UK “built for climate that no longer exists” with mounting threats to marine and river habitats, warn government advisers

The UK is “built for a climate that no longer exists” and faces mounting threats to its coastlines, water supplies and marine ecosystems unless urgent action is taken, according to a landmark government report published last week.

The Climate Change Committee (CCC), the government’s independent climate advisory body, released its Fourth Independent Assessment of UK Climate Risk on 20 May, warning that the country is already paying around £60bn a year in climate-related costs, equivalent to roughly 2% of GDP, and that figure could reach £260bn a year within two decades without significant adaptation investment.

Coastal and marine threats

For marine and coastal professionals, the report’s findings on sea level rise, flooding and coastal erosion are particularly stark. Sea levels are projected to rise by 20cm to 45cm around UK coasts by 2050, driving up both the frequency and severity of coastal flooding. Storm surges that currently occur once every hundred years could, by the end of the century under a 4°C warming scenario, become annual events.

The number of UK properties at risk of flooding, currently around seven million, could increase by up to 40% by 2050 without action, with peak river flows potentially 45% higher and heavy rainfall intensity rising by up to 60%. The CCC projects annual flood damage rising from £3.3bn today to £4.5bn by mid-century, and calls for sustained investment of between £1.6bn and £2.2bn per year in flood risk management to hold overall risk at current levels.

The report makes clear that natural flood defences alone, including wetland restoration and river rewiggling, will not be sufficient. Engineered infrastructure remains essential alongside nature-based solutions. The CCC proposes a target of keeping the total number of properties impacted by flooding no greater than today’s level by 2050.

Water scarcity and drought

Inland, the picture is equally challenging. The report warns that river flows are likely to be around a third lower in summer than they were 20 years ago, and that by 2050 the shortfall in England’s public water supply could reach five billion litres per day – equivalent to around 2,000 Olympic swimming pools. Parts of South East England remained in drought until January 2026 following prolonged dry conditions in summer 2025.

Julia King, chair of the CCC’s adaptation subcommittee, set out the scale of the water challenge directly. “We are facing a potential world where in 2050 you could turn the tap on and nothing would come out,” she told the Guardian. “We need more new reservoirs. We need to be able to move water around the country. We need to address leaks, and we need to address water efficiency.”

The committee sets a target of water supply being resilient to a one-in-500-year drought by 2040.

Nature recovery at risk

The report also raises significant concerns about the UK’s capacity to meet its nature restoration commitments under a changing climate. It warns that the UK is already one of the most nature-depleted countries in Europe, and that without additional adaptation, there is a risk of widespread ecosystem loss by 2050, including globally significant chalk streams. Small, fragmented habitats created through current restoration programmes may prove too vulnerable to sustain biodiversity as conditions shift.

The CCC calls for 30% of land to be protected for nature by 2030 and in good ecological condition by 2050, but stresses that protection designations must become forward-looking, based on where species and habitats can thrive under future climate conditions rather than historical baselines.

The investment case

The committee estimates that the adaptation measures identified in the report would cost approximately £11bn a year, shared between public and private sectors, a fraction of the UK’s total annual investment of around £547bn. Every £1 spent on adaptation, it calculates, would yield around £5 in benefits.

King was unequivocal about the political stakes. “With the right decisions, we can protect the people and the places we love,” she said. “So, the strong message is that decline is a choice, it’s a political choice, it’s not inevitable. We can do something about it.”

Emma Howard Boyd, a professor in practice at the London School of Economics, argued that the report’s coastal and heat-related findings demanded equal weight in national resilience planning: “Heat resilience cannot continue to be treated as an afterthought. It belongs alongside flood preparedness and water security at the very top of the national resilience agenda and the wider prosperity of the UK.”

The government’s response was cautious. Environment secretary Emma Reynolds made no new financial commitment, saying the government was “already acting” and had “invested a record £2.65bn to repair and build flood defences, protecting tens of thousands of homes and businesses.” None of the UK’s existing national adaptation plans was found by the CCC to be fit for purpose.

The full report, A Well-Adapted UK, covers 14 systems including health, land, water, energy, and the sea, and is the most comprehensive UK climate risk assessment to date.

This article was first published by Ocean and Coastal Futures here

Photo Credit: Chris Pagan (@chris_pagan) | Unsplash Photo Community