno’s Urban Improvement Efforts Under Attack by Conspiracy Theorists.

Carlos Moreno, a scientist and business professor at Sorbonne University in Paris, has been facing a deluge of conspiracy theories and death threats in recent weeks. Moreno is the man behind the popular urban planning concept called the 15-minute city, which suggests that everyday destinations such as schools, stores, and offices should be only a short walk or bike ride away from home. However, the conspiracy theorists have taken aim at Moreno’s proposal, claiming that 15-minute cities are a precursor to “climate change lockdowns” and urban “prison camps” in which residents’ movements would be surveilled and heavily restricted.

The false claims have circulated online, at protests, and even in government hearings, driven in part by climate change deniers and backers of the QAnon conspiracy theory. Moreno has faced harassment in online forums and over email, with people accusing him without evidence of being an agent of an invisible totalitarian world government. He has even received death threats, with people proposing that he be nailed into a coffin or run over by a cement roller.

Moreno’s work has not been focused on the pandemic, though his 15-minute cities idea has become more popular since it began. Like many of his academic peers who have faced harassment and disinformation campaigns, he is at a loss for ways to protect himself. Academics, he said, “are relatively alone.”

Moreno’s idea owes much to its many predecessors: “neighborhood units” and “garden cities” in the early 1900s, the community-focused urban planning pioneered by the activist Jane Jacobs in the 1960s, even support for “new urbanism” and walkable cities in the 1990s. Critics of 15-minute cities have been outspoken, arguing that a concept developed in Europe may not translate well to highly segregated American cities.

Efforts to adopt low-traffic neighborhoods (LTNs), which were approved for testing last year in centuries-old Oxford, have drawn concerns about whether the traffic reduction measures could cause congestion to spill into surrounding areas or make some properties less accessible. Some people, however, seized on other elements of the plan, including cameras meant to monitor license plates.

The result, according to misinformed conspiracy theorists: A nightmare scenario in which residents would be confined in open-air prisons fenced off into siloed zones. On Feb. 18, when an estimated 2,000 demonstrators converged at a protest in Oxford, some carried signs claiming that 15-minute cities would become “ghettos” created by the World Economic Forum as a form of “tyrannical control.”

The vitriol currently directed at Moreno and researchers like him mirrors “the broader erosion of trust in experts and institutions,” said Jennie King, head of climate research and policy at the Institute for Strategic Dialogue, a think tank that studies online platforms. Modern conspiracy theorists and extremists turn the people they disagree with into scapegoats for a vast array of societal ills, blaming them personally for causing the high cost of living or various health crises and creating an “us-versus-them” environment, she said.

The ramped-up rhetoric and the disintegration of safeguards have caused many people in the academic community to flee forums like Twitter for more niche sites like Mastodon, Ms. King said. Last year, the American Psychological Association published a feature suggesting that universities form safety offices to help professors filter menacing messages, scrub their personal information from the internet and gain access to counseling.

Moreno said he did not understand the intensity of the hate directed at him. “I am not a politician, I am not a candidate for anything — as a researcher, my duty is to explore and deepen my ideas with scientific methodology,” he said. “It is totally unbelievable that we could receive a death threat just for working as scientists.”