Memorandum submitted by British Airways
AIRCRAFT NON-CO2 EFFECTS
1. Further to the evidence given by British
Airways on 13 March 2007, this paper provides additional information
regarding the quantification of aircraft non-CO2 effects and applicability
to carbon offsets.
2. British Airways supports a long-term
strategy to limit air transport's climate change contribution
based on robust science, sound economics and well-developed policy
3. There are fundamental scientific barriers
in estimating the climate impact of aircraft emissions, because
of gaps in current understanding. British Airways is contributing
to research to help close these gaps.
4. Non-CO2 "multipliers" based
on the Radiative Forcing Index are a mis-application of science
because they fail to account for the resident timescales of emissions.
British Airways has commissioned a review of the techniques available
to appropriately quantify aircraft non-CO2 effects.
5. The non-CO2 effects of aircraft must
be addressed, but carbon trading and carbon offsetting are not
suitable instruments to achieve this.
6. Technological improvements, specifically
in response to demanding airport ambient air quality standards
in Europe, are currently sufficient to mitigate the effects of
NOx at altitude.
7. Like most other combustion activities,
air transport contributes to climate change through a range of
direct and indirect effects for which there is a wide range of
scientific understanding. Aircraft contribute to climate change
directly through CO2 emissions and indirectly through less well
understood effects in the atmosphere linked to NOx-induced ozone
generation, NOx-induced methane reduction and cirrus cloud formation.
8. There are fundamental scientific barriers
in estimating the climate impact of aircraft emissions, because
of gaps in current understanding. The atmospheric science community
reports that "much work [is] yet to be done before we can
have higher confidence in assessments of the impact of aviation
on climate change and establish methods by which these effects
might be ameliorated."
9. Given this range in understanding, specific
measures will be necessary for addressing specific effects, and
will need to be introduced over different timescales to allow
the necessary research to take place.
10. Quantifying the total climate impacts
of aviation remains a subject of primary research. The standard
metric used to represent climate change impacts is the Global
Warming Potential (GWP). GWP is a policy-relevant metric and takes
account of the long residence timescales of greenhouse gases defined
in the Kyoto Protocol by integrating over a 100 year period.
11. Radiative Forcing is a general atmospheric
science concept that describes any perturbation to the energy
balance of the coupled Earth-atmosphere system, for example resulting
from the release of CO2 emissions. The Radiative Forcing Index
(RFI) is the ratio between the total radiative forcing from aviation
at a given time and the radiative forcing from aviation CO2 emissions.
12. Crucially however, the use of an "RFI
multiplier is a mis-application of science as it fails to account
for the resident timescales of emissions and thus attributes a
larger fraction of climate change emissions to aircraft than is
13. If we were to apply a metric equivalent
to the Kyoto GWP to aviation climate impacts, the relevant "weighting
factor" could be around 1.2.
14. Considered from a different perspective,
if we were to apply a RFI multiplier to emissions from shipping,
an increase in shipping activity could be interpreted as being
beneficial to the climate. This would clearly be a perverse outcome,
and it demonstrates the inappropriateness of the RFI multiplier
15. However, this is not to say that a simple
"multiplier" philosophy is itself a valid approach to
developing policy to address the non-CO2 effects of aviation.
In fact, given that aviation's non-CO2 effects are not directly
related to fuel burn in the same way that CO2 emissions are, different
mechanisms will be required to address the different effects.
For example, for CO2, emissions trading and (the closely related)
carbon offsetting are valid and effective policy instruments.
But for effects that are related to altitude or location, other
mechanisms, such as technology standards or operational limitations
are likely to be more valid and effective.
16. British Airways has commissioned a review
of the techniques available to appropriately quantify aircraft
17. We welcome the conclusion of the European
Commission feasibility study into the EU emissions trading scheme
that carbon trading is not a suitable policy instrument for addressing
the non-CO2 atmospheric effects of air transport.
18. Carbon offsetting is a close relative
of carbon trading and in many cases amounts to the same thing.
It is therefore logical that the use of a non-CO2 multiplier is
as equally unsuitable for carbon offsetting as it is for carbon
19. However, we recognise that scientific
uncertainty and inadequate metrics are not reasons for inaction
and British Airways supports a programme for addressing these
effects through commitments we have made in the UK Sustainable
(a) Provide relevant data and expertise for
the scientific community to enhance understanding of the non-CO2
atmospheric effects of air transport, and support improvements
in metrics for quantifying and reporting effects.
(b) Propose appropriate mechanisms by 2012
for mitigating non-CO2 effects based on a consensus of scientific
(c) Work with research councils, universities
and government departments to ensure that academic research is
linked with the air transport industry. Specifically, we support
establishing a network & regular workshops between scientific
researchers, industry and government.
(d) Continual improvement in technology towards
the ACARE target of an 80% reduction in NOx emissions by 2020,
based on new aircraft of 2020 relative to equivalent new aircraft
20. In addition, British Airways is a partner
an EU research project that aims to improve understanding of air
transport's NOx and cirrus effects by installing measuring equipment
on commercial in-service aircraft. Direct measurements of this
kind are essential to improving scientific knowledge of these
effects and to understanding the most appropriate instruments
for mitigating them.
21. NOx contributes to local air pollution
around airports and, during cruise, to the creation of tropospheric
ozone. Strenuous efforts have been made through technological
improvements to limit the contribution of aircraft NOx to the
local air quality burden around airports. Furthermore, EU air
quality standards are now placing considerable pressure on airlines
and engine manufacturers to reduce NOx emissions. The industry
expects to make further improvements with each new generation
of aircraft and engine design in line with the ACARE target for
new aircraft in 2020 to emit 80% less NOx relative to comparable
new aircraft in 2000.
22. These considerable improvements in NOx
emissions, driven by air quality stringency have a direct read-across
to reductions in NOx emissions at altitude. This relationship
was recently confirmed by the International Civil Aviation Organisation
Committee on Aviation Environmental Protection (ICAO CAEP) that
concluded "altitude NOx emissions performance for current
engines is controlled by LTO (Landing and take-off flight stage)
NOx emissions certification".
23. Aviation noise and emissions standards
have been successfully developed through ICAO for many years.
British Airways will continue to work proactively through ICAO
to secure tightening of NOx standards and to further develop long
term technology goals to reduce the impact of NOx emissions.
24. In our view, technological improvements,
specifically in response to demanding airport ambient air quality
standards in Europe, are currently sufficient to mitigate the
effects of NOx at altitude.
25. The UK Government should focus policy
initiatives for addressing aircraft non-CO2 effects on strengthening
atmospheric research. There is a need to raise the priority of
this work and ensure sufficient funding is directed to this objective.
30 April 2007
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