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Impacts of Aviation on the Climate

Led by Professor David Lee, this Research Group investigates the global-scale emissions of aviation and their impacts upon climate. The Group is currently working on a range of projects (hyperlink to 8.3 current projects) for a number of UK Government Departments and the European Commission using a range of in-house modeling tools  to calculate global aviation emissions and scenarios, chemical impacts at a variety of scales, contrail coverage and simplified climate response models of aviation specific effects. This research enables CATE to provide advice and technical support on climate change issues that relate to aviation for UK Government Departments and supports their technical inputs to the International Civil Aviation Organization (ICAO) and the United Nations Framework Convention on Climate Change (UNFCCC)

The Centre for Aviation, Transport, and the Environment (CATE) – the responsible research unit within MMU – has a unique position at the interface of both science and policy research of aviation and climate impacts. We undertake world-class research, play major management roles in related European research programmes, have provided Lead Authorship input into the reports of the Intergovernmental Panel on Climate Change (IPCC), and acted as Scientific Focal Point to CAEP and Rapporteurship on Aviation and the Environment to the World Meteorological Organization.

Why Research Aviation and Climate Change?

Aviation represents a major contributor to the UK and global economy. The industry has grown strongly over the past decades and at a global rate of 5.3% per year (in Revenue Passenger Kilometres – RPK) between 2000 and 2007, despite various world-changing events and industry difficulties over the period. This growth has resulted in a commensurate growth in fuel usage and therefore CO2 emissions (Figure 1). In addition, there are a number of non-CO2 effects that impact on climate from, e.g. emissions of NOx, particles, water vapour etc. resulting in secondary effects such as formation of tropospheric ozone (O3), destruction of ambient methane (CH4) and formation of contrails and aviation-induced cirrus clouds (AIC). Thus, whilst representing a major wealth-provider, aviation needs also to be cognisant of and combat its harmful effects on the environment and climate.

 Figure 1. Growth of aviation in RPK over time and corresponding fuel usage and CO2 emissions, in relation to other sources (source: Lee et al., 2009a).


Whilst the recent economic downturn has had the effect of decreasing growth rates, the longer-term perspective is that growth will continue to increase to 2050. This means that continued efforts need to be made to mitigate aviation’s emissions, since growth rates are outstripping rates of technological improvement.

Similar growth rates for UK aviation are expected out to 2050, as recently assessed by the UK Committee on Climate Change. The UKCCC report also highlighted that such growth could represent a significant fraction of UK CO2 emissions, should aviation be included in the UK CO2 emissions targets to 2050, which could put compliance with UK targets at best under severe pressure or at worst, failing to meet them. Moreover, the UKCCC also pointed out the additional effects of non-CO2 emissions, reproducing a figure from an MMU peer-reviewed paper (Lee et al., 2009a, see Figure 2).

Figure 2. Radiative forcing effects from aviation in 2050, reproduced from Lee et al. (2009a), from DfT-funded research at MMU.

Our Aviation and Climate Change Research Programme

Understanding non-CO2 effects of aviation on climate has been a major component of work of CATE on behalf of the UK DfT and from MMU’s participation in all the key European research projects dealing with this topic, such as ‘ATTICA’, ‘QUANTIFY’, ‘ECATS’ and ‘REACT4C’ (hyperlink to projects) . The output from ATTICA was a major peer-reviewed assessment of aviation effects on climate, MMU leading a prestigious global-authorship team, recently published in the journal ‘Atmospheric Environment’ (hyperlink to reference Lee et al., 2009b). This paper, amongst many other things, produced the first authoritative data-based assessment of a CO2 emissions multiplier (using a net Global Warming Potential of 100 years’ time-horizon), a subject which has vexed both scientific and regulatory communities since the landmark IPCC aviation report (IPCC, 1999). Nonetheless, the ATTICA assessment warned that although a multiplier was now available, care should be taken over its use, and that it had a high level of scientific uncertainty.