Newsletter #16 (May 2026)

A SLIGHTLY TECHNICAL MESSAGE OF HOPE: 

Dear all, 

Back from two weeks of leave, I came back to find a technical report for the Climate Change Committee’s big new risk assessment waiting on my desktop. It’s not exactly a page-turner but it remains an uplifting and deeply hopeful and nonsense free analysis. 

So today, I wanted to give you a quick summary of the key facts and findings and why this is, in my view, one of the most powerful cases to date for an ambitious agenda for flood defences.

How to understand the report: 

Under the world-leading Climate Change Act 2008, the UK government has an independent advisor, the Climate Change Committee, that advises it on the risk to the country every number of years. In May, it published its fourth ‘risk assessment’, CCRA4. 

Most people I’ve met can see that the weather is changing and driving increased flood risk. What the technical report does is put numbers to this problem and paint a vision of what the future can look like depending on what the UK does as a nation. 

It is basically telling us, “here is what the nation’s future flood risk could look like in various scenarios” by applying a kind of formula: 

Today’s flood risk 

• Increase from climate change

• Increase from new buildings 

• Decrease from investment

= Future flood risk 

We can build our way out of the worst: 

Basically, the graph below shows that it is not too late to keep in check the increased flood risk we are all dealing with in our day-to-day if the nation delivers an ambitious agenda of work. With extremely high ambition, we can bring flood risk down and improve people’s lives even relative to today. 

I should note that even these calculations assume very very bad climate change, meaning that successful climate action would make these goals even more achievable for flooded people. 

Flooded people will, sadly, know a lot about benefit-cost ratios. There is good news (shown in the graph below) on this front: It is still benefit cost positive to be extremely ambitious with flood risk reduction. 

We are often told we can’t build our way out of this. The graphs above say we can build our way out of the worst. 

The warning: 

Hot air carries more water, meaning more extreme rainfall events. Also, the UK’s waves are largely a function of depth of water, and rising sea-level rise can catastrophically increase overtopping of defences making people’s lives impossible. 

The UK’s flooded people are already on the frontlines of this. And failure to heed the Climate Change Committee’s warnings could make their lives much more challenging than it already is. The maps below give us a sense. 

This is how peak flow of rivers changes as a result of increased temperature according to the best maths we have. The challenge with this is that even places that are currently defended could become vulnerable as the design specs of these defences are exceeded. 

The takeaway: we move forward 

The Climate Change Committee has given us a great gift in the form of a technical and highly authoritative argument for what we all want: maximum ambition to keep our houses safe. 

The report says that what we all need is possible and economic, even if we fail to contain the worst of climate change. The better we do at containing climate change, the more affordable protecting homes are. 

Given the current gaps in funding and implementation, the CCC’s report and advisories will remain essential tools for scrutiny and accountability. They provide the evidence needed to challenge decision-making and guide Government in setting out a pathway towards a safer and climate-resilient future.