On one of the hottest days of the summer, after the warmest spring on record, I – like many others in the city – sought refuge from the heat in the shade of my college garden. At the same time, across Cambridge, in wards such as Abbey and Cherry Hinton – areas with lower average incomes, fewer trees, and limited green space – residents faced streets of concrete and asphalt that trapped and intensified the heat. While students and staff benefit from the University’s exclusive green spaces, many locals face a starkly different reality. As extreme temperatures become the new norm, a pressing question emerges: who gets to stay cool in Cambridge?

“Children, ethnic minorities and the lowest-income groups face surface temperatures up to 4°C hotter than wealthier, predominantly White neighbourhoods”

As the UK enters an era of record-breaking temperatures, with the summer of 2025 confirmed as the hottest on record, extreme heat is becoming one of the UK’s most pressing public health threats. High temperatures increase the likelihood of cardiovascular failure, respiratory distress, heatstroke, and dehydration. Data from the UK Health Security Agency shows that during the 2022 summer heatwaves, England experienced an estimated 2,985 excess deaths, with mortality risk rising sharply once daily maximum temperatures exceed 25°C.

These health risks are not evenly distributed. The old, the young, and those with chronic illnesses are at heightened risk due to reduced physiological resilience. But vulnerability is not only biological; it is fundamentally socio-economic. Low-income households often live in poorly insulated homes with limited ventilation, and face barriers to healthcare and higher rates of pre-existing conditions — all of which increase vulnerability to extreme heat. Racially marginalised communities are also disproportionately exposed; a 2025 spatial study of Greater London, combining satellite imagery with Census data, found that children, ethnic minorities — especially Black and Asian populations — and the lowest-income groups face surface temperatures up to 4°C hotter than wealthier, predominantly White neighbourhoods.

“Urban areas can be 10-12°C hotter than their rural surroundings, driven by the urban heat island (UHI) effect”

The effects of heat are not just unequal across communities, but across environments too, with cities bearing the brunt. A 2024 government report found that urban areas can be 10-12°C hotter than their rural surroundings, driven by the urban heat island (UHI) effect, which amplifies extreme temperatures. This phenomenon intensifies where heat-absorbing materials like concrete, tarmac, and glass dominate, as they store far more heat than natural materials like grass or woodland. Surface reflectivity – or albedo – also plays a role: dark, low-albedo materials such as asphalt absorb more solar radiation than lighter, reflective ones, while a lack of vegetation limits evapotranspiration (the natural cooling process where plants release water vapour) further exacerbating urban heat.

Green spaces are crucial to mitigating the UHI effect. The UK Centre for Ecology and Hydrology estimates that they can reduce temperatures by 2-5ºC through shading and evapotranspiration. The communities most vulnerable to heat, due to age, illness, or poverty, are often the same ones living in the hottest, least green parts of our cities. Those areas ranking lowest on the UK Index of Multiple Deprivation consistently have less tree cover and natural cooling than wealthier areas.

“Communities most vulnerable to heat, due to age, illness, or poverty, are often the same ones living in the hottest, least green parts of our cities”

In Cambridge, this pattern holds: council data shows poorer wards like Abbey and Cherry Hinton have the lowest tree canopy (6.8–7.3%) and little shade, while wealthier areas like Newnham and Trumpington enjoy much more coverage (13–18.8%). As heatwaves intensify, this overlap of social and environmental vulnerability means the same communities are hit hardest—twice over.

While it’s tempting to imagine climate change exclusively in terms of distant catastrophes – Tuvalu sinking, melting Arctic ice, Canadian wildfires – sometimes it’s as innocuous as a hot summer’s day. In an era of rolling heatwaves, access to green space is emerging as a new marker of inequality. So, while our city of gowns and gardens may appear green, it’s high time we ask: green for whom?