The aviation climate disruption risk facing UK and European airports is growing, as climate scientists and industry figures warn that more powerful storms, rising sea levels and worsening clear-air turbulence could make the chaos seen at Heathrow and Gatwick this summer a recurring reality. Around 900 flights to and from the two airports were delayed in late June, some by up to 11 hours, when thunderstorms forced air traffic controllers to reroute aircraft around congested airspace and left planes waiting on the ground. Dozens more were cancelled entirely.
For passengers at airports across Europe who had been hoping to fly into London, the disruption meant long waits and uncertainty at a time when the holiday season was barely under way. The weather has since moved on, but the events of that Saturday have prompted a serious debate inside the industry about whether the UK’s crowded skies are sufficiently prepared for a warmer, stormier world.
The scale of what controllers manage every day
To understand the stakes, it helps to grasp how much traffic flows through UK airspace in normal times. NATS, the body responsible for air traffic control across the UK, handles around 2.5 million flights and more than 300 million passengers travelling through UK airspace every year. Its main control centre sits at Swanwick in Hampshire, where Terminal Control staff monitor flights heading to and from London and southern England. NATS also operates a second area control centre at Prestwick in Scotland, according to Copperchase.
On a visit to Swanwick on a hot and humid day, with dark clouds gathering and heavy downpours already hitting the surrounding region, staff were carefully tracking storm cells on large radar screens while scrutinising weather forecasts. Air traffic comes in waves, and with activity expected to intensify through the afternoon, controllers were already preparing for a difficult few hours. Stormy weather shrinks available airspace, forcing traffic to be restricted and rerouted. If aircraft cannot land at one airport, they may be diverted to another, but an already busy airport receiving large numbers of unscheduled planes may simply not have the infrastructure to cope, and can refuse all but emergency traffic.
The vulnerability of this system was made plain in another way just over a year before the June storms. In August 2023, a bank holiday weekend problem with a single aircraft’s flight plan caused a key system at Swanwick to break down, leading to cancellations and delays that affected 700,000 passengers, according to BBC News. That incident had nothing to do with weather, but it illustrated how quickly disruption can cascade through a system operating with little slack.
Aviation climate disruption risk: expert views diverge
Tim Atkinson, an airline risk consultant and former pilot, believes the region’s crowded skies make it especially exposed to climate-driven disruption. He warns of a scenario in which storms simultaneously affect Heathrow, Gatwick, Luton and Stansted, leaving aircraft arriving from across the Atlantic and a large number of European flights all searching for somewhere to land, some with dwindling fuel reserves. ‘What we’re seeing now is very rapid climate change,’ he says. ‘We’re going from the kind of weather activity which takes out an airport, and which the system kind of copes with, to a situation where, with very little predictability, it would be possible to lose all of the London airports from real-time operation quite swiftly and with little notice.’
Such a scenario could, in his view, create ‘a very serious risk event, such as an aircraft running out of fuel in the sky’. Aircraft are legally required to carry enough fuel to reach an alternative airport if needed, plus an additional 30 minutes of flying time on top of that.
Andrew Charlton, who manages the Swiss-based consultancy Aviation Advocacy, takes a more measured view. ‘You’ve always got to imagine the worst-case scenario,’ he says. ‘But I also think we need to keep that worst case in context. Yes, it’s possible to imagine it. But I’m also fairly comfortable with the ability of this industry to react well and make good decisions.’ He is clear that this is not, in his words, ‘the top of that list’ of concerns that keep him awake at night.
If storm delays do become more frequent, Charlton says airlines will have to carry more fuel as a standard precaution. Fuel is one of the largest costs an airline faces, and a higher fuel bill, he says, will inevitably be passed on to passengers in the form of higher fares. ‘Aircraft are going to have to fly further, and they’re going to have to factor in the assumption they’re going to fly further,’ he says.
The underlying science lends weight to the concern, even if it does not settle every question. Thunderstorms are driven by convective activity: warm, moist air rises rapidly, expands, cools, and forms large clouds. More heat provides more convective energy. For every degree the Earth warms, the atmosphere can hold about 7% more moisture, increasing the probability of heavy rainfall. Studies have shown that higher latitudes, particularly in the northern hemisphere, will see the biggest increases in conditions favourable to storm formation, and those storms may be more violent. The UK’s Met Office has said that while the total number of thunderstorms may not rise, ‘the ones we do experience could be more impactful’.
New technology offers some relief. Both Heathrow and Gatwick have moved to systems that continuously calculate spacing times between incoming aircraft based on wind speeds and aircraft types, rather than mandating fixed minimum distances. NATS says this has improved landing rates and reduced delays by a meaningful margin in high winds.
Clear-air turbulence, invisible to the naked eye and impossible to detect on radar, is a separate and growing concern. Paul Williams, a professor of atmospheric science at the University of Reading, says incidents over the North Atlantic have increased by 55% since 1979, and warns that projections point to a doubling, trebling ‘or worse’ in severe turbulence on many busy flight routes. He remains confident that improvements to forecasting and laser-based detection technology can help address the problem.
Rising sea levels add a longer-term dimension to the challenge. Research by Newcastle University has identified 269 airports around the world already at risk of flooding, with that number expected to grow. Among those highlighted as potentially exposed are Amsterdam Schiphol, London City, Bahrain International and Newark Liberty International. Protecting airports against rising flood risk over the next century could cost up to $57bn, according to the Newcastle study. Gatwick, which experienced severe flooding over Christmas 2013, has spent tens of millions of pounds on mitigation in recent years, though those sums are modest beside the more than £2bn it expects to invest in its current expansion plans.
The aviation industry already faces criticism for its contribution to climate change, and it has committed to reaching carbon neutrality by 2050 while anticipating a doubling of the global aircraft fleet over the next two decades. Managing the physical consequences of a warming world, on top of that decarbonisation challenge, will test the industry’s capacity for adaptation well before that deadline arrives.
