Private aviation is making a growing contribution to climate change

The research question addresses the quantification of private aviation's contribution to climate change, a sector whose impact is not well understood despite the known growing emissions from commercial aviation. The study's purpose is to provide a comprehensive assessment of private aviation's CO₂ emissions using large-scale flight tracker data. This is crucial because while the climate impact of commercial aviation is increasingly acknowledged, the role of private aviation remains under-researched. Understanding this impact is important for effective climate policy design and mitigation strategies. The significance of the study lies in its potential to inform policies targeted at reducing emissions from this high-impact, high-growth sector. Previous studies have provided limited estimates, focusing on specific regions or smaller datasets, thus necessitating a global, comprehensive analysis. This research fills a critical gap by providing a detailed analysis of the energy intensity, global distribution, and travel patterns of private aviation, offering a more complete picture of its environmental footprint.

Existing literature acknowledges the significant and growing contribution of commercial aviation to climate change, estimating CO₂ emissions in the range of 892-936 Mt in 2019, representing approximately 4% of global anthropogenic effective radiative forcing. Studies highlight the disproportionate impact of frequent flyers and premium class travel on overall emissions. However, research on private aviation's role remains fragmented. Some studies evaluated limited numbers of private jets or focused on specific geographical areas like the USA, providing incomplete assessments of the sector's global scale and emissions. The lack of comprehensive data and the challenges in accessing private flight information have hampered a more complete understanding of the sector’s environmental impact. This study aims to overcome these limitations by leveraging a large, global dataset to analyze private aviation's contribution to climate change.

The study utilizes flight tracker data from the ADS-B Exchange platform for the period 2019 to 2023. The dataset encompasses 25,993 private aircraft and 18,655,789 individual flights. Flight times were linked to 72 aircraft models and their average fuel consumption values to calculate CO₂ emissions. The methodology involved several steps: 1. **Data Acquisition:** The researchers retrieved the entire database for private aircraft from ADS-B Exchange, amounting to 1.8 terabytes of data. This platform provides comprehensive and unfiltered traffic data, enhancing the accuracy of the analysis. 2. **Aircraft Model Inclusion:** Flight data were matched with 72 aircraft models and their respective fuel consumption values (in g CO₂ equivalent per hour) obtained from marketing materials. This enabled precise calculation of emissions based on the flight time of each aircraft. 3. **Emission Calculation:** CO₂ emissions were calculated by multiplying the fuel consumption (in gallons per hour) by conversion factors to obtain kilograms of CO₂ emitted per hour. This calculation considered the flight duration for each leg of the flight. 4. **Data limitations:** The analysis acknowledged limitations in the data. Flights under the Federal Aviation Administration's ADS-B Privacy program (using Privacy ICAO Addresses) were excluded, potentially leading to an underestimation of emissions. The methodology also accounted for potential signal losses and coverage limitations of the ADS-B Exchange data. 5. **Spatial Pattern Analysis:** Spatial patterns of private aviation were analyzed to understand the importance of global events and their impact on air travel. Global events like the World Economic Forum, Super Bowl, COP28, and Cannes Film Festival were examined. The analysis identified the most frequented destinations and the geographic distribution of private aviation activity. Further analysis focused on flight patterns and frequency in relation to seasonal trends and days of the week, highlighting the prevalence of leisure travel. The researchers also employed a bootstrapping method for assessing the accuracy of distance and emissions estimates, providing confidence intervals to quantify uncertainties.

The study's key findings are as follows: 1. **Significant CO₂ Emissions:** Private aviation contributed at least 15.6 Mt of CO₂ in direct emissions in 2023, representing a substantial contribution to climate change. This translates to an average of 3.6 t CO₂ per flight, highlighting the high energy intensity of this mode of transport. 2. **High Concentration in the USA:** The USA accounts for a disproportionately large share (68.7%) of all private aircraft registered globally, despite having only around 4% of the world's population. This reflects the concentration of wealth and private aviation usage in the country. 3. **High Energy Intensity:** The study confirms that private aviation is an extremely energy-intensive mode of transportation, some aircraft models producing CO₂ emissions per hour greater than an average human’s annual emissions. Aircraft frequently operate at high altitudes which may further exacerbate their contribution to non-CO2 radiative forcing. 4. **Dominance of Short Flights:** A significant proportion (47.4%) of private flights are relatively short (less than 500 km), suggesting a high proportion of flights used for leisure or shorter business trips, thus adding to the overall emissions given the energy intensive nature of these shorter trips. 5. **Events as Emission Drivers:** Major global events significantly increase private aviation activity, attracting substantial numbers of flights and generating considerable CO₂ emissions. This illustrates the impact of events as a source of emissions. 6. **Leisure Travel Dominance:** The analysis shows a clear seasonal trend and concentration on weekends, indicating that private aviation is frequently used for leisure purposes. 7. **Growth Trends:** Emissions from private aviation grew by 46% between 2019 and 2023, considerably outpacing the efficiency improvements observed during the same period. Industry projections anticipate continued growth in the sector, suggesting a further increase in emissions in the coming years. 8. **Concentration of Air Travel:** The study showed a high concentration of private air travel in certain countries, most prominently the USA and specific locations such as Miami. This highlights the need for targeted policy interventions. 9. **Public Figures' Travel:** An analysis of the flight patterns of global public figures revealed high flight frequencies and distances covered, further highlighting the substantial contribution of private aviation to emissions from high-emitting individuals.

The findings underscore the substantial and growing contribution of private aviation to climate change. The high concentration of private aircraft in the USA, the prevalence of short flights for leisure purposes, and the strong correlation with large-scale events all contribute to the sector's significant environmental impact. The substantial growth in emissions, exceeding improvements in fuel efficiency, indicates a need for urgent intervention. These findings have several important implications. The high energy intensity and considerable emissions per flight, even for short distances, suggest that targeting short flights and leisure travel could significantly decrease the overall impact. The analysis highlights the need for regulations and policies to curb emissions in the private aviation sector, possibly similar to those employed in the commercial aviation industry (demand and supply-side management). The concentration of private aviation use among high-net-worth individuals raises questions about the role of wealth and consumption patterns in climate change. Addressing this sector's impact would also require addressing larger societal issues related to sustainable consumption and inequality in emissions.

This study offers a comprehensive assessment of the global scale, distribution, and environmental impact of private aviation, highlighting its significant and growing contribution to climate change. The high emissions per flight, concentration in specific regions, and strong association with leisure and major events emphasize the urgency for effective regulatory intervention. Future research could further investigate the non-CO₂ climate impacts of private aviation, explore the potential of sustainable aviation fuels in this sector, and examine the effectiveness of different policy instruments in mitigating emissions from this high-impact group.

The study acknowledges several limitations that may affect the interpretation of its findings: The exclusion of flights using Privacy ICAO Addresses (PIAs) leads to a potential underestimation of emissions. Signal losses and coverage limitations inherent in ADS-B data could also influence the accuracy of the results. The use of average fuel consumption values, instead of flight-specific data, introduces a level of uncertainty in the calculations. Finally, the study only examines direct emissions from fuel use during flight, excluding emissions from taxiing, ground operations, and the aircraft lifecycle.