Climate Prediction: “Take-off distances will get longer as the climate warms”

Guest essay by Eric Worrall

Climate Scientists predict Global Warming will be bad for air travel – but their claims ignore human adaption.

Climate change means longer take-offs and fewer passengers per aeroplane – new study

February 14, 2020 2.23am AEDT

Guy Gratton Associate Professor of Aviation and the Environment, Cranfield University

Paul D Williams Professor of Atmospheric Science, University of Reading

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As the local climates at airports around the world have changed in the past few decades, the conditions that pilots have relied on in order to take off safely have changed too. Our new research suggests that higher temperatures and weaker winds are making take-off more difficult. In the long run, this means that airlines are delivering fewer passengers and cargo for the same amount of fuel.

“Climate” essentially means the average weather conditions at any given place. Scientists know this is changing, but not uniformly. While global temperatures have risen by about 1°C on average, some places have warmed by much more already – and others may be getting cooler.

But climate change isn’t just about temperature – winds are slowing down and changing direction around the world too. This is a problem for airport runways that were built many years ago to align with the prevailing winds at the time. 

Research has predicted that take-off distances will get longer as the climate warms. This is because higher temperatures reduce air density, which the wings and engines need to get airborne. With reduced headwinds, aeroplanes also need to generate more groundspeed just to get into the air. Once they’re up there, they’re subject to in-flight turbulence, which is getting worse due to climate change increasing the energy in jet stream winds. 

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That could mean that airlines must reduce the numbers of passengers they carry on flights, or search for ways to lengthen their runways. In some extreme cases, it could become impossible for some aeroplanes to use some airports altogether. This is another reminder of how rapidly and extensively human actions are transforming the world around us, and how ill equipped we are to deal with the consequences.

Read more: https://theconversation.com/climate-change-means-longer-take-offs-and-fewer-passengers-per-aeroplane-new-study-131613

The abstract of the author’s study;

The impacts of climate change on Greek airports

Guy Gratton, Anil Padhra, Spyridon Rapsomanikis, Paul D. Williams
First Online: 13 February 2020

Time series of meteorological parameters at ten Greek airports since 1955 indicated the level of climate change in the Eastern Mediterranean area. Using this data, take-off performance was analysed for the DHC-8-400—a typical short range turboprop airliner, and the A320, a typical medium scale turbofan airliner. For airports with longer runways, a steady but unimportant increase in take-off distances was found. For airports with shorter runways, the results indicate a steady reduction in available payload. At the most extreme case, results show that for an Airbus A320, operating from the, relatively short, 1511m runway at Chios Airport, the required reduction in payload would be equivalent to 38 passengers with their luggage, or fuel for 700 nautical miles (1300 km) per flight, for the period between the A320’s entry to service in 1988 and 2017. These results indicate that for airports where aeroplane maximum take-off mass is a performance limited function of runway length, and where minimum temperatures have increased and/or mean headwind components decreased, climate change has already had a marked impact on the economic activity in the airline industry. Similar analyses could be usefully carried out for other runway-length–limited airports, which may often include island airports. It is also noted that previous research has only considered temperature effects, and not wind effects. Wind effects in this study are less significant than temperature, but nonetheless have an effect on both field performance noise and pollution nuisance around airports.

Read more: https://link.springer.com/article/10.1007%2Fs10584-019-02634-z

Why am I disputing the predictions of a professor of aviation?

For starters, the body of their study expresses a lot less certainty that anthropogenic climate change is responsible for the observed changes than is suggested by the press release. From body of the main study;

In Greece, in particular, the wind speed at 20 measurement sites at a height of 2 m has decreased over the period 1959–2001, consistent with our findings at airports. A possible explanation for these wind trends is that anthropogenic climate change is warming the poles faster than the tropics in the lower atmosphere, weakening the mid-latitude north-south temperature difference and consequently reducing the thermal wind at low altitudes (Lee et al. 2019). Another possible explanation is that anthropogenic climate change is expanding the Hadley cells, pushing the fast winds associated with the storm tracks towards the poles and away from the midlatitude regions. A final possible explanation is an increase in surface roughness, caused by an increase in vegetation or (in our case) development around the airports.

Read more: Same link as above

I have personal experience flying an aircraft. “Surface roughness” has a huge impact on low altitude wind speed. “Surface roughness” should have been their first theory, not wild speculation about Hadley Cells or reduced latitudinal temperature differences, especially given recent observational evidence that away from “surface roughness”, global windspeed is actually increasing.

Urban heat island from all that development might also explain much of the observed rise in temperature at the airports in the study.

What about the other points the professors make? Their calculation of the impact of wind speed and temperature on aircraft performance look reasonable, temperature and wind speed do have a significant effect on aircraft.

But the authors of the press release did not explain that their study ignores human adaption to changed circumstances.

If local warming at the airports and reduced wind speed does start to have a significant impact on the ability of aircraft to operate in some regions, aviation companies will not simply abandon profitable routes whose airfields which are causing them operational difficulties. Aircraft manufacturers will respond to new requirements by upgrading the aircraft; by modifying the engines to deliver more thrust on takeoff, or by adjusting aircraft wings to provide greater lift for difficult takeoffs.