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

126 Climate Change and Tourism – Responding to Global Challenges
Figure 11.2 Tourist air transport: trips, passengers and CO 2 emissions, 2005
Share (%)
100
80
60
40
20
Radiative forcing by aviation
Emissions caused by aviation at flight altitude cause an additional warming effect. This effect may be
2–5 times the radiative forcing caused by CO 2 (see Box 23), and it is therefore important to make a
distinction between CO 2 emissions and the total contribution of aviation to radiative forcing (RF).
The radiative forcing caused by aviation is estimated to have contributed 0.053 W/m 2 (excluding the
impact of contrail-induced cirrus clouds) 642, 643 to the total human-induced radiative forcing of 1.6 W/
m 2 . 644 Aviation transport thus contributes 3.3% to global radiative forcing, not considering contrailinduced
cirrus clouds (note that the IPCC assumes a range of 2–8% as aviation’s contribution to global
RF; see also Box 23). The share of tourism travel in global aviation is estimated to be of 73% (for
calculations see Annex 2.2.2), and the corresponding RF for tourism related air transport would thus
be 0.039 W/m 2 or 2.5% (excluding cirrus) and up to 6.1% if the maximum estimate for cirrus-related
radiative forcing is considered.
11.1.2.2 Road and rail
The most important land-based tourism transport mode in industrialized countries is the car. 645, 646
Other transport modes, such as rail and coach, as well as water transport are less important in terms of
global passenger volumes, and even less so with respect to CO emissions, due to their relatively high
2
energy efficiency.
The CO 2 emissions from rail, coach and water-borne transport are more difficult to calculate because
data on the number and length of trips are more scattered and only available for a limited number of
countries. In this analysis, global emissions from international and domestic tourism are calculated for
each surface-based mode of transport by multiplying an estimated average distance travelled per trip by
the total number of trips and the emission factor per pkm (emission factors can be found in Table 11.2;
see Annex 2.2.1 for further details). To facilitate calculations, an average emission factor for coach and
rail (0.025 kg/pkm) was used. Further assumptions were made regarding average trip distances and the
modal split between car and other transport modes (including coach and rail; see Annex 2.2.1). The
results show that all tourism transport other than aviation, are estimated to have caused emissions of
465 Mt CO 2 , the bulk of this, 420 Mt CO 2, is estimated to be attributable to travel by car– Table 11.3).
Of all emissions by surface traffic, 122 Mt CO 2 corresponds to the 5 billion same-day trips (of which 4
billion are estimated to be domestic and 1 billion international, see Table 11.1). The 3.5 billion domestic
tourist trips (surface transport) account for 293 Mt CO 2 and the 410 million international tourist trips
(surface transport) to 49.5 Mt.
UNWTO, 9 July 2008
0
Trips (million) PKM (billion) CO 2 emissions (Mt)
Domestic
International
(intraregional)
International
(interregional)