News

A new international scientific study, with the participation of Professor Spyridon Rapsomanikis, Head of the Environmental and Networking Technologies and Applications Unit at the Athena Research Center, highlights a lesser-known but significant impact of climate change: the increase of aircraft noise around airports.

 

The study was published in the international scientific journal Aerospace (MDPI) and examines how rising temperatures affect the lift and climb angle of aircraft, leading to higher noise levels near populated areas.

This research sheds light on yet another dimension of climate change, one that goes beyond extreme weather events or sea-level rise and directly affects the quality of life around airports.

 

The warmer air resulting from climate change reduces the lift force on a departing aircraft, potentially reducing its climb angle and causing more engine noise near the airport. Here, we study this phenomenon at a selection of 30 European airports in northern hemisphere summer (June–July–August). We first formulate and verify a low-complexity model of noise propagation around airports, although we emphasise that our high-level results do not explicitly depend on this agreement. The model includes anisotropic noise propagation, atmospheric absorption, and the ability to model the noise emissions from multiple engines. We study the Airbus A320, but the method could be straightforwardly generalised to other aircraft. We refer to the model as an emulator since (using Latin hypercube parameter sampling) it mimics a more comprehensive model against which it is verified. The model is used to calculate the area enclosed by the 50 dB SPL (sound pressure level) contour, A50, which agrees well with a similar metric (using the day–evening–night sound level, Lden) from the verification target, A. Using temperature and pressure data from IPCC simulations of future climate, and using a straightforward relation between climb angle and air density, we assess how climate change could affect climb angles by mid-century (2035–2064). The value of A50 is obtained by efficiently covarying (1) the engine noise at 10 m from the engines and (2) the climb angle under ‘historical’ conditions (1985–2014). The median values (across 10 climate models) of climb angle reduction in the future warmer climate are around 1–3% (depending on the airport and climate model used), but individual days can show values as high as 7.5% for the most extreme warming scenarios. By considering the variation in the absorption coefficient of the air with frequency, we find that the number of people affected by noise pollution could increase by up to 4%—as much as 2500 people for the most highly populated areas—by mid-century and that these changes are maximized for the most damaging and psychologically ‘annoying’ (low) frequencies.

 

* Correspondence: j.h.t.williams@reading.ac.uk