Flyers might have to face more disruption with hotter skies

While the immediate sweltering conditions in the UK have since subsided, and the memory of that weekend’s travel nightmares may begin to fade for many passengers, a significant segment within the aviation industry views the June incident not as an isolated misfortune, but as a potent and alarming harbinger of future challenges. The timing of the storms was undeniably unlucky, occurring at a critical juncture for summer travel. However, a deeper concern persists: such widespread disruptions are projected to become increasingly frequent and severe as the escalating effects of global climate change destabilize weather systems worldwide. This instability, experts warn, will inevitably lead to more frequent and intense disruptions, imposing substantial additional costs on airlines, airport operators, and, ultimately, the travelling public.

Tim Atkinson, an experienced airline risk consultant and former pilot, highlights the acute vulnerability of the UK and northern Europe due to their exceptionally crowded airspace. He posits a tangible risk that all of London’s major airports – Heathrow, Gatwick, Luton, and Stansted – could simultaneously be impacted by severe storms. Such a scenario, he argues, would precipitate major consequences both in the air and on the ground, dwarfing the June incident. "What we’re witnessing now is extraordinarily rapid climate change," Atkinson explains. "We’re transitioning from weather activity that might temporarily incapacitate a single airport, which the system can generally absorb, to a situation where, with very little advance warning, it would be entirely possible to lose all of London’s airports from real-time operational capacity quite swiftly." He believes such an event would render the June disruption minor by comparison and could, disturbingly, even imperil lives. The question of its likelihood, however, remains a subject of intense debate.

At the National Air Traffic Services’s (NATS) main control centre in Swanwick, Hampshire, the threat of thunderstorms is a perpetual preoccupation. During a recent visit on a hot and humid day, ominous dark clouds loomed, and heavy, thundery downpours were already affecting the surrounding region. Within Terminal Control, the operational hub responsible for managing all flights entering or departing London and southern England, these volatile storm cells are subject to continuous, meticulous monitoring. Their progress is tracked relentlessly on large radar screens, complemented by the rigorous scrutiny of real-time weather forecasts. Air traffic typically flows in predictable waves throughout the day. At lunchtime, the activity was relatively subdued, and the storms had yet to directly impede major flight paths. Nevertheless, with a significant intensification of activity anticipated for the afternoon, NATS staff were already engaged in extensive preparations for what was expected to be a highly challenging period.

Stormy weather inherently diminishes the available airspace, compelling air traffic controllers to restrict and reroute flights, leading to inevitable delays and cancellations. For instance, if high winds or heavy rainfall render an airport’s runways unsafe for landing, incoming aircraft must be diverted to alternative airfields. This, however, introduces a cascade of new problems. If too many unscheduled aircraft converge on an already busy airport, its existing infrastructure may be insufficient to accommodate them all. Planes require adequate fuel, parking stands, and maintenance facilities. Passengers, meanwhile, need food, water, and access to ground transportation. In extreme cases, an airport might be forced to refuse all but emergency traffic if its capacity is overwhelmed.

This is precisely where Atkinson’s dire scenario takes hold. He warns of a situation where simultaneous diversions from Heathrow, Gatwick, Luton, and Stansted would leave a multitude of aircraft, including those arriving across the Atlantic and a substantial volume of European flights, all desperately searching for an available landing strip, some with critically dwindling fuel reserves. This would, at the very least, inflict monumental disruption upon passengers, who might find themselves hundreds of miles from their intended destinations with no immediate means of onward travel. More gravely, Atkinson fears it could escalate into "a very serious risk event, such as an aircraft running out of fuel in the sky." While aircraft are legally mandated to carry enough fuel to reach an alternative airport plus an additional 30 minutes of flying time, extreme, unforeseen delays could push these margins to their limits.

Not everyone within the industry shares Atkinson’s extreme level of concern. Andrew Charlton, a former airline executive and managing director of the Swiss-based consultancy Aviation Advocacy, acknowledges the importance of considering worst-case scenarios but urges a balanced perspective. "You’ve always got to imagine the worst-case scenario," Charlton concedes, "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… of all the things that wake me up at 3 am… this is not the top of that list." He emphasizes the robust safety protocols and experienced decision-making within the aviation sector.

Thunderstorms are fundamentally products of what meteorologists term convective activity. This process occurs when moist air near the Earth’s surface warms rapidly and ascends quickly into the atmosphere. As this air rises, it expands and cools, causing the moisture it carries to condense and form the distinctive, towering cumulonimbus clouds associated with storms. The key link to climate change is straightforward: more atmospheric heat translates directly into more convective energy, significantly increasing the potential for atmospheric instability. Furthermore, for every degree Celsius the Earth’s temperature rises, the atmosphere gains the capacity to hold approximately 7% more moisture, dramatically elevating the probability of heavy rainfall during storm events.

While it remains uncertain whether these conditions will lead to an overall increase in the number of thunderstorms across the UK and Europe, given the myriad variables involved beyond simple energy and moisture, studies strongly suggest that higher latitudes, particularly in the northern hemisphere, will experience the most significant increases in conditions conducive to storm formation. Crucially, the storms that do form are expected to be considerably more violent and impactful. According to the UK’s Met Office, "while we may not see more thunderstorms overall, the ones we do experience could be more impactful."

Pilots, prioritizing safety above all else, will always endeavor to avoid flying through convective weather. Even though modern aircraft are engineered to withstand severe atmospheric conditions, thunderstorms can generate exceptionally intense turbulence, capable of inflicting structural damage to the airframe and violently throwing unbelted passengers and crew around the cabin. Hail, often an accompanying feature of severe storms, poses another grave threat, with the potential to crack windscreens, damage engine components, and compromise flight control surfaces. Thus, regardless of the inconvenience to passengers, flight crews will invariably choose diversion or delay over risking safety.

Current onboard weather radars provide aircrew with visibility up to 320 nautical miles ahead, complemented by access to live online weather forecasting resources. However, thunderstorms are notoriously fast-moving and unpredictable. Professor Guy Gratton, an expert in aeronautics at Cranfield University, notes that these systems are essentially "tactical rather than strategic." While they enable pilots to detect storm cells on their screens from a relatively short distance and request immediate diversions, they do not facilitate comprehensive long-distance planning. This limitation often results in unplanned diversions occurring late in a flight, inevitably leading to increased fuel consumption. Should storm-related delays become more prevalent, Andrew Charlton anticipates that aircraft will be compelled to load more fuel as a standard precaution against unforeseen weather disruptions. "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 states. Given that fuel represents one of an airline’s most substantial operating costs, any increase in the fuel bill will, Charlton asserts, inevitably be passed on to passengers through higher fares.

The prospect of more intense storms also exacerbates the complexity of air traffic management in already busy regions, inevitably leading to more frequent delays and cancellations. Nevertheless, advancements in technology offer some avenues for mitigation. Both Heathrow and Gatwick airports, for example, have transitioned from rigid minimum distance mandates between incoming aircraft to a dynamic system that continuously calculates optimal spacing times based on real-time wind speeds and aircraft types. This innovative approach aims to enable controllers to safely reduce the separation between landing aircraft, especially during high winds, thereby accelerating their touchdown rates. NATS reports that this system has successfully improved landing rates and significantly reduced delays.

Beyond airborne disruptions, severe storms bring the heightened risk of heavy rainfall and subsequent flooding. In extreme scenarios, this can completely paralyse airport operations, as vividly demonstrated in April 2024 when torrential downpours deluged Dubai International Airport. The runways were briefly forced to close, and the ensuing disruption persisted for two full days, leading to the cancellation of over 1,200 flights and impacting tens of thousands of passengers. Even if runways and taxiways remain clear, and aircraft can operate without impediment, passengers may face insurmountable difficulties reaching their flights if access roads, railway lines, or airport car parks are inundated. Protecting against such pervasive risks demands substantial financial investment. Gatwick Airport, having experienced severe flooding during the Christmas period in 2013, has since invested tens of millions of pounds in comprehensive mitigation strategies. However, these figures are dwarfed by the more than £2 billion it plans to allocate for its current expansion projects, highlighting the scale of necessary resilience building.

The insidious problem of clear-air turbulence also represents a growing threat. This phenomenon, which cannot be visually detected and occurs in seemingly clear skies, is becoming increasingly common as the global climate warms. It involves violent air movements at high altitudes without the presence of clouds or other visual cues that would allow pilots to anticipate and avoid it. While often resulting in minor bumpiness for passengers, it can occasionally be far more severe. A striking example occurred on March 1, 2023, when a Lufthansa flight from Austin, Texas, to Frankfurt encountered what the airline described as "brief but severe" turbulence. Eyewitness accounts from aboard the aircraft detailed how passengers and flight crew were violently thrown around the cabin as the plane suddenly lost altitude. Following an emergency landing in Washington D.C., seven individuals required hospitalization. Though still rare, this type of turbulence is already significantly more prevalent than in previous decades and is projected to intensify further. Paul Williams, a professor of atmospheric science at the University of Reading, warns that "the projections are pretty dire: doubling, trebling or worse in the amount of severe turbulence on many busy flight routes around the world." He notes that incidents over the North Atlantic have increased by 55% since 1979. Nevertheless, he expresses confidence that solutions, including enhanced forecasting and the deployment of laser-based detection technology, can be developed.

Another profound climate-related threat to aviation, which may prove exceedingly challenging to surmount, is rising sea levels. When Hurricane Sandy struck the US East Coast in October 2012, its powerful storm surge inundated vast swathes of New York City. The two runways at New York’s LaGuardia Airport were submerged for several days, rendering the airport inoperable even after the hurricane’s winds had subsided. Significant flooding events in the New York City area, which would have occurred once every 500 years in pre-industrial times, are now experienced approximately every 25 years. Projections from one major study suggest these events could occur as frequently as every five years by the middle of the century, rendering LaGuardia, which is built on reclaimed land adjacent to Flushing Bay, highly vulnerable.

LaGuardia is not an isolated case. With nearly 40% of the world’s population residing within 100 kilometers of coastlines, a considerable number of airports globally have been constructed on low-lying coastal areas. Research conducted by Newcastle University indicates that 269 airports worldwide are already at risk of flooding due to rising sea levels, a figure that is expected to increase substantially. Among those potentially most exposed are major international hubs such as Amsterdam Schiphol, London City, Bahrain International, and Newark Liberty International. Many airports currently possess some degree of flood protection, particularly larger ones. However, effectively countering the escalating flood risks over the coming century will necessitate expensive investment in robust flood defenses, the costly raising of runways, or even the radical relocation of entire airport facilities. The Newcastle report estimates these adaptation costs could reach up to $57 billion (£42 billion). Such monumental expenses are ultimately likely to be borne by taxpayers or directly by travellers through increased fees and fares.

The aviation industry frequently faces criticism for its own substantial contribution to global climate change emissions. It confronts a formidable, dual challenge: striving to achieve carbon neutrality by 2050 while simultaneously accommodating projected growth that anticipates a doubling of the global aircraft fleet within the next two decades. Yet, it is unequivocally clear that the profound impacts of climate change will not only be influenced by the industry but will also be acutely felt by airlines, airports, and, inevitably, by the millions of passengers who rely on air travel. "I think the best we can do is mitigate," concludes Andrew Charlton. "We need to ensure we have enough space at air terminals for people whose flights are being disrupted and delayed, that we have enough hotel rooms and parking space and so on." Ultimately, he contends, "disagreeable moments are going to happen more." Passengers, he believes, will simply have to accept this as an unavoidable reality of modern air travel.