Turbulent Times

Around the world, airports areseeing severe weather not typical of their regions. Record rains and snowstorms have hit the US east coast, dust storms have engulfed the Australian capital Sydney and the Arizona city of Phoenix; blizzards have brought London’s Heathrow to a standstill; while floods, tornados and extreme temperatures have swept Australia and New Zealand.

Climate change is now a widely accepted fact—even though the timings and causes are disputed. For airline and airport operators, the big question is the potential impact on services. For instance, do airports that previously almost never saw snow have to start thinking about stocking more plows and de-icing equipment?

“Ten years ago the question of whether or not climate was changing was a hot political—and to some degree—scientific debate,” said Peter P. Neilley, vice president of Global Forecasting Services for The Weather Channel Companies. “For the most part, today we’ve moved beyond that debate.” The political debate today centers on whether the phenomenon is man-made, and the vast majority of scientists are convinced it is, Neilly said.

So while much has been written and discussed about the impact of aviation on the climate, little had been done to better understand climate change’s potential effect on aviation. Now, there’s a surge of research. “In the last five years or so . . . we have begun measuring changes in the climate as opposed to just forecasting them,” said Neilley, who also chairs the American Meteorological Society’s Weather Analysis and Forecasting committee.

Consensus among scientists is that temperatures will rise two to five degrees Celsius over the next 50 years, but these changes alone would have little impact on aviation. Some desert-based airports, for example, regularly experience 40 degree Celsius days (104 Fahrenheit). But high temperatures do impact aircraft performance and mean more weight restrictions: fewer passengers, less cargo equals less revenue.

“Those would be where you would expect to see changes if you were talking about global change purely as a global warming story,” Neilley said.

In their paper Climate Variability and Change with Implications for Transportation, four more US National Oceanic and Atmospheric Administration (NOAA) scientists teamed with a colleague from the US Department of Energy’s Lawrence Berkeley National Laboratory to study the extent of potential effects on airport and airline operations with the anticipated rise in global temperatures. “On hot summer days at high-altitude airports such as Denver International, aircraft may have to burn fuel, unloading weight, in order to have a safe take-off roll,” the researchers say. “For aircraft that use up most of the pavement on even the longest runways, even a one or two percent increase in density altitude from increased moisture may put those aircraft out of commission for daytime operations on certain days.”

That’s the temperature-pegged primary effect of global warming: higher temperatures. But Neilley argues it’s not the most important impact. There’s a secondaryeffect.  And it’s this secondary effect that has the potential to pack the most potent operational punch: the atmosphere is becoming more volatile. Hurricanes, thunderstorms, sandstorms and severe winter storms are the manifestations of this warmer, more volatile atmosphere. Neilley believes that severe weather events are perhaps becoming not only more frequent, but also more intense.

This is where the climate debate meets the reality of day-to-day airline operations. And while planetary temperatures may take 50 years to increase by the predicted two to five degrees Celsius, Neilley believes the fall-out in terms of more frequent severe weather will be seen much sooner. Between now and 2030, he says disruptive weather, the kind sufficient to force major airline operations changes and rescheduling, may double. Hardest hit, Neilley believes, will be the non-tropical, northern latitude regions in Europe and North America.

On the face of it, air-traffic-crippling 2009/2010 winter storms in Washington, D.C. and New York, and 2010 blizzard onslaughts in Western Europe, argue against global warming. “People . . . naturally think, ‘well, the temperature is going up, therefore there’s going to be less snow and freezing precipitation,’ ” Neilley said. The reality is, “If the atmosphere indeed becomes more volatile, we should be prepared to have strong winter storms.”

But what could be turning the US East Coast colder in recent winters is the North American Oscillation, or NOA, Neilley said. This is the phenomenon where the Jetstream dives south, opening up the back door for colder air to come in. “We’ve seen the propensity for this NOA pattern to occur much more often in recent years. It’s consistent with the climate change theory,” Neilley said. The Jetstream has also nosedived over Europe of late, rendering the UK and the continent colder.

For some US airlines, the impact on operations are already being noted. “We have felt the effects of an increase in the number and intensity of mid-latitude winter storms and tropical systems in recent years,” JetBlue Airways spokesperson Allison Steinberg said. Such storms “in the Washington, D.C. and New York areas in particular have driven a large number of delays and cancellations over the last couple of years.”

Southwest Airlines, however, says it has not yet seen any real evidence of major impacts. “Over the last 10 years, weather’s impact on our OTP (on-time performance) has been about 8.5 to 9.5 percent,” Steve Hozdulick, Southwest’s director of operational performance, said. “We haven’t seen that . . . change substantially over the past five or six years.”

Mitigating, perhaps even masking, weather’s effect on operations, however, has been decreased traffic in many regions around the globe (see table, Cancellations, by the Numbers). FlightStats looked at 15 major, geographically diverse airports from 2006 through 2010. In 2006, they cumulatively handled 3,196,550 operations, and racked up a 1.69% cancellation rate. In 2010, despite handling just 3,005,446 operations, the cancellation rate had risen significantly—to 2.36%.

Correlating significant weather-pattern changes with air traffic operations is also still a relatively new exercise. “We manage convective weather by using traffic management initiatives,” FAA spokesperson Paul Takemoto said. While a single year is far too short a period to correlate climate change to ATC slowdowns, he says, from May 1 through July 31, severe weather meant the agency needed to employ these techniques for a total of 543 hours, a 34.4% increase over the 378 hours for the same period the previous year. The weather patterns that spawned the air traffic slowdowns, says Takemoto, “generated above normal thunderstorm activity for the Central Plains, the Ohio Valley . . . Tennessee Valley and the Northeast when compared to a 10-year average.”

On the other side of the world, weather over the past 12 months has been so extreme that some airlines placed weather events above fuel prices as a major impact to reduced profits or losses.

Costly Weather Downunder 

The most significant impact was the severe flooding in Queensland, Australia, in January that killed over 40 and flooded more than 50,000 homes followed by the monster cyclone Yasi in February that covered an area almost the size of the continental US.

Yasi’s pre-landfall core was more than 500 km across with winds up to 300 km/hr and up to one meter of rain. Its associated activity stretched well over 2,000 km.

The impact on Virgin Australia (VA), which is based in Brisbane, was severe, both from the direct impacts of the weather events and the subsequent fall in tourism traffic. VA posted a loss of A$66.6 million ($69.75 million) for its fiscal year ended June 30 compared to a profit of A$21.3 million in the year-ago period with the airline blaming the weather events as the major cause.

Qantas said weather events in Australia, New Zealand and the UK, as well as the Japanese earthquake and Chilean volcanic ash, cost the airline A$244 million for its year ended June 30, 2011.

In New Zealand, the story is similar with the warmest May on record, devastating the opening of the ski season and impacting tourism. The warm weather remained through the end of June, which was the third warmest on record, but then the heavens opened up in July and August and the country had to deal with the most extreme snowstorms experienced in 70 years according to New Zealand’s MetService weather ambassador Bob McDavitt.

“The [August] polar blast was long lived and delivered snow to many regions of the country. While heavier snowfalls have been recorded before in some regions, this is undoubtedly the most widespread and prolonged event since 1939,” McDavitt said.

The icy blast in July and August, which essentially blanketed New Zealand, created havoc for Air New Zealand, which was forced to cancel 355 and 498 flights respectively.

May’s record warm weather is thought to have been responsible for a severe—for New Zealand—tornado that killed one and injured more than 30 people when it struck Auckland.

In Australia, Ross Garnaut’s Climate Change Review 2001 noted that new observations of a changing climate include an increase in extreme weather events.

“The Black Saturday fires in Victoria in 2009 and recent [2011] major cyclones in Queensland are both consistent with expected outcomes in a warming world, although we cannot draw conclusions about direct cause and effect,” Garnaut said. “Other studies since 2008 have confirmed that Australia is also seeing historically unprecedented periods of wet and of dry in different areas of the continent.”

In his original Climate Change work published in 2008 Garnaut said that “extreme climatic events have become immediately more intense.”

That’s an outlook that is backed up by research in Europe. In 2010, Eurocontrol scientist Tamara Pejovic, then working with the consultancy Helios, presented a paper at the International Air Safety & Climate Change Conference in Cologne. Implications of Climate Change on Air Transport – A UK Case Studyindicates “Possibly more severe weather patterns” could be in store: More intense rainfall, frequent thunderstorms, and altered wind patterns. These could mean reduced safety margins and efficiency, decreased runway capacity and, of course, costly airspace and airport closures.” Pejovic specifically explores the potential consequences at London Heathrow, where projections show a one-hour closure would cost between €700,000 and €1.25 million ($950,000–$1.7 million).

 “If carbon costs are considered, the total cost could double.” Pejovic, now a safety and data expert at the Directorate Single Sky/Performance Review Unit, said.

Sea Change  

Temporary closures are bad enough, but with related rises in sea levels, some closures could be permanent.  NOAA’s Climate Variability and Change with Implications for Transportationreport shows that between 1993 and 2005, the rate of sea-level rise was 3mm per year—1.6 times faster than the rise that the US Intergovernmental panel on Climate Change projected for the period between 1990 and 2010. NOAA’s paper calls for a “risk analysis of specific [airports] . . . built long ago in coastal areas.” 

There are many airports around the world with an elevation at or below 22 ft. mean sea level (MSL). These are most at risk. Among the US airports NOAA identifies as at or below 22 ft. MSL are Key West International (1.2 m/4 ft.) in Florida; New Orleans International (1.8 m/6 ft.); San Francisco International (3.4 m/11 ft.); New York Kennedy (4 m/13 ft.); Washington National (4.9 m/16 ft.); and Boston Logan (6.1 m/20 ft.). Best positioned among the 20-somethings was New York LaGuardia. It perched a comparatively high 22 ft., or 6.7 m, above MSL. At or near the low end of the international totem pole is Amsterdam Schiphol. It’s 4.5 m (14.76 ft.) below MSL.

In the wake of a Hurricane Irene, which hit the US East Coast this past summer, there’s also renewed interest in climate change’s impact on coastal infrastructure. According to NOAA, The Metro New York Hurricane Transportation Study calculates a worst-case Category 3 hurricane would produce a storm surge of 21 ft., or 6.4 m: JFK’s critical field elevation is just 13 ft.

The consensus of the scientific community points to anticipated higher sea levels, more frequent and severe convective weather, and “hot and high” airfields rendered even hotter and heavier. Neilley concludes it’s time for airlines to plan for a higher frequency of weather events impacting their operations. “They should fundamentally build that into their business models,” he said.

— Geoffrey Thomas contributed to this article.