Mérida Named Among World's 50 Most Heat-Vulnerable Cities

Mérida has landed on a global list it would rather avoid: the 50 cities most vulnerable to extreme heat, according to new international research.

The city ranked 47th out of 205 cities studied worldwide in a paper published in the journal Sustainable Cities and Society, led by researchers including a team from the University of Oxford. The study gave Mérida a composite risk score of 0.58, based not just on how hot the city gets, but on how prepared it is to handle that heat.

Researchers measured three factors: heat exposure, the vulnerability of the local population, and the city’s capacity to cope. For Mérida, that combination adds up to what local experts call a dangerous mix — rising temperatures, an aging population, thin urban tree cover and the high cost of cooling a home.

Dr. Silvana Forti Sosa, director of the Urban Laboratory at Universidad Modelo, said reforestation campaigns alone won’t fix the problem. Local and state authorities need to rein in urban growth and stop the deforestation that quietly functions as the city’s cooling system, she said.

Forti Sosa singled out developers who clear lowland jungle to build subdivisions, then plant a handful of small trees to compensate.

“It’s a bit absurd,” she said. “It doesn’t make sense. If we’re betting on greening the city, we also have to prohibit deforestation. That’s how it works, in my head.”

She said Mérida needs stronger land-use planning built around a principle of self-sufficiency — treating undeveloped land as a resource for food production, rainwater collection and renewable energy, including solar and wind power, rather than simply more space to build.

“Right now we have an extractivist model in the city,” she said. “We’re squeezing maximum profit out of the land. That’s why we end up with these huge, half-empty developments with tiny green areas.”

Urbanization itself also needs tighter rules, Forti Sosa said. Mérida has roughly 16,500 hectares (about 40,770 acres) of land available for new development, she said, and how it’s managed will shape the city’s climate future.

“If we were more careful, we wouldn’t have to pave every street, because pavement doesn’t let water through,” she said. “New designs have to account for a changing climate — and a changing subsurface, too.”

The ranking adds Mérida to a growing list of Latin American cities flagged for extreme-heat risk, alongside Manaus and Goiânia in Brazil, Guayaquil in Ecuador and Barranquilla in Colombia. Researchers note the risk isn’t limited to desert regions; tropical cities where urban design amplifies heat can be just as exposed as drier, hotter ones.

The warning echoes concerns raised in past assessments of Mérida’s unchecked growth, which have long flagged deforestation and shrinking green space as side effects of the city’s rapid, market-driven expansion.

The Oxford team says its framework is meant to help city planners look past raw temperature readings toward the underlying factors that turn heat into a health risk. Full findings from the Oxford study are available online.

Fast Facts

Mérida ranked 47th of 205 cities worldwide for composite heat risk
Composite score: 0.58 (out of 1.0)
Study published in Sustainable Cities and Society, led by University of Oxford researchers
Risk factors measured: heat exposure, population vulnerability (age, income) and coping capacity (vegetation, electricity costs, air-conditioning access)
Other Latin American cities on the list: Manaus and Goiânia (Brazil), Guayaquil (Ecuador), Barranquilla (Colombia)
Local voice: Dr. Silvana Forti Sosa, director of the Urban Laboratory at Universidad Modelo

With reporting from Diario de Yucatán and the University of Oxford, with additional context from coverage in Sustainable Cities and Society.