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Rajshahi city’s winter land-surface temperature has witnessed a sharp and spatially concentrated rise over the past three decades, raising renewed concerns about urban planning, thermal comfort and long-term liveability in the divisional city, according to a geospatial study.

The study, conducted jointly by researchers from the University of Rajshahi and The Ohio State University using remote sensing and geographic information system technologies, showed that the average winter land surface temperature in Rajshahi city rose by 2.66C between 1990 and 2023, with some areas experiencing a rise of more than 4C.

This rate of warming, the study noted, is significantly higher than the global average increase of about 0.2–0.3C a decade, as estimated by the Intergovernmental Panel on Climate Change, a United Nations body.

Of the increased 2.66C temperature, 0.63C occurred in 1990–2000, 0.95C in 2000–2010, and 1.08C in 2010–2023.

The research, published in the peer-reviewed journal Sustainability, attributes the warming trend to the loss of green spaces and water bodies, replaced by concrete and other impervious surfaces.

Over the 33-year period, the built-up area in the city increased by about 28 per cent, whereas vegetated and water-covered areas decreased by 26 per cent and 3 per cent, respectively.

During this period, built-up areas expanded markedly from 9.73 square kilometres to 22.99 square kilometres, while vegetation cover experienced a decline by 12.48 square kilometres and water bodies decreased by 1.44 square kilometres.

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Meanwhile, the city’s population surged to nearly one million, growing at an annual rate of 2.88 per cent.

This rapid urbanisation has not been matched by climate-sensitive planning, the study observed.

‘The loss of greenery and water has stripped the city of its natural defences against warming,’ said lead author Md Rejaur Rahman, professor of geography and environmental studies at Rajshahi University and a Fulbright visiting research fellow at The Ohio State University.

Residents, too, are noticing the change.

‘We used to welcome winter with foggy mornings and cool winds,’ said Nahid Islam, a shopkeeper at Ramchandrapur.

‘Now November feels like late summer,’ he said.

A hotspot analysis identified clusters of high-temperature areas in the central-northern, central-western and south-eastern parts of the city.

These zones, once dominated by orchards and ponds, now face significant ecological stress and declining thermal comfort as dense urban construction crowds out natural cooling.

‘Rajshahi’s transformation from agricultural and open land to a dense urban fabric has made the city markedly warmer, even in winter,’ said Rejaur.

‘If remain unchecked, this trend will worsen urban discomfort, health risks and energy demand,’ he said.

‘Urban heat islands intensify respiratory and cardiovascular risks,’ said Shahidul Islam, a Rajshahi-based environmental activist.

‘Rajshahi was once known for clean air and greenery. Without urgent intervention, it risks becoming one of the least liveable cities.’

The study calls for urgent, climate-sensitive urban planning that preserves and expands green and blue networks, prioritises tree cover and water-body restoration in central wards, promotes permeable paving and low-albedo materials, and integrates thermal-comfort criteria into land-use approvals and infrastructure projects.

It also recommends continued satellite monitoring and targeted interventions in hotspot wards.

While Dhaka has long been the focus of urban heat research, the findings from Rajshahi highlight the vulnerabilities of Bangladesh’s other cities.

Moshiur Rahman, chief executive officer of the Rajshahi Development Authority, the government agency responsible for the planned and sustainable development of the city, told ¶¶Òõ¾«Æ· that he had only recently joined and was unaware of the study.