Climate Change and Tourism - UNEP - Division of Technology ...

194 Climate Change and Tourism – Responding to Global Challenges
Table A2.2 Assumptions for data by transport mode, trip number and distance based on expert
estimates
Assumptions
Indicator Value
Average car seat occupancy international tourism trips (persons/car) 2
Average car seat occupancy domestic tourism trips in high income countries (persons/car) 2
Average car seat occupancy in domestic tourism trips in developing countries (persons/car) 3
International non-air share of trips by car for same-day trips 80%
Share of same-day in high income countries of global domestic trips 70%
Average international return distance per non-air trip (km) 250
Average domestic return distance in high income countries per non-air trip (km) 250
Average return distance in developing countries per non-air trip (km) 200
A2.2.2 Tourism’s Share in Aviation
To calculate the tourism-related share of aviation, specific corrections needed to be made regarding
CO 2 emissions and RF as existing CO 2 emission inventories for aviation include all commercial aviation
(i.e., freight transport and passenger transport). 748, 749, 750 As only the share of tourism is to be included
in calculations, emissions caused by transport of freight needed to be subtracted from total emissions.
A conversion rate of 160 kg/pax was used to compare passenger and full freight versions of the same
aircraft. 751, 752 Interpolation of data for 1997 and 2010 shows that 19.5% of all aviation transport
volume (revenue ton kilometers) would have been freight 753 (see also Annex 1). Consequently, 80.5% of
all aviation emissions can be attributed to passenger trips. As the commercial aircraft fleet carries freight
and passengers more or less evenly, this share is assumed to reflect fuel consumption and emissions. It
should be taken into account that a small percentage of passenger traffic is not tourism, as passengers
might use the plane to commute or travel for a period longer than a year. Even though, the 80.5%
estimate is a conservative one, as international tourism itself entails some movement of freight by air to
cater for the consumption of tourists.
Passenger transport by air almost fully corresponds to overnight trips; same-day trips are estimated to
represent only some 1% of trips. As distance travelled on same-day trips can be expected substantially
lower than the overall average, the share in overall distance travelled and in emissions will be even
lower than 1%.
The emission factors for air transport are based on the figures and a method recently published by
Peeters et al. 754 This reference gives a distance correction factor (see Table A1) and furthermore a
wind correction factor (all emission factors are normally based on ISA (ICAO International Standard
Atmosphere) and no wind condition. Due to wind, more energy is lost at the head-wind sections than
gained at the tail-wind ones, a world average of 1.05 can be used. 755 The basic optimum emission
factor for 3500 can be set at 0.111 kg/pkm (ISA, no wind). 756 Using this value, we may fit for the
different average distances for the purpose of this report (see Table A2.3).
UNWTO, 9 July 2008