According to a groundbreaking study published on 10 February 2015, transatlantic aviation is the latest in a growing number of sectors that needs to confront the reality of climate change. The effects of aviation on climate change have been known for some time through greenhouse emissions and contrails. A study by Paul Williams from the Department of Meteorology at the University of Reading UK is one of the first to indicate that climate change will have important consequences for aviation. Williams’ study, entitled ‘Transatlantic flight times and climate change’, examines how flight times and routes between Heathrow airport in London and John F Kennedy Airport in New York change when the atmospheric carbon dioxide (CO2) concentration is doubled.
At ground level, warmer air reduces the lift force on the wings of departing aircraft. As a consequence, it is likely that take-off weight restrictions may be more stringent in the future. Clear air turbulence is increasing in the lower stratosphere (approximately 10 kilometres or 33,000 feet above the earth’s surface) due to wind shears that are destabilising the atmosphere at these levels. Turbulence in this part of the atmosphere is a significant issue as 33,000 feet is a common cruising altitude and can cause discomfort for passengers. This discomfort can be particularly severe if turbulence is a frequent occurrence during a flight.
Using wind fields generated from climate model simulations which were fed into an operational flight path algorithm used by flight planners, Williams reported that stronger jet stream winds makes eastbound flights (from New York to London) shorter (under 5.5 hours) and westbound flights (from London to New York) longer (7 hours) all year round. Therefore, round trip journey times increase. The largest increase in round trip times is expected in autumn, with the smallest increase expected in spring and summer.
Extrapolating his results to all transatlantic flights and even without any growth in the number of these flights, Williams reports that aircraft will spend an extra 2200 hours in the air, burn an extra 7.2 million gallons of fuel, and emit an extra 70,000 tonnes of carbon dioxide each year. These figures are based on 300 round trips per day, at a fuel cost of US$3 per gallon and a carbon dioxide emission rate of 9.6 kg per gallon.
The route flown between two airports that minimises the total distance travelled is known as the ‘great circle’, which is the spherical (the shape of the earth) equivalent of a straight line. Aircraft deviate from the great circle to benefit from tailwinds (behind them) or to avoid headwinds (in front of them) and therefore minimise the flight time. The North Atlantic flight corridor between Europe and North America is one of the busiest flight paths in the world. Approximately 600 flights cross this corridor each day. Williams’ results reveal that the probability of eastbound (from New York to London) flight times less than 5.5 hours more than doubles as the carbon dioxide concentration doubles.
The current record for the shortest flight time between New York and London is 5 hours and 16 minutes on 8 January last year. This time was achieved thanks to an unusually strong tailwind from an unusually fast jet stream. Williams reports that record flight times such as this may become more common, however he also reports that the likelihood of flight times of more than 7 hours from London to New York will double as a result of having to fly into strong headwinds, and therefore delayed arrivals in North America will become increasingly common.
I must admit to finding the basis of Williams’ study and his results very intriguing. My first thought is whether the cost of transatlantic flights will increase. I would think the logical answer would be yes, given the cost of increased fuel consumption reported by Williams even without an increase in the number of flights. I can’t imagine airlines would be keen to absorb such a cost. I would be very interested in the results of a study on flights out of any Australian International airport given the number of tourists visiting Australia each year and Australia’s isolation relative to other nations.
The aviation industry must grapple with the realities of climate change and face its challenges
The ‘Transatlantic flight times and climate change’ study clearly shows that like a growing number of other sectors, the aviation industry must grapple with the realities of climate change and face its challenges. Flight times, fuel consumption and take-off weights are obviously some of the important factors that will require airlines’ critical attention. On the basis of Williams’ work, these factors are increasing crucial to their business model. The increases reported by Williams may even force a rethink of airline operations given that, like many global corporations, airlines are answerable to employees and shareholders. There is little point denying that flights are an important part of human business, personal interactions and recreation. Equally there is little point denying that climate change is already exerting an influence on many other aspects of life on a global scale. Thus it is important for Governments and citizens alike to play their respective parts in fighting global climate changes so we can continue to spread our wings.