The NHS is contending with mounting climate related pressures this year, as Integrated Care Boards work to advance sustainability and net zero commitments during what the Met Office says is on course to be the UK's warmest summer on record.

The scale of the health impact has already become clear. A rapid early assessment by the UK Health Security Agency estimated 2,877 heat associated deaths during heatwaves in May and June this year, almost double the figure recorded across the whole of 2025. Health Secretary Yvette Cooper said the heat had a serious impact on people's health and on the NHS this summer. She said the health service had long prepared for winter pressures and the need to support vulnerable people in cold weather, but was now facing an increasingly serious impact from summer heat as well.

Climate extremes appear to be becoming the norm rather than the exception. Mike Kendon, the Met Office's lead author on the latest State of the UK Climate report, published in July, said conditions once considered extreme were increasingly being treated as normal. The report identified the ongoing rise in temperatures, particularly at the extremes, as the central change shaping the UK's climate.

Cooper said rising global temperatures were creating challenges for the NHS it had not encountered before, describing the need for some immediate acute responses. She said a clearer assessment was now required of what these pressures would mean and what management systems needed to be in place to cope.

A report published by the Climate Change Committee in May went further, describing heat as the deadliest single climate related health threat in the UK. It warned that without further adaptation, excess heat related deaths during heatwave periods could rise from a current range of 1,400 to 3,000 to between 3,000 and 10,000 by 2050, with corresponding increases expected in emergency hospital admissions and attendances. The report said heat and flooding threatened the NHS's ability to deliver quality, accessible care, and called for risk assessments, adaptation plans and dedicated climate funding.

Health policy researchers say ICBs now have a clear incentive to take the issue seriously. Sophie Julian of the Nuffield Trust pointed to record A&E attendances this July, with repeated heatwaves placing additional strain on the NHS at moments when it would previously have expected some respite. Chris Naylor, a senior fellow at The King's Fund and policy lead at the Centre for Sustainable Healthcare, described the data emerging on climate change's impact on the NHS as increasingly alarming, and said any ICB not yet engaging with the issue would need to do so soon.

ICBs and Trusts have operated under a legal duty since the Health and Care Act 2022 to consider statutory emissions and environmental targets, delivered through board approved green plans. This made the NHS the first health system in the world with a legal net zero commitment. Green plans were required to be refreshed by 31 July 2025, guided by NHS England's updated framework covering workforce, medicines, transport and estates.

Progress since the NHS's original 2020 net zero pledge has included a 14% reduction in its direct carbon footprint, a 10% reduction in energy related emissions from facilities, and a 33% reduction in emissions from inhalers and anaesthetic gases. However, Naylor noted that rising patient activity has offset some of these gains, meaning greater carbon efficiency has not yet translated into an overall reduction in the NHS's total footprint.

Research from Brighton and Sussex Medical School found the first wave of green plans, published in 2021 and 2022, was strong on general aims but weak on measurable commitments. Naylor said the second wave, emerging since 2025, marks a clear improvement, with the most progress seen where ICBs focus on a small number of specific, trackable goals such as building related emissions. Julian cited examples including LED lighting, heat pumps and solar panel installations.

Primary care presents a more significant gap. Naylor noted that general practices face no formal sustainability requirements, despite accounting for around 23% of NHS carbon emissions, leaving a substantial share of the health service's footprint outside existing accountability structures. Budget pressures compound the challenge, with Julian warning that sustainability initiatives are often deprioritised when ICB finances are stretched, and that funding opportunities vary unevenly across regions.

Naylor argued that ICBs can add real value through commissioning powers, contractual levers and their convening role across local partners, while stressing the need for practical, achievable priorities rather than broad ambitions. He pointed to medicines manufacture and supply, responsible for around 17% of the NHS carbon footprint, as an area where improved prescribing and reduced waste could deliver both financial and environmental benefits.

His closing assessment was direct. Climate change, he said, is no longer a distant or abstract threat, but a present reality already damaging health and disrupting the delivery of care.

‍