Variation in offset price and
radiative forcing
123. Aviation is an area in which there is great
variance in the price of offsets which. While some variations
in price are not only to be expected but to be encouraged, since
there is a great variety of schemes from which offsets spring
and differing schemes inevitably have differing costs, a major
cause of the variation is differing calculations of carbon emissions
from flights of equal length. These variations cast doubt in the
eyes of many considering offsets on the rigour of the calculations
used to measure offsets and the validity of the array of figures
quoted.
124. The airlines cite, amongst other things, different
routes, different engines and different load factors to account
for the variations given for carbon released into the atmosphere
from journeys of similar or identical length by different airlines
and/or calculated by different offsetting companies or other online
carbon calculators. Recent research has highlighted the significant
number of relevant factors: flight distance, occupancy efficiency,
type of plane/engine, class of seat (since business seats are
more spaced out they have more carbon impact per seat than economy
seats), inclusion of a radiative forcing factor, and the simplicity
of the calculator used (ease of use as opposed to accuracy).
Research has also revealed that for identical journeys, calculations
of carbon released often differ considerably and the costs of
an offset to cover the carbon released differ even more. A paper
released in December 2006 from the Tufts Climate Initiative sets
out neatly how for a return flight from Boston to Washington DC
there were variances between calculations even in flight distance
of up to 10%. Calculations of emissions from the return flight
varied from 0.19 to 0.44 tons; and the cost of the appropriate
offset was cited from a low of $1.31 to a high of $18.40.[140]
Recent European research published in the Journal of Sustainable
Tourism has confirmed these variations: the amount of CO2
emissions calculated for a flight from Amsterdam to Barcelona
by various offset companies varies "by at least a factor
of 3 between companies". The costs of offsetting 1 tonne
of CO2-e vary by a factor of 15, and thus the cost
of an offset for the flight concerned can be as low as 1.92
or as high as 20.33.[141]
125. There is a need for an authoritative evaluation
so that the average consumer, whether individual or commercial
body, can assess the robustness of the various avenues for offsetting
available. We welcome the launch of DEFRA's Act on CO2
Calculator and hope that the data, methodologies and assumptions
upon which it is based prove acceptable to the airlines. We also
note that DEFRA is content for its work to be used by companies
in their own proprietary calculators, and we welcome the effect
this may have in helping standardize the currently too great range
of calculations for carbon emissions from flights. We also hope
that where airlines do not themselves offer a carbon calculator
they will be happy to refer customers to the Act on CO2
Calculator.
126. While it ought to be fairly straightforward
for DEFRA to provide some sensible average for CO2
emissions for a given length of flight, the issue of radiative
forcing has the capacity to make aviation offsets more complicated
and variable still. As we stated above, one of the reasons for
differing calculations for aviation offsetsin terms of
carbon effect and thus in terms of costwas down
to whether or not an RF factor was used: even if an RF factor
was used the size of the factor also varied considerably, from
just over 1 to almost 4. The original IPCC RF factor was set
at 2.7 but consensus until lately was concentrating on 1.9 following
research under the TRADEOFF project. The Treasury and the DfT,
amongst others, have themselves over time used different factors
in their own calculations, of 2.5 and 2, the later being used
in calculations for the GCOF.[142]
There is still no scientific consensus on the factor, its size
or temporal impact, and recent research indeed points towards
its likely inappropriateness for the calculation of climate effects
above and beyond those delivered by carbon. This research, which
has in effect been accepted by the Tyndall Centre for Climate
Change, but on which a broader critical consensus has yet clearly
to emerge, argues that non-CO2 multipliers based on
a radiative forcing index are a misapplication of science as they
fail to account for the resident timescale of emissions. British
Airways brought this research to our attention during oral evidence
and robustly stated its dissatisfaction with any automatic expectation
for offsets (or emissions trading) to take formal account of radiative
forcing: rather, appropriate calculations should be based purely
on CO2 emissions. The European Commission has itself
recently decided that the EU ETS is not an appropriate mechanism
for taking account of the effects of RF; and it may be the case
that over the next few months fewer and fewer offset companies
or schemes use an RF multiplier of any sort and thus some slight
parameters may appear around the range of offset cost for flights.
127. We believe there is clearly a need for new research
until some appropriate successor system to the current use of
the Radiative Forcing Index is identified and agreed upon. The
European Commission is engaged in drawing up an instrument that
will take account of aviation's non-CO2 effects, and
we support this approach whole-heartedly. Given the complexities
of climate change science, and the number of often conflicting
climatic factors for which aviation is responsible, it may well
be the case that no consensus emerges, or that there is insufficient
basis in science to conclude that aviation's impacts extend significantly
beyond its CO2 impacts. Nonetheless, the pure CO2
effects of aviation are sufficiently challenging to make the climatic
effects over and above that more grave still if they exist, and
actions to reduce carbon impacts will clearly likewise mitigate
other impacts should there be any. As the current use of RF factors
for offsets may be a source of confusion in the marketplace, and
as we agree that lack of agreement on a definite figure makes
the inclusion of such factors in the RF mortally problematic,
there is nevertheless a clear need for those who purchase flights
to understand that aviation's climate impact is not down to carbon
aloneand that even the most robust and accurate carbon
offset will not compensate fully for the climate effects of a
flight. We are pleased to see that DEFRA's assumptions for
aviation emissions on its Act on CO2 web-site, while making no
direct allowance for radiative forcing, do explicitly deal with
the issue, and that there are clear statements in its Frequently
Asked Questions section and in relevant Action Plans that the
effects of aviation on climate are greater than its carbon impacts
alone. It is also good to see that the web-site refers to the
Government's use of a radiative forcing factor in its own calculations.
We hope that such statements appear even more explicitly in whatever
calculator is agreed later in the year for use with the DEFRA
Code of Practice for offsetting.
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