NAO warns of gaps in government climate risk reporting as prisons face flooding and overheating
Nearly nine in ten prisons in England and Wales have been disclosed as facing a high risk of flooding, and more than seven in ten a high risk of overheating. These are not findings from a campaign group or a thinktank. They come from government’s own new climate risk disclosures, reviewed for the first time by the National Audit Office, in a report that gives a mixed verdict on how well the public sector understands the climate risk sitting inside its own estate.
The NAO’s report, published on 2 November, is the first independent assessment of a new requirement: since 2025-26, HM Treasury has required larger central government bodies to disclose the impacts, timelines and costs of their most significant climate-related risks, using a framework based on the Task Force on Climate-related Financial Disclosures. The NAO reviewed disclosures from 31 audited bodies in total, 25 under HM Treasury’s guidance and a further six public corporations and companies reporting under Companies Act rules, which have been doing so since 2022.
The headline finding is that quality varies sharply. Some bodies set out their climate risks and what those risks mean for services, plans and finances in specific, usable detail. Others fall well short of that. Gareth Davies, head of the NAO, put it plainly: “Parliament needs clear information on the resilience of infrastructure, service provision and finances to climate change.” His assessment of where that information currently stands is that most bodies are still at an early stage of understanding and reporting their most important risks.
What government’s own data shows
Two sectors give a sense of what is at stake when disclosure is done properly. Rail operators have been reporting the operational reality of climate risk for some time: flooding, high winds and landslides already delay and cancel services, and the NAO’s review states that losses are expected to rise, with some routes potentially becoming financially unviable, or inoperable altogether, later this century under the worst-case scenario.
The prison estate offers the sharpest single statistic in the report. Disclosures show 89% of prisons at high flood risk and 71% at high overheating risk, findings with direct implications for the health and safety of both staff and prisoners, and ones the prison service says will now feed into its investment planning through climate scenario analysis.
Where that kind of scenario analysis was carried out at all, the NAO found it helped bodies get a handle on future costs, service risk and where to direct investment. The problem is that it was used sparingly. Beyond that, the NAO identified a consistent pattern: most bodies named similar risks, overwhelmingly flooding and overheating, but few went on to fully explain what those risks meant in practice, and most disclosures did not set out enough targets or measures for a reader to judge whether the risk was actually being managed. One point of genuine progress: reporting on the governance and management of climate risk did improve between 2024-25 and 2025-26.
Why this is worth reading beyond Whitehall
It would be easy to file this as a public sector story and move on. That would miss the point. This is one of the largest, most varied property and infrastructure portfolios in the country being assessed, for the first time, against a disclosure framework that private landlords, occupiers and FM providers are increasingly being asked to meet themselves, whether by investors, lenders, insurers or their own boards.
Read that way, the NAO’s review works as a practical diagnostic. It sets out, in plain terms, the difference between disclosure that tells a board something it can act on and disclosure that technically complies but explains very little: specific risks tied to specific assets and services, scenario analysis that reaches an investment decision, and measurable targets a reader can hold the organisation to. Any estates or sustainability team now building out its own climate risk reporting, in any sector, has a free, independently audited example of what good and poor practice actually look like, with no commercial incentive on either side to flatter the picture.
The timing also matters. The report lands a week before COP31 opens in Antalya, where buildings and energy efficiency are on the formal agenda, and in the same month that a separate consultation on overhauling the UK’s wider corporate sustainability reporting regime is due to close. Climate risk disclosure is not settling down. It is still being worked out, by government and private sector alike, and this report is a rare, unvarnished look at how far that work still has to go.
The bottom line
The NAO’s conclusion is not that government is hiding a problem. It is that government, like much of the private sector attempting the same exercise, is still learning how to report a risk it has only recently been required to quantify. Davies expects the reporting to “become more useful over time.” Whether that happens will depend on whether the bodies currently producing thin disclosures close the gap to the best examples the NAO has now put on record, or whether this becomes another compliance exercise that satisfies the requirement without telling anyone much at all.
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