Content uploaded by Stefan Gössling
Author content
All content in this area was uploaded by Stefan Gössling on Oct 12, 2017
Content may be subject to copyright.
1
Please quote as:
Gössling, S., Lohmann, M., Grimm, B. and Scott, D. 2017. Leisure travel distribution patterns of
Germans: Insights for climate policy. Case Studies In Transport
Policy, https://doi.org/10.1016/j.cstp.2017.10.001
German holiday transport patterns: Insights for climate policy
Abstract
Transport accounts for an estimated 23% of energy-related global CO2 emissions, a large share of
this for leisure and tourism purposes. Despite national and sector-specific pledges to reduce
global emissions of greenhouse gases, there are no consistent policies for the transport sector,
which is characterized by continued strong growth. Against this background, this paper
investigates holiday travel patterns of one of the most important tourism markets worldwide,
Germany, based on data from annual travel surveys (‘Reiseanalyse’, with n=7500). Data on trip
numbers, transport modes and travel distances are evaluated, indicating that emissions of
greenhouse gases related to holiday travel (including trips lasting 5 days and longer) are
significant at an average 320 kg CO2 per trip and person. Findings also show that the distribution
of holiday travel emissions is highly skewed among the population and heavily depending on trip
type. While about a quarter of the population does not participate in holiday travel at all, a small,
highly mobile and wealthier share of travellers, 4% of the German population, engages in five or
more holiday trips per year. These travellers are also more likely to participate in the most
carbon-intense trips, long-haul flights and cruises, which generate 2 t CO2 and more per trip.
Keywords: Aviation; Climate Change; Climate Policy; Cruise; Emissions; Germany; Tourism
1. Introduction
Emissions of anthropogenic greenhouse gases (GHG) totalled 49 ± 4.5 GtCO2eq/yr in 2010.
Transport is contributing 23% (6.7GtCO2) of total energy-related CO2 emissions (IPCC 2014a).
On global average, 72.1% of total direct emissions from transports are road-related, followed by
aviation (10.6%), and international and coastal shipping (9.3%) (IPCC 2014a). Aviation deserves
special attention, however, because a considerable share of this transport subsector’s emissions
are short-lived, and hence not comparable in terms of their global warming impact (Lee et al.
2009). In the future, emissions from transport are expected to grow, with the IPCC (2014a: 637)
noting that without policy interventions, transport related CO2 emissions could double by 2050,
and triple by 2100. Most of this will come from aviation, with Boeing (2015) and Airbus (2015)
anticipating growth in revenue passenger kilometres in the order of 4.9% per year. The
International Energy Agency suggests that this may lead to a tripling of energy use for aviation
by 2050 compared to 2005, and that the sector will by then account for 19% of all transport
energy (IEA 2009, high baseline scenario).
Emission growth in the transport sector is consequently in conflict with IPCC (2014a)
conclusions that drastic reductions in emissions will be necessary in the short-term future if
2
humanity is to stay within the ‘safe’ guardrail of a 2°C global average temperature increase,
compared to pre-industrial levels. To limit global warming to this level is the declared policy goal
of 196 countries that are parties to the United Nations Framework Convention on Climate
Change (UNFCCC 2012), and has recently been strengthened to ‘well below 2°C’ in the Paris
Agreement of the 21st Convention of Parties (COP21) in December 2015. This translates into a
global emissions budget from all anthropogenic sources of approximately 1,000 GtC, of which
some 65% have already been spent (IPCC 2014a). Countries have made a range of unconditional
and conditional pledges to limit GHG emissions (UNFCCC 2015), but analysis indicates that
current pledges will not be sufficient to meet the 2°C objective (Reilly et al. 2015). Given current
emission trajectories, it appears more likely that the CO2 emission budget for staying within the
2°C limit will be exhausted within 30 years (Friedlingstein et al. 2014). All economic sectors,
including tourism and transport, will thus have to make contributions to emission reductions.
Within this broader context, there is evidence that contributions to transport emissions are highly
skewed between countries and individuals (Brand and Boardman 2008; Brand and Preston 2010;
Gössling et al. 2009a,b; Lassen et al. 2006; Schäfer et al. 2009). To better understand these
interrelationships, and in particular the role of travel frequency (the number of trips per traveller
per year) and trip energy intensity (as a measure for emissions associated with a single holiday),
this paper analyses holiday travel patterns, which have received more limited attention in the
literature. Focus is on Germany, one of the most important tourism markets worldwide, based on
data from the national annual travel survey (“Reiseanalyse”). The purpose is to identify the most
emission-intense leisure trips, as well as traveller segments making more significant contributions
to climate change.
2. Climate policy and passenger transport emissions
The IPCC suggests that by 2050, reductions in transport CO2 emissions in the order of 15-40%
(against a 2010 baseline) could be achieved through a range of mitigation measures, including
“fuel carbon and energy intensity improvements, infrastructure development, behavioural change
and comprehensive policy implementation” (IPCC 2014b: 21). The design of “comprehensive”
transport policies to significantly reduce emissions remains however unclear with regard to the
focus of interventions (producer/consumer) as well as the type of policy (e.g. command-and-
control, market-based, voluntary).
Transport behaviour is primarily influenced by cost and time (Schäfer et al. 2009), and effective
transport policies could simply raise the cost of energy and/or GHG emissions, or remove fossil
fuel subsidies and other sector-specific state aid (OECD 2009, 2012, 2015). As an example, the
UK has maintained a long-standing duty on air travel, while national governments continue to
extend a range of significant subsidies to aviation (Gössling et al. 2017). As emissions from
shipping and car traffic remain equally unaddressed by legislation on both international and
national levels (UNFCCC 2015; OECD and UNEP 2011), there is broad academic consensus that
current policy measures are insufficient to achieve emission reductions necessary for the
transport and tourism sector to be consistent with international climate policy goals (e.g. Anable
et al., 2012; Banister, 2008, 2011; Chapman, 2007; Creutzig et al. 2015; Marsden and Rye 2010;
Peeters and Eijgelaar 2014).
Global policy approaches to reduce emissions are based on national per capita averages. This was
the basis for the Kyoto Protocol in 1997, as well as the Paris Agreement in 2015 with its focus on
3
‘common but differentiated’ mitigation goals (UNFCCC 2015). Table 1 shows distributions in
CO2 emissions in countries that are major contributors to global emissions. Transport emissions
account for between 6% (China) and 35% (France) of national CO2 emissions, and vary in
absolute terms between less than 0.1 t CO2 (India) and 4.5 t CO2 (USA) per person and year.
These relationships are of importance, as they illustrate that in countries such as the USA,
averaged annual emissions from transport are higher than those emitted on global average in
total.
Table 1: Emissions of CO2 by subsector, 2005*
Source: based on Schäfer et al. 2009; UNESA 2015
*Including emissions from international air traffic.
Differences in individual contributions to global emissions of greenhouse gases, irrespective of
country, are relevant for climate policy. With regard to international air travel, estimates of 3.5
billion passengers in 2015 (IATA 2015a) suggest that a large share of humanity is traveling by
air. However, as passengers are counted multiple times (arrival/departure, transfers) or engage in
multiple trips per year, it has been estimated that only 2-3% of the world population participate in
international air travel on an annual basis (Peeters et al. 2006). A distinction also needs to be
made between business and leisure travel, as business travellers are generally more mobile than
leisure travellers, perhaps with the exception of long-term backpackers (Cohen 2011). There are
both business and leisure travellers for whom frequent flying is a norm, sometimes involving
hundreds of individual flights per year (Gössling et al. 2009a,b; Hall 2005). Travel intensity
consequently varies: Ummel (2014) highlights this for the USA, where the top 2% income takers
have emission footprints four times larger than those in the bottom quintile. UNWTO (2015)
suggests that with regard to international travel, 14% of all trips are made for business and
professional reasons, 27% for visiting friends and relatives, health or religious reasons, and 53%
for leisure & recreation. In the future, the relative share of leisure, recreation and holiday related
travel is expected to increase (UNWTO 2011), indicating the significance of leisure-related travel
motives in a wealthier and growing world population.
Various studies have investigated business and leisure travel patterns. Lassen et al. (2006) found
that the average employee of Hewlett-Packard participated in 3.8 business international trips per
Country
CO2
emissions
(Mt)
Energy-
related
(Mt CO2)
Transportation
related (Mt
CO2)
Transport
as % of
total
Passenger
travel
(Mt CO2)
Passenger
travel per
capita
(t CO2)
Australia
United States
Russia
Germany
United Kingdom
Japan
France
China
India
World
393
6,140
1,780
894
596
1,320
434
5,300
1,270
28,200
384
6,090
1,740
873
558
1,290
417
5,170
1,250
27,900
91
1,920
165
184
171
281
154
335
110
6,370
23.2
31.3
9.3
20.6
28.7
21.3
35.5
6.3
8.7
22.6
60
1,340
86
132
106
170
85
135
47
3,890
2.9
4.5
0.6
1.6
1.8
1.3
1.4
0.1
<0.1
0.6
4
year, which virtually always involved air travel, covering 17,000 km on average. While 25% of
Hewlett-Packard employees did not participate in any trips at all, the most frequent traveller had
participated in 43 trips. A survey of travellers at Landvetter airport, Gothenburg, Sweden
(Gössling et al. 2009b) found that the 12% of the most mobile travellers had participated in at
least 30 and up to 300 return flights per year, 98% of these for business. The 3.8% of the most
frequent flyers (>50 return flights per year) accounted for 28% of all trips made. These studies
indicate highly skewed distributions of 'traveller to trip' and 'traveller to transport distance' ratios.
Studies investigating leisure travel patterns have also found considerable differences between
individuals. A study of international leisure tourists in Zanzibar, Tanzania (Gössling et al. 2006),
found, for instance, that the average per capita distance flown for leisure in 2002 and 2003 (air
travel only) was 34,000 passenger kilometres (pkm), excluding the trip to Zanzibar. The ten most
frequent travellers had flown almost 180,000 pkm each over the 22 months covered by the study,
visiting up to 24 countries. Together, these ten travellers (3.9% of the sample) accounted for 20%
of the overall distances travelled. Similar ratios have been found elsewhere. A study of the
French population revealed, for instance, that five per cent of the population accounted for 50%
of the distances travelled (Gössling et al. 2009a). The most frequent travellers in this study,
mostly individuals with net incomes exceeding 7,500 Euros per month, also chose more distant
destinations, covering distances 17.3 times greater than the average traveller. This leads to
skewed distributions in emissions, with for instance the top 10% of travellers causing 43% of
personal travel emissions (Brand and Boardman 2008).
Overall, these studies suggest that a small share of the most frequent travellers, including both
business and leisure travellers, is responsible for a disproportionately large share of transport
related emissions. More detailed, nationally representative studies of in particular holiday travel
patterns are however missing. Against this background, this paper investigates transport
distributions within the German-speaking population, i.e. interrelationships of travel frequencies
(trip numbers), distances travelled, and transport modes used. The overall purpose is to identify
the most emission-intense trips and traveller segments. Results are also compared to holiday
types, length of stay and spending, to derive further insights of relevance for climate policy.
3. Method
To understand the distribution of emissions from holiday travel, data contained in the German
‘Reiseanalyse’ (“travel analysis”) was evaluated with a focus on travel frequencies, distances
covered, and transport modes. Germany is the third largest nation in terms of tourism spending,
and an important outbound market (UNWTO 2015). ‘Reiseanalyse’ (RA) is a representative
survey of the holiday travel behaviour of the German-speaking population that has been carried
out since 1970. The survey is focused on holiday travel with a trip length of five days or more.
Data collection relies on random route samples involving face-to-face interviews (Bauer 2016).
Face-to-face data compiled in the RA 2015 is the basis for this article, including n=7,720
personal interviews in the home of the respondents. This is representative of the German-
speaking population aged 14 and above living in private households, comprising 70.5 million
individuals (Schmücker et al. 2015). Note that with regard to definitions, focus is on holiday
trips, which involve two legs (going/returning), and both domestic as well as international
holiday trips lasting at least 5 days.
5
The analysis has the purpose to shed light on the contribution made by frequent holiday travellers
as well as specifically energy-intense holiday trips to emissions of greenhouse gases. Data is
analysed with regard to travel frequencies, distances travelled, and transport modes. Travel
frequencies are analysed on the basis of trip numbers. Existing studies have used classifications
of ‘non-mobile’ (no international trips), ‘slightly mobile’ (1 international trip per year), ‘fairly
mobile’ (2 trips), ‘highly mobile’ (3-5 trips) and ‘hypermobile’ (6 or more trips per year)
travellers (Frändberg and Vilhelmson 2003); as well as cluster-based classifications including
‘immobiles’, ‘frequent travellers on short trips’ (<3 days), ‘travellers using trains or cars with a
focus on destinations within home country’, ‘travellers on aircraft, favouring European
destinations’, and ‘frequent travellers in home country and abroad, using all transport modes’
(Gössling et al. 2009a). In this study, the Frändberg and Vilhelmson (2003) classification is used,
though three or more trips define the most frequent travellers. Analysis distinguishes
‘nonmobiles’ (no holiday trips), ‘slightly mobiles’ (one holiday trip per year), ‘fairly mobiles’
(two holiday trips per year) and ‘highly mobiles’ (three or more holiday trips).
Furthermore, given the importance of specific trips in generating emissions (Eijgelaar et al.
2010), highly energy and emission-intense holidays were also identified. Such ‘carbon holidays’
were defined to involve travel distances exceeding 2,000 km (one way) and the use of aircraft as
transport mode. Given the carbon-intensity of cruises, all cruise trips are also considered ‘carbon
holidays’. Trip distances for all journeys were calculated for city-to-city great circle (air) or
terrestrial (road) distances. Note that city-to-city great circle calculations will underestimate true
travel distances, as air travel often involves detours, for instance in the case of no-fly zones. Per
traveller/trip emission calculations are based on (passenger kilometre) distances travelled with
different transport modes and multiplied by emission factors specific for these transport modes
and the German transport system. More specifically, this includes data for German railways at
0.011 kg CO2/pkm for electric highspeed trains (note that the 2014 average throughout the
German railway system is 0.056 kg CO2/pkm; Bahn 2015). For German cars, the average is 0.044
g CO2/pkm in 2015, based on IFEU (2012). Distance-based air transport emission factors are
derived from Gössling et al. (2015) (0.099-0.183 kg CO2/pkm in 2015), while cruise emissions
are calculated on the basis of estimates for per day emissions (at a global average of 169 kg
CO2/day; Eijgelaar et al. 2010). All calculations focus on CO2, and do only consider energy
throughput. This focus consequently omits the considerable additional warming effect of
emissions from aviation released at flight altitude (Lee et al. 2009), as well as potentially
significant lifecycle emissions (transport mode production) as well as emissions related to
infrastructure construction and maintenance (e.g. Chester and Horvath 2009; von Rozycki et al.
2003).
Two limitations of the RA survey need to be highlighted. First, a share of very highly mobile
travellers is likely to be excluded in the data, as very wealthy travellers that use personal forms of
transport (private or corporate aircraft or yachts) are not captured in random route sampling
procedures and thus not adequately represented in the data. Second, for the highly mobile,
business and leisure trip motives may often merge (Gössling et al. 2009a). As a result of these
omissions, data presented in the following sections needs to be considered a conservative
assessment.
4. Results
6
Table 2 shows the distribution of holiday travel intensities in the German-speaking population,
expressed in the number of trips made by individuals in 2014. About a quarter of the population,
the ‘non-mobiles’, did not participate in holiday travel at all. The largest group, ‘slightly mobiles’
(61%), participated in one holiday trip. ‘Fairly mobile’ travellers engaged in two holiday trips
(13%). Finally, the ‘highly mobiles’ (4%, or 2.8 million people) engaged in 9.52 million trips,
corresponding to 14% of all holiday trips (average: 3.4 trips per traveller). Across the share of the
German-speaking population that participated in holiday travel, the average travel frequency is
1.3 trips per year.
Table 2: Distribution of holiday trips with a length of at least 5 days, 2014
%
population
million
travellers
%
trips
million
trips
Non-mobiles
23
15.94
0
0
Slightly
mobiles
61
42.89
61
42.89
Fairly
mobiles
13
8.89
25
17.78
Highly
mobiles
4
2.80
14
9.52
Total
100
70.52
100
70.3
Database: German-speaking population aged 14 and older
Definitions: non-mobiles: no holiday trips; slightly mobiles: one holiday trip per year; fairly
mobiles: two holiday trips per year; highly mobiles: three or more holiday trips per year.
Source: FUR 2015 (RA 2015 face-to-face)
Further analysis with regard to trip distances indicates the relevance of this parameter for
emissions, as long distances virtually always involve energy-intense air travel. Table 3 shows that
trips over distances between 500-999 km account for one quarter (24%) of all trips, and trips
between 1000-1999 km for another quarter (26%). Trips between 2000-9999 km and those
>10,000 km accounted for 19% and 2% of trip numbers, respectively. In absolute numbers, the
1.44 million trips >10,000 pkm generated a travel volume of 17.13 billion pkm (14.7%).
Together with the 2000-9999 km distance class, the 21% of the most distant trips (14.89 million)
thus accounted for 59.7% (69.35 billion pkm) of all distances travelled. These most energy-
intense ‘carbon holidays’ mostly involve air travel (98%), while cruises account for 2%. Overall,
German’s total holiday travel was 232 billion pkm in 2014 (including return trips), 74% of this by
air (172 billion pkm), 18% by car (42 billion pkm by car), 4% by bus (8 billion pkm) and 2%
(4 billion pkm) by train. In addition, considerable distances are travelled by cruise ship, though
there is no data on this.
Table 3: Holiday-trips (>5 days) by one-way distance, 2014
%
million
trips
total distance
(one way, billion
km)
<500 km
29
20.42
6.46
7
500-999 km
24
17.06
11.89
1,000-1,999 km
26
17.91
25.20
2,000-9,999 km
19
13.45
55.58
10,000 km >
2
1.44
17.13
Total
100%
70.3
116.26
Database: German-speaking population aged 14 and older
Source: FUR (RA 2015 face-to-face)
A more refined understanding of the climate impact of holiday travel emerges if emission
distribution ratios from these trips are calculated for transport modes. Table 4 shows this
distribution by transport mode and per trip, indicating that total transport emissions from German
holiday travel amounted to 22.7 Mt CO2 in 2014. This estimate includes train (0.2% of total
emissions); bus (1.1%); car (8.1%); air travel (77.4%); cruise (11%); travel to cruise port of
departure/arrival (1.7%); ship (mostly ferries; 0.5%); and other transport (motorcycle; <0.1%). As
outlined, this estimate only considers energy throughput with a focus on CO2. The data also
reveals that long-haul flights (>10,000 km one way) have a disproportionally large climate
impact: Even though representing less than 2% of all trips, they account for 14% of CO2. Cruise
trips are equally energy intense, at 1.4% of holidays they contribute 12.7% of emissions
(including travel to/from port). In comparison, train and bus are insignificant in terms of
emissions (0.2% and 1.1%, respectively), yet representing 13% of trips. Cars cause 8.1% of
emissions, even though they are the most often used transport mode (45% of all trips). Note that
the estimate does not consider travel in the destination and higher energy requirements of camper
vans and mobile homes. Findings underline the importance of long-haul flights and cruises in
adding to national holiday emissions. This is also illustrated in Figure 1, which shows the
contribution of different transport modes to overall emissions, in relation to trip numbers. Air
transport is divided into distance classes.
Table 4: CO2-emissions by main transport mode, 2014
million
trips
Return
distance
(km)
Emission
factor
(kg CO2/pkm)
Emissions
per trip
(kg)***
CO2 emissions
(Mt)
%
Train
3.61
1,072
0,011
12
0.043
0.2
Bus
5.44
1,528
0,030
46
0.249
1.1
Car
32.11
1,298
0,044
57
1.834
8.1
Air <500 km
0.2
690
0,183
126
0.025
0.1
500-999
1.46
1,558
0,137
218
0.311
1.4
1,000-1,499
6.61
2,582
0,116
300
1.979
8.7
1,500-1,999
5.04
3,429
0,108
370
1.858
8.2
2,000-9,999
12.47
8,289
0.099
821
10.238
45.0
10,000 km>
1.35
23,817
0.099
2,358
3.183
14.0
Cruise
Travel to cruise
0.97
-
169 kg/day
mixed calc.
1,910
mixed calc.
2.502
0.389
11.0
1.7
Ship*
0.34
1,000
0.350
350
0.119
0.5
Other**
0.65
804
0.005
4
0.003
0.0
Total
70.3
-
-
323
22.733
100,0
8
German-speaking population aged 14 and older, holiday trips 5+ days; * without cruises, distance
unknown, estimate; ** e.g. bicycle and motorcycle, estimate for average emissions; *** transport
to/from destination only. Omits travel within destination. The opposite is true for cruise, which is
based on 11.3 cruise days; travel to port of departure/arrival is calculated separately and included
in ‘travel to cruise’.
Source: Bahn 2015; FUR 2015 (RA 2015 face-to-face); Eijgelaar et al. 2010; IFEU 2012
Figure 2: Holiday transport modes as percentage of trips and emissions
Source: Authors
Comparative emissions per trip are illustrated in Figure 2. Train-based holidays involve the
smallest carbon footprints, at 12 kg CO2, followed by bus (46 kg CO2) and car (57 kg CO2). Car-
based holidays are comparably climate-friendly as a result of load factors, at 3.2 persons per car.
All air travel is carbon-intense, though the figure illustrates that in particular trips with one-way
distances exceeding 2,000 km and cruises contribute disproportionally to overall emissions. Air
travel exceeding one-way distances of 10,000 km results in about 2.4 t CO2, and cruise trips 2 t
CO2. Any such transport mode thus ‘depletes’ a sustainable annual per capita carbon budget, at
an estimated 4 t CO2 per capita and year, by more than half. This estimate is based on the
assumption that current globally averaged emissions of approximately 4.5 t CO2 per person and
year are not climatically sustainable (IPCC 2014a).
9
Note: cruise trips are not directly comparable with other trips, because this type of holiday is based on
constant movement, while transport has the purpose of overcoming distance to arrive in a given
destination for all other trips. Thus, we don’t provide an average distance for cruise trips.
Figure 2: Average emissions and one-way distances per holiday trip and main transport
mode
Source: Authors
Emissions can also be broken down to individual ‘per traveller’ contributions. An analysis of the
100 most mobile travellers of the sample (in trip numbers) suggests that these participated in five
to 12 holiday trips (>5 days) in 2014. Distances covered varied between 2,704 km and 58,112 km
(all holiday trips in 2014; return distance). Analysis of these trips suggests that travel frequency is
not necessarily a predictor of emissions. For example, one traveller participating in 12 trips
emitted less than 15 kg CO2 in total, because all trips were by train and involved close
destinations. In comparison, the five holiday trips of another traveller, four of these cruises,
contributed to more than 8 t CO2. A relationship was however found between the number of
holiday trips taken by individual travellers and the share of ‘carbon holidays’ with a return
distance exceeding 4,000 km. In other words, more mobile travellers are more likely to engage in
longer trips. Among the slightly mobiles, one fifth (21%) engaged in ‘carbon holidays’; a share
that increased to 27% among the fairly mobiles, and to 74% among the highly mobiles (Table 5).
Table 5: Participation in ‘carbon holidays’ by traveller classification
10
Slightly mobiles
Fairly mobiles
Highly mobiles
All holiday trips
(million)
Carbon holidays as
number/share of all
holiday trips:
42.89
8.89
1.1
million
9.17
2.41
0.8
as share of trips
21%
27%
74%
Definition ‘carbon holidays’: holiday trips with a length of five or more days, covering a one-way-distance of more
than 2,000 km and involving the use of aircraft or ship as the main transport mode.
Definition of segments: ‘slightly mobiles’: one holiday trip per year; ‘fairly mobiles’: 2 holiday trips per year;
‘highly mobiles’: three or more holiday trips.
Source: FUR 2015 (RA 2015 face-to-face)
Data on holiday transport distributions was also analysed in the context of sociodemographic
traveller characteristics. Among the highly mobiles, 61% are female and 39% male, and a large
share of them is older (average: 53 years; with 30% being 70 years and above). Highly mobile
travellers are characterized by a higher formal education, and claim above average household
incomes. Holiday motives differ, with highly mobiles valuing aspects of “get to know other
countries, see the world” (+43 percentage points, compared to general traveller population), “do
something cultural and educational” (+36), “get completely new impressions, discover something
totally different” (+33), “new experiences, diversion from the ordinary” (+28), “travel around, be
on the move” (+18), and “meet the locals” (+18). Holiday activities are also significantly
different from other travellers, including “visiting natural attractions” (+37, compared to general
population), “visiting sites of cultural or historical interest/ museums” (+34), and “trips,
excursions” (+26). In contrast, only a third of the highly mobiles (35%) have an interest in
environmentally friendly holidays, compared to 42% in the general population.
With regard to the share of the most carbon-intense trips, analysis reveals that these are mostly
made in summer (37%; average distribution 49%), as well as in autumn (28%; 23%). ‘Carbon
holidays’ last longer than other holiday trips, on average 15.8 days, compared to 12.5 days for the
average German holiday trip. Three quarters (75%) of carbon holidays involve hotels for
accommodation, compared to 46% for the average holiday trip. Spending for ‘carbon holidays’ is
67% higher, at €1,603 per trip and person, compared to €958 for the average traveller. Per person
per day, spending for ‘carbon holidays’ is 34% higher, at €109 per person per day, compared to
€81 per person per day for the average holiday. ‘Carbon holidays’ are particularly often sun-sand-
sea holidays (34%, as compared to 21% on average). These insights create additional
complexities for climate policy, and are discussed in the following.
5. Discussion
The main purpose of this paper was to analyse leisure travel patterns of the German population,
and to derive insights for climate policy. A number of key insights emerge from the results. First
of all, among the 7,500 respondents, the greatest number of holiday trips was 12, and the
maximum distance travelled 58,112 pkm. This is lower than the distances travelled by tourists in
11
long-haul destinations such as Zanzibar (Gössling et al. 2006), where more mobile traveller
populations may concentrate. In particular backpackers can be constantly on the move, described
by Cohen (2011) as ‘lifestyle travellers’. It is possible that these are underrepresented in this
sample. Socio-demographics of the most highly mobile travellers in this study however reveal
that these travellers often belong to the high to very high income segments of the population, with
travel motives such as ‘being on the move’ or ‘sun, sand, and sea’.
Findings reveal that holiday travel of the German-speaking population causes emissions in the
order of 22.7 Mt CO2, i.e. corresponding to the equivalent of about 16% of German CO2
emissions from transport (about 163 Mt CO2; UBA 2016). This estimate does only include
holiday trips of 5 days and more, and excludes accommodation or travel in the destination. It is
based on the assessment of energy throughput, and ignores considerable lifecycle emissions.
Averaged, a German holiday trip (transport) entails 320 kg CO2, and the average German’s
contribution to leisure holiday travel is 415 kg CO2 per year (at 1.3 trips, for the 77% of the
population taking holidays).
Further insights were derived from the analysis of ratios, with 4% of travellers engaging in 14%
of trips, and the 15% most distant trips accounting for 60% of the total distances travelled. These
long-haul trips also generate a large share of overall emissions. The top quartile of the most
energy-consuming trips results in 70% of all holiday CO2. Considering even non-CO2 emissions,
the contribution of these trips to global warming is even higher. On a per trip basis, long-haul
flights (>10.000 km) and cruise ship holidays are thus more relevant for climate policy than other
holidays. In Germany, average holiday distances grew from 1,415 km to 1,600 km between 2002
and 2011 (+13%; Frick & Grimm 2014, Grimm & Schmücker 2015), a trend mostly explained by
growth in air travel (Lohmann et al. 2014). These insights confirm the need to regulate long-haul
air travel and cruises in highly developed tourism economies.
Currently, emissions from aviation and shipping are not covered by national policies. Aviation
emission reductions are to be pursued through the International Civil Aviation Organisation
(ICAO), in recognition of the difficulty of assigning responsibility for international emissions to
individual countries (Clarke and Chagas 2009). Emissions from ships are the mandate of the
International Maritime Organization (IMO) (Bows-Larkin et al. 2015). The European
Parliament’s Committee on Environment, Public Health and Food Safety (2015: 9) concludes that
“Initiatives and actions taken by ICAO and IMO to address GHG emissions started late and have
been insufficient from an environmental perspective to date: they do not take appropriate account
of global decarbonisation requirements”.
Currently two major international efforts aim to stabilize and eventually reduce emissions from
air travel, including the European Union’s Emission Trading Scheme (EU ETS) and ICAO’s
Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) scheme. The EU
Commission independently developed proposals for including aviation in its Emission Trading
Scheme that imposes caps on large emitters. Aviation has been included since 2012. The scheme
currently only applies to flights within the territory of the European Economic Area countries
(i.e. the EU28, Iceland, Liechtenstein and Norway). In 2013, under pressure to allow airlines time
to find international consensus at the ICAO level, international aviation was frozen from the ETS.
The amended EU ETS Directive specifies that once the ICAO mitigation proposal (CORSIA) is
available, the Commission should report to the European Parliament and to the Council on the
12
matter and if appropriate prepare a proposal amending the directive (Europa 2017). Even though
it is unclear how the EU Parliament and Council will decide on the issue, CORSIA has already
been challenged as an insufficient approach to mitigation, because the scheme:
• Only covers CO2, ignoring non-CO2 emissions that are estimated to have the same order
of magnitude as the forcing caused by CO2.
• Applies to only to 80% international air traffic, due to various exceptions, such as Small
Island Developing States (EC 2017).
• Only covers emissions exceeding 2020 levels (i.e. it allows the sector to grow for another
three years in emissions, before additional emissions will be ‘covered’ by the scheme).
• Is voluntary in its pilot (2021 through 2023) and first phase (2024-2026), involving only a
share of airlines for at least another decade. Only after 2035 would most airlines be forced
to join.
• Even though only a small share of emissions from aviation will be covered, the scheme
would require offsetting at unprecedented scales. This will result in a situation where the
scale of projects increases every year while available project opportunities decline. If
expected breakthroughs in alternate low-carbon fuels do not materialize as early as
projected, the requirements for offsetting credits would escalate rapidly after 2030.
• Plans to source offset credits through low-cost projects, including Reduced Emissions
from Deforestation and Forest Degradation in Developing Countries (REDD+). Forest
projects have been criticized as highly unreliable offset projects, which in the case of
REDD+ do not sequester carbon, rather than continue to maintain existing carbon pools.
This will lead to a situation where atmospheric concentrations of CO2 rise, even where
projects work.
In the absence of credible international strategies to reduce emissions from aviation and shipping,
national climate policy regains importance (OECD and UNEP 2011). The Organization of
Economic Cooperation and Development (OECD 2003, 2005, 2012) repeatedly outlined that
removing subsidies and imposing a cost on fossil fuels is the most efficient approach to reduce
emissions, consistent with the polluter pays principle. Given that the contribution made by air
travel to overall emissions increases with distance, there is a need to specifically address long-
haul flights in climate policies. Low cost air travel is also of relevance, as the sector delivers
cheap mobility to mass markets, creating interest in aviation and turning air travel into a norm.
Research as presented in this paper also raises the question of travel motives. There has been a
longstanding argument that a considerable share of air travel is ‘induced’ by low fares (Nilsson
2009), while more recent research also raises the prospect of travel for social capital generation
(Gössling and Stavrinidi 2016). This is reflected in findings, where travel motivations include
“being on the move”. In a carbon-constrained future, there may have to be a debate as to what
travel is desirable. This is also true for cruises, which are specifically problematic from a climate
change point of view.
Complexities arise out of insights that a share of travel affected by national climate policies
would involve trips desirable from destination viewpoints: this includes trips made during low-
season, with greater trip-length, by travellers who are potentially flexible in their spending, or
who spend more than “average” travellers. Many of the trips contributing most to emissions are
13
made in spring and autumn, which is of relevance given many destinations’ struggle to attract
low-season visitors, and hence these destinations’ economic viability. Climate policy may have to
consider this, also because demand in high season influences the overall capacity considered
economically viable by airlines and cruise operators (measured in airport or cruise port capacity,
or seat numbers/berths). To reduce high season capacity is likely to also have repercussions for
load factors: Currently, one in five air seats are flown empty (IATA 2015b). Evening out demand
would also affect air travel demand growth and price structures, but may require greater
flexibility in European holiday periods. The implementation of national climate policies in the
transport sector would also force destinations to reconsider their products and marketing
strategies, and to invest greater efforts into the optimization of their systems.
Finally, results confirm considerable differences in travel activity. Climate policy will
consequently have to consider principles of equity that underline the Paris Agreement. The
transport sector provides ample evidence that it is a very small share of wealthy citizens
contributing disproportionally to emissions (Brand and Boardman 2008; Brand and Preston 2010;
Ummel 2014). Even though a phenomenon more generally associated with the USA, where the
wealthiest have their own travel networks (Frank 2007), evidence grows that without tackling the
travel patterns of the most mobile, mitigation in line with IPCC recommendations is unfeasible.
6. Conclusions
This paper evaluated German leisure travel data for holidays lasting five days or longer, with the
overall goal to derive insights for the design of climate policies. Results show that there are
significant differences in holiday participation and the emissions caused by individual trips or
travellers. On one side of the spectrum, 23% of the population do not participate in leisure travel
at all, while a small share of the population (4%) engages in three or more holiday trips per year.
These travellers were also more likely to participate in the most carbon-intense trips, defined as
air travel with return-distances exceeding 4,000 km, as well as cruises. Long-haul flights with
return distances exceeding 20,000 km were found to generate almost 2.4 t CO2 per trip, while
cruises, at an average length of 11.3 days, produced emissions of 2.0 t CO2 per trip. As a result,
the 3% of the most energy-intense trips contribute to 25% of all holiday transport emissions in
Germany. Flights between 2,000-10,000 km (12% of all trips) contribute another 45%. Taken
together, 15% of the trips thus generate 70% of German’s holiday transport emissions.
For climate policies to be efficient, it is crucial to focus on these travel segments. In the absence
of credible international sectoral strategies to reduce emissions, aviation and cruises may have to
be targeted at the national scale. An example of a feasible strategy is the UK’s air passenger duty,
which includes distance ‘bands’ and flight class considerations, and is thus somewhat
proportional to emissions. A variety of countries in Europe have introduced or plan to introduce
similar duties, though these could more accurately reflect the climate implications of different
trips, as well as the fact that highly mobile travellers are disproportionally more wealthy.
Precedents for the application of non-linear carbon costs to other consumer transport decision
contexts exist, for example in the form of bonus/malus systems (D’Haultfœuille et al. 2011).
International tourism is a form of economic activity that is no more essential to economic
development than electricity generation; steel, cement, or chemical production. All of these other
economic sectors will have more stringent emission reduction expectations and requirements
placed upon them through country pledges to the Paris Agreement and the tourism sector cannot
14
expect special status exemptions if the goal of the international community to restrict global
warming to ‘well below 2°C’ is to be achieved. The overall cost of action for tourism in line with
international climate objectives has been shown to be comparably low (Scott et al. 2015), and as
insights from this paper suggest, tailored climate policy increasing the cost of in particular carbon
intense holidays will represents an important step in meeting the sector’s decarbonization
challenge.
References
Airbus (2015). Global Market Forecast 2015-2034. Available at:
http://www.airbus.com/company/market/forecast/ Accessed 1 October 2015.
Anable, J., Brand, C., Tran, M., & Eyre, N. (2012). Modeling transport energy demand: A socio-
technical approach. Energy Policy, 41, 125–138.
Bahn (2015). CO2-Emissionen reduziert [CO2 emissions reduced]. Available:
http://ib2014.deutschebahn.com/ib2014-de/konzern-lagebericht/konzernperformance-
oekologie/klimaschutz/co2-emissionen-reduziert.html Accessed 15 December 2015.
Banister, D. (2008). The sustainable mobility paradigm. Transportation Policy, 15(1), 73–80.
Banister, D. (2011). Cities, mobility and climate change. Journal of Transport Geography, 19(6),
1538–1546.
Bauer, J.J. (2016). Biases in Random Route Surveys. Journal of Survey Statistics and
Methodology, Volume 4, Issue 2, 1 June 2016, Pages 263-
287, https://doi.org/10.1093/jssam/smw012
Boeing (2015). Current Market Outlook 2015-2034. Available at:
http://www.boeing.com/resources/boeingdotcom/commercial/about-our-
market/assets/downloads/Boeing_Current_Market_Outlook_2015.pdf Accessed 1 October 2015.
Bows-Larkin, A., Anderson, K., Mander, S., Traut, M., & Walsh, C. (2015). Shipping charts a
high carbon course. Nature Climate Change, 5(4), 293-295.
Brand, C. and Boardman, B. (2008) Taming of the few – The unequal distribution of greenhouse
gas emissions from personal travel in the UK. Energy Policy, 36(1): 224-238.
Brand, C. and Preston, J.M. (2010) '60-20 emission' - The unequal distribution of greenhouse gas
emissions from personal, non-business travel in the UK. Transport Policy, 17(1): 9-19.
Brand, C., Goodman, A., Rutter, H., Song, Y. and Ogilvie, D. (2013). Associations of individual,
household and environmental characteristics with carbon dioxide emissions from motorised
passenger travel. Applied Energy, 104, 158-169.
Chapman, L. (2007). Transport and climate change: a review. Journal of Transport Geography,
15(5), 354-367.
Chester, M. V., & Horvath, A. (2009). Environmental assessment of passenger transportation
should include infrastructure and supply chains. Environmental Research Letters, 4(2), 024008.
Clarke, C.F.C. & Chagas, T. (2009). Aviation and Climate Change Regulation. In: Freestone, D.
& Streck, C. (eds) 2009. Legal aspects of carbon trading: Kyoto, Copenhagen, and beyond.
Oxford, New York: Oxford University Press, pp. 606-623.
Cohen, S. A. (2011). Lifestyle Travellers. Annals of Tourism Research 38 (4): 1535–1555.
15
Creutzig, F., Jochem, P., Edelenbosch, O.Y., Mattauch, L., van Vuuren, D.P., McCollum, D. and
Minx, J. (2015). Transport: A road block to climate change mitigation? Science, 350(6263), 911-
912.
D’Haultfœuille, X., Durrmeyer, I. and Février, P. 2011. Le coût du bonus/malus écologique: Que
pouvait-on prédire? Revue Économique 62(3), 491–499.
Department of Transport (2003). Aviation White Paper. Annex A - UK air travel forecasts.
Available at: http://www.dft.gov.uk/about/strategy/whitepapers/air/ Accessed 21 January 2008.
EC (European Commission) (2015). Reducing emissions from transport. Available
http://ec.europa.eu/clima/policies/transport/index_en.htm Accessed 2 November 2015.
Eijgelaar, E., Thaper, C., & Peeters, P. (2010). Antarctic cruise tourism: the paradoxes of
ambassadorship,“last chance tourism” and greenhouse gas emissions. Journal of Sustainable
Tourism, 18(3), 337-354.
Eijgelaar, E. , Peeters, P., de Bruijn, K., & Dirven, R. (2015) Travelling large in 2014:
The carbon footprint of Dutch holidaymakers in 2014 and the development since 2002. Breda,
The Netherlands: NHTV Breda University of Applied Sciences.
Europa (2017). Aviation in the EU Emission Trading System – Implementing the ICAO October
2016 Agreement. Available: http://www.europarl.europa.eu/legislative-train/theme-resilient-
energy-union-with-a-climate-change-policy/file-eu-ets-aviation-implementation-of-the-2016-
icao-agreement Accessed 11 September 2017.
European Commission (2014). Reducing emissions from aviation. Available at:
http://ec.europa.eu/clima/policies/transport/aviation/index_en.htm Accessed 19 November 2014.
Featherstone, M. (2014). Super-rich lifestyles. In Birtchnell, T. & Caletrío, J. (eds). Elite
Mobilities. London, Routledge: 99-135.
Frändberg, L. and Vilhelmson, B. (2003). Personal mobility: a corporeal dimension of
transnationalisation. The case of long-distance travel from Sweden. Environment and Planning A,
35(10), 1751-1768.
Frank, R. (2007). Richi$tan. A Journey through the 21st Century Wealth Boom and the Lives of
the New Rich. New York: PIatkus.
Frick, R. and Grimm, B. (2014). Long distance mobility – Current trends and future perspectives.
Munich: Institute for Mobility Research.
Friedlingstein, P., Andrew, R. M., Rogelj, J., Peters, G. P., Canadell, J. G., Knutti, R., Luderer,
G., Raupach, M.R., Schaeffer, M., van Vuuren, D.P. & Le Quéré, C. (2014). Persistent growth of
CO2 emissions and implications for reaching climate targets. Nature Geoscience, 7(10), 709-715.
FUR - Forschungsgemeinschaft Urlaub und Reisen (2015). Reiseanalyse - Representative survey
of the holiday travel behaviour of German-speaking population in Germany, their related
attitudes, motivations and interests. Kiel: FUR.
Gillen, D.W., Morrison, W.G., Stewart, C., (2003). Air Travel Demand Elasticities: Concepts,
Issues and Measurement. Department of Finance, Government of Canada. Available at:
http://www.fin.gc.ca/consultresp/Airtravel/airtravStdy_e.html Accessed 21 January 2008.
16
Goodman, A., Brand, C. and Ogilvie, D. (2012) Associations of health, physical activity and
weight status with motorised travel and transport carbon dioxide emissions: a cross-sectional,
observational study. Environmental Health, 11(52).
Gössling, S., Bredberg, M., Randow, A., Svensson, P. and Swedlin, E. (2006). Tourist
perceptions of climate change: a study of international tourists in Zanzibar. Current Issues in
Tourism 9(4-5): 419-435.
Gössling, S., Ceron, J.-P., Dubois, G., and Hall, C.M. (2009a). Hypermobile travellers. In
Gössling, S. and Upham, P. (Eds). Climate Change and Aviation. Earthscan, pp. 131-149.
Gössling, S., Hultman, J., Haglund, L, Källgren, H. and Revahl, M. (2009b). Voluntary carbon
offsetting by Swedish Air Travellers: Towards the Co-creation of Environmental Value? Current
Issues in Tourism, 12(1): 1-19. DOI:10.1080/13683500802220687
Gössling, S., Scott, D., & Hall, C. M. (2015). Inter-market variability in CO2 emission-intensities
in tourism: Implications for destination marketing and carbon management. Tourism
Management, 46, 203-212.
Gössling, S., Fichert, F. and Forsyth, P. 2017. Subsidies in
aviation. Sustainability, http://www.mdpi.com/2071-1050/9/8/1295
Grimm, B. and Schmücker, D. (2015). Entwicklungen und Perspektiven im Bereich der
Urlaubsmobilität – Verkehrsmittelwahl und Reisedistanzen der deutschen Urlauber. In: Egger, R.
& Luger, K. (Eds): Tourismus und mobile Freizeit. Lebensformen, Trends, Herausforderungen,
pp. 93-108. Salzburg.
Hall, C.M. (2005). Tourism. Rethinking the Social Science of Mobility. Harlow: Pearson.
Higham, J.E.S., Cohen, S.A., and Cavaliere, C.T. (2014). Climate change, discretionary air travel
and the ‘flyers’ dilemma’. Journal of Travel Research, 53(4): 462-475.
IATA (2015a). Total passengers set to double to 7 billion by 2034. Available from:
https://www.iata.org/pressroom/pr/Pages/2015-11-26-01.aspx Accessed: 08.03.2016.
IATA (2015b). Airline Profitability Strengthens Further. Available at:
http://www.iata.org/pressroom/pr/Pages/2015-06-08-03.aspx Accessed 02.04.2016.
IEA (International Energy Agency). (2009). Transport, Energy and CO2: Moving Towards
Sustainability. Paris: International Energy Agency.
IFEU (2012). Aktualisierung ”Daten- und Rechenmodell: Energieverbrauch und
Schadstoffemissionen des motorisierten Verkehrs in Deutschland 1960-2030“ (TREMOD,
Version 5.3) fr die Emissionsberichtserstattung 2013 (Berichtsperiode 1990-2011). Available at:
http://www.ifeu.de/verkehrundumwelt/pdf/IFEU(2012)_Bericht%20TREMOD%20FKZ%20360
%2016%20037_121113.pdf Accessed 10 February 2016.
IPCC (2014a). Climate Change 2014: Mitigation of Climate Change. Contribution of Working
Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change
[Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I.
Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T.
Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and
New York, NY, USA.
17
IPCC, (2014b): Summary for Policymakers. In: Climate Change 2014: Mitigation of Climate
Change. Contribution of Working Group III to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E.
Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J.
Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge
University Press, Cambridge, United Kingdom and New York, NY, USA.
Lassen, C., Laugen, B. T. and Næss, P. (2006). Virtual mobility and organizational reality–a note
on the mobility needs in knowledge organisations. Transportation Research Part D: Transport
and Environment, 11(6), 459-463.
Lee, D.S., Fahey, D.W., Forster, P.M., Newton, P.J., Wit, R.C., Lim, L.L., ... & Sausen, R.
(2009). Aviation and global climate change in the 21st century. Atmospheric Environment,
43(22), 3520-3537.
Lohmann, M., Schmücker, D., Sonntag, U. (2014). German Holiday Travel 2025: Development
of Holiday Travel Demand in the German Source Market – The RA Trend Analysis. Kiel: FUR.
Marsden, G. and Rye, T. (2010). The governance of transport and climate change. Journal of
Transport Geography, 18(6), 669-678.
Nilsson, J.H. (2009). Low-cost aviation. In Gössling, S. and Upham, P. (eds) Climate Change
and Aviation. Earthscan, pp. 113-129.
OECD (2003). Environmentally Harmful Subsidies: Policy Issues and Challenges. OECD, Paris.
OECD (2012). Inventory of Estimated Budgetary Support and Tax Expenditures for Fossil Fuels
2013, OECD Publishing, DOI:10.1787/9789264187610-en
OECD (Organisation for Economic Co-operation and Development) (2005). Environmentally
Harmful Subsidies. Challenges for Reform. Paris: OECD.
OECD (Organisation for Economic Co-operation and Development) (2015). OECD Companion
to the Inventory of Support Measures for Fossil Fuels 2015. Available at:
http://www.keepeek.com/Digital-Asset-Management/oecd/energy/oecd-companion-to-the-
inventory-of-support-measures-for-fossil-fuels-2015_9789264239616-en#page1 Accessed 12
November 2015.
OECD (Organisation for Economic Co-operation and Development) and International Transport
Forum (2009). Policy instruments to limit negative environmental impacts from increased
international transport. Discussion Paper no. 2009.9. Available at:
http://www.internationaltransportforum.org/jtrc/discussionpapers/dp200909.pdf Accessed 12
November 2015.
OECD and UNEP (2011). Climate Change and Tourism Policy in OECD Countries. Paris:
OECD and UNEP.
Peeters, P. M., & Eijgelaar, E. (2014). Tourism's climate mitigation dilemma: flying between rich
and poor countries. Tourism Management, 40, 15-26.
Peeters, P. M., Gössling, S. & Becken, S. (2006). Innovation towards tourism sustainability:
climate change and aviation. Journal of Innovation and Sustainable Development, 1(3), 184-200.
Reilly, J., Paltsev, S., Monier, E., Chen, H., Sokolov, A., Huang, J., Ejaz, Q., Scott, J., Morris, J.
& Schlosser, A. (2015). Energy & Climate Outlook. Available:
18
http://globalchange.mit.edu/files/2015%20Energy%20%26%20Climate%20Outlook.pdf
Accessed 28 October 2015.
Schäfer, A., Heywood, J.B., Jacoby, H.D., & Waitz, I.A. (2009). Transportation in a climate-
constrained world. Cambridge: MIT Press.
Schmücker, D., Grimm, B., Wagner, P. (2015). Reiseanalyse 2015: Summary of findings –
Demand structure and trends in the German holiday market. Forschungsgemeinschaft Urlaub und
Reisen e.V. (FUR). Kiel
Scott, D., Gössling, S., Hall, C.M. and Peeters, P. (2015). Can tourism be part of the
decarbonized global economy? The costs and risks of alternate carbon reduction policy pathways,
Journal of Sustainable Tourism, DOI: 10.1080/09669582.2015.1107080
Sterner, T. (2007). Fuel taxes: an important instrument for climate policy. Energy Policy 35,
3194–3202.
Tollefson, J. (2016). UN agency proposes greenhouse-gas standard for aircraft. Nature 530, 266,
doi:10.1038/nature.2016.19336
T&E (2016). A false dawn for action on aviation emissions. Available at:
https://www.transportenvironment.org/newsroom/blog/false-dawn-action-aviation-emissions
Accessed 21 October 2016.
UBA (2016). Klima, Energie [Climate, energy]. Available at:
https://www.umweltbundesamt.de/themen/klima-energie Accessed 21 February 2016.
Ummel, K. (2014). Who Pollutes? A Household-Level Database of America’s Greenhouse Gas
Footprint. CGD Working Paper 381. Washington, DC: Center for Global Development.
UNESA (2015). World Population Prospects, the 2015 Revision. Available at:
http://esa.un.org/unpd/wpp/Download/Standard/Population/ Accessed 10 February 2016.
UNFCCC (2016). Various documents. Available: www.unfccc.int. Accessed 19 January 2016.
UNWTO (2011). Tourism Towards 2030. Global Overview. Madrid: UNWTO.
UNWTO (2015). Tourism Highlights 2015 Edition. Available at: http://www.e-
unwto.org/doi/pdf/10.18111/9789284416899 Accessed 17 February 2016.
von Rozycki, C., Koeser, H., & Schwarz, H. (2003). Ecology profile of the German high-speed
rail passenger transport system, ICE. International Journal of Life Cycle Analysis, 8(2), 83-91.