Study on the impact of carbon emission pollution on urban tourism environment

The tourism industry will continue to produce carbon emissions in the process of development, which will ultimately have an impact on the tourism environment. This article aims to study the effect of carbon emission pollution on the urban tourism environment. Taking Hebei Province from 2016 to 2020 as an example, the effect of carbon emission pollution on the local tourism environment was analyzed using the carbon emission model and tourism eco‐efficiency model. The local carbon emission increased in the process of developing the tourism industry; however, carbon emissions per unit in the accommodation, catering and shopping related to the tourism industry generated more tourism economic benefits. The authors suggest to strengthen the development of tourism transportation, increase local tourism promotion, enhance the diversity of tourism specialties, and improve the level of local catering and hotel services.


INTRODUCTION
The tourism industry develops by providing a high-quality tourism environment for tourists. 1 Under normal circumstances, the high-quality tourism environment will attract more tourists and industries such as transportation and accommodation that serve tourists. However, tourists will inevitably cause carbon pollution involving food, accommodation, transportation, waste, etc., to the environment in the process of playing. The most intuitive manifestation of the increase in carbon emission pollution is the increase in carbon dioxide emissions, which will eventually strengthen the greenhouse effect and cause various extreme weather conditions. The increase in carbon emission pollution and various extreme weather conditions will have a negative impact on the tourism environment 2 and reduce the quality of the tourism environment, which will make it less attractive to tourists. If the carbon emissions in the development of tourism are not controlled, then the vicious circle caused to the tourism economic environment will continue to increase, making it difficult to achieve sustainable development. By studying the impact of carbon emission pollution on the tourism economic environment, the sources of carbon emissions that affect the tourism environment can be identified, and targeted adjustments can be made to achieve sustainable development of the tourism economic environment. 3 This article briefly introduced the tourism carbon emission model and eco-efficiency model and made an example analysis of the tourism industry in Hebei Province from 2016 to 2020. The contribution of this article is that the carbon emission model and the eco-efficiency model were used to measure the effect of carbon emission pollution on the tourism environment. Some suggestions were proposed. This work provides an effective reference for improving the economic benefits brought by tourism environment.

LITERATURE REVIEW
Zha et al. 4 constructed an evaluation framework for direct and indirect CO 2 emissions from tourism and incorporated CO 2 emission factors into an efficiency evaluation framework based on the SBM model. They measured and analyzed the efficiency of low-carbon tourism economic development and its dynamic fluctuations in every city of Hubei, China, from 2007 to 2013. The results showed that the overall efficiency of the low-carbon tourism economy was low and differed significantly between different cities and production factors within the urban tourism economy system had untapped potential. Nabernegg et al. 5 analyzed a series of different policies in three areas where consumption-based emissions were particularly high in Austria: building construction, public health, and transportation. The results showed that the effectiveness of a policy to reduce consumption-based emissions depended on the backward and forward linkages of the sectors involved in the policy and substitution effects in final demand. Akbar et al. 6 used the factor analysis system SBM-undesirable model to calculate the agro-ecological output of each province separately based on 31 provincial panel data from 2007 to 2017 and calculated the ecological performance impacts using a carbon transfer network impact analysis panel. Adebanjo and Shakiru 7 studied the relationship between air pollution and economic development and found that there was a significant relationship between air pollution variables and economic growth and that economic growth had both positive and negative effects on air pollution. Moreno Rocha and Luis 8 conducted a study on water recycling utilization. They adopted Scopus database and text mining program VantagePoint to identify 425 records and finally found that 83% of them suggested an increasing trend of water recycling economy. A study by Maiwada and Ahmad 9 contributed to realizing lasting development in developed countries through academic and agricultural industry reports, development and commercialization operations.

CARBON EMISSION MEASUREMENT
In this study, a tourism carbon emission model 10 is constructed to calculate the carbon emissions generated to the environment in the tourism process, and the formula is In this study, the carbon emissions from tourism are classified into six types: tourism transportation, tourism accommodation, tourism catering, tourism activities, tourism shopping, and tourism waste in the established tourism carbon emission model. Tourism transportation contains external transportation, internal transportation, and transportation in the scenic area. Compared with external transportation, internal transportation is generally smaller in scale, so it is ignored. Transportation in the scenic area is generally used for facilitating the tourists' activities in the scenic area, so it is classified into tourism activities in the calculation.
Tourism accommodation refers to the act of resting of tourists when visiting a scenic spot for a long time. Different levels of carbon emissions will be generated depending on the bed and room occupancy rate included in the type of accommodation. Tourism catering refers to the different types of food consumed by tourists during the tour, and the carbon emissions generated from the production of consumed food are calculated. Tourism activities refer to sightseeing and recreation in scenic areas, and the energy consumed in tourism activities is converted into carbon emissions. Tourism shopping refers to the purchase of goods by tourists in scenic spots, and the carbon emissions from the production of goods are calculated based on the goods purchased. Tourism waste refers to the waste generated by tourists during their activities in scenic spots, and the carbon emissions from the disposal of waste are calculated based on the amount of waste. In Equation (1), TCF 1 is the carbon emission from tourism transportation, TCF 2 is the carbon emission from tourism accommodation, TCF 3 is the carbon emission from tourism catering, TCF 4 is the carbon emission from tourism activities, TCF 5 is the carbon emission from tourism shopping; TCF 6 is the carbon emission from tourism waste, and TCF is the total carbon emission in the tourism process.
In addition, in Equation (1), P i is the number of tourists on Class i vehicle, L i is the average mileage of Class i vehicle; i is the CO 2 emission factor per unit mile of Class i vehicle for each tourist; i is the equivalence factor for Class i vehicle emitting equivalent amount of CO 2 , B i is the number of beds in Class i accommodation place, l k is the CO 2 emission factor of the kth energy, BEC i is the energy consumption per bed per day in Class i accommodation place, N is the number of tourists in tourism activities, D is the number of days of stay per tourist while traveling, FC i is the average consumption amount of Class i food per tourist per day, ED i is the energy density in Class i food, 11 i is the proportion of tourists participating in Class i tourism activity, AEC i is the energy consumption per tourist in Class i tourism activity, CQ i is the average amount of Class i commodity bought by every tourist, i is the CO2 convert coefficient of Class i commodity, 12 Q SW is the amount of solid wastes generated by every tourist per day in the tourism process, E 1 is the unit energy consumption for solid waste treatment, Q D is the amount of sewage generated by every tourist per day in the tourism process, and E 2 is the unit energy consumption for sewage treatment.

TOURISM ECO-EFFICIENCY
Eco-efficiency first appeared in ecology and was used to express the utilization of solar energy or the energy available at the previous trophic level by organisms at different trophic levels in an ecosystem. Subsequently, in order to quantify sustainable development, the concept of eco-efficiency was used to quantitatively evaluate the effects of sustainable development from both economic development and environmental protection perspectives. 13 Tourism eco-efficiency has some similarities with eco-efficiency. In the quantitative evaluation of the sustainable development of the tourism industry, the evaluation is also made from perspectives of environmental protection and tourism economy. The development policy is adjusted according to the evaluation results to improve tourism eco-efficiency. 14 The expression formula of the tourism eco-efficiency model is: where TEE 1 , TEE 2 , TEE 3 , TEE 4 , and TEE 5 are the eco-efficiency of transportation, accommodation, catering, activities, and shopping in tourism, respectively, TEE is the total eco-efficiency of the tourism industry, TI 1 , TI 2 , TI 3 , TI 4 , and TI 5 are the revenue of transportation, accommodation, catering, activities, and shopping in tourism, respectively, and TI is the total revenue of tourism. 15

Overview of the study area
Hebei, abbreviated as "Ji", is a provincial administrative region in China. It geographically locates in North China and surrounds the capital Beijing. Hebei, bordered by the Bohai Sea to the east, the Taihang Mountains to the west, and the Yanshan Mountains to the north, is the only province in China that combines highlands, mountains, hills, plains, lakes, and seashores. Hebei Province has a temperate continental monsoon climate. 16

Data collection
This article mainly used the carbon emission model and the tourism eco-efficiency model to analyze the impact of carbon emission pollution on tourism environment. A large amount of data was needed to support the analysis. If the data collection scope is extended to the whole country, although enough data can make the analysis more in-depth, it will also increase the amount of computing, so considering the difficulty of data collection, we finally chose the data of Hebei Province from 2016 to 2020. The data required for the calculation and analysis of tourism eco-efficiency in Hebei Province in this study are mainly from Hebei Province Statistical Yearbook (2016-2020), 17 Hebei Province Tourism Market Research (2016-2020), and the Hebei Province tourism government website. The data mainly included the number of tourists and tourism income in Hebei Province between 2016 and 2020, the average length of stay of tourists, the number of beds in different levels of accommodation and the occupancy rate, and the proportion of tourists' expenditure on travel tools, food, accommodation, activities and shopping during the tour. In addition to the above basic data, this study further investigated the prices and sales of goods at tourist attractions through actual surveys and official websites; for tourist transportation, the distance traveled and the number of times used by different types of transportation used during tourism were further investigated through map software, airlines, bus companies, and railroad service centers. 18

Analysis results
In this study, the carbon emissions of different items in the tourism industry in Hebei Province were calculated by collecting relevant data from the tourism industry in Hebei Province and substituting them into the tourism carbon emission model. The calculation results from 2016 to 2020 are shown in Table 1 and The carbon emissions in different items of the tourism industry were analyzed. It was seen from Figure 1 that among the six sources of carbon emissions from the tourism industry, transportation had the highest carbon emissions, followed by carbon emissions from tourism activities, and there was a large difference between them; wastes from tourism has the lowest carbon emissions among the six sources. Then, the carbon emissions of different years under the same carbon emission item were compared. It was seen from Figure 1 that the carbon emission of transportation, accommodation, catering, activities and shopping were increasing year by year, the overall proportion of carbon emissions from waste was too small to be obvious in Figure 1, but the change of values in Table 1 showed that the carbon emissions from waste were also increasing year by year. The tourism eco-efficiency model was combined with carbon emissions calculated by the carbon emission model to calculate the tourism eco-efficiency of Hebei Province from 2016 to 2020, and the results are shown in Table 2 and The tourism eco-efficiency of different items in the tourism industry was analyzed. It was seen from Figure 2 that the tourism eco-efficiency of tourism transportation was increasing year by year, although the magnitude was relatively small; the tourism eco-efficiency of tourism accommodation increased year by year from 2016 to 2018, but decreased significantly in 2019 and 2020; the difference in the tourism eco-efficiency of tourism catering from 2016 to 2018 was not large, but there was a significant increase in 2019 and 2020; the tourism eco-efficiency of tourism activities increased year by year; the tourism eco-efficiency of tourism shopping showed a trend of decreasing year by year; the difference of the total tourism eco-efficiency was not large.

DISCUSSION AND RECOMMENDATIONS
In calculating carbon emissions, although the increase of carbon emissions of different tourism items was different, they all increased year by year. The main reason for the above result is that the development of the tourism industry gradually attracted tourists, and the increase of the number of tourists made the industries related to the tourism industry also increased. The carbon emission of tourism transportation was the largest among all the tourism carbon emission items, indicating that transport facilities of the tourism industry had the largest impacts on the environment. In addition, the carbon emissions from tourism transportation were increasing year by year because the number of tourists was increasing year by year due to the development of the tourism industry, more tourists were choosing transportation modes such as self-driving cars or airplanes due to the pursuit of comfort, and burning gasoline used in airplanes and cars generated large amounts of carbon dioxide to pollute the atmosphere. The carbon emissions of tourism accommodation grew year by year, but the growth rate gradually slowed down. The reason for the above result is as follows: The development of the tourism industry attracted more tourists to stay in hotels, and the increase of beds made the total carbon emission increase, but the increased beds were usually from small hotels with lower energy consumption, and tourists were more inclined to stay in small hotels with lower price. The carbon emission pollution brought by accommodation came from the beds and the consumption of water, electricity and gas by the equipment matching with the beds. The use of natural gas directly generated carbon dioxide pollution to the atmosphere, and thermal power generation generated carbon dioxide pollution to the environment.
The reason for the increase of carbon emission from tourism catering is that tourists preferred high energy-density food with high CO 2 emissions such as meat, eggs and milk when they travel in Hebei Province, while low energy-density food with low CO 2 emissions such as vegetables, melons and fruits were not attractive enough to tourists. The carbon emission pollution brought by catering came from the consumption of water, electricity and gas in the process of producing these foods as carbon dioxide generated in this process caused pollution to the environment. The carbon emissions from tourism activities were increasing year by year, but the magnitude was gradually decreasing. The reason is that the number of tourists has increased, but more and more tourists preferred low-carbon tourism that is more relaxing and close to nature. The carbon emissions from tourism activities came from the various equipments used in the process of activities, especially the electricity and fossil fuels-driven equipment, which directly produced carbon dioxide to pollute the environment.
The carbon emissions from shopping were increasing year by year, but the magnitude was decreasing. The development of the tourism industry made the number of tourists increase; therefore, the shopping volume increased. The decreased increase is because increased access to local specialty products made tourists less willing to buy locally. The carbon emissions from shopping are indirect as goods produce carbon emissions in the production process. The increase in carbon emissions from waste is due to the increase in tourists and the increase in the length of stay in tourist attractions. The carbon emissions from waste come from the energy consumption in the disposal of waste. If incineration is used, carbon dioxide will be produced to pollute the environment.
In the calculation results of tourism eco-efficiency in Hebei Province, the tourism eco-efficiency of accommodation, catering and shopping was significantly higher than the total tourism eco-efficiency, and the tourism eco-efficiency of transportation and activities was lower than the total tourism eco-efficiency, indicating that accommodation, catering and shopping pull the tourism economy when the development of the local tourism industry causes per unit impact on the local environment, but transportation and activities had a hindering effect. The tourism eco-efficiency of tourism accommodation significantly decreased in 2019 and 2020 because the regulations carried out by the government on public spending made the bed occupancy rate of high-class hotels that originally received official business greatly reduced, but the maintenance of bed facilities still had to be carried out and generated carbon emissions, resulting in constant carbon emissions but increased economic income. The tourism eco-efficiency of catering was on the rise. The increase in the number of tourists and the improvement in living standards made tourists more willing to experience some high-class catering, but although the class was improved, the food consumption was essentially constant, making the carbon emissions nearly unchanged. But the income increased, leading to an increase in tourism eco-efficiency. The tourism eco-efficiency of shopping decreased year by year because of the serious price premium of commodities in tourist attractions. Low purchase intention of tourists reduced economic income and consequently reduced tourism eco-efficiency.
The tourism eco-efficiency of activities increased. The reason is as follows. Tourists had a greater ability and willingness to pay for tourism activities; therefore, economic incomes from tourism activities were higher. In addition, the activities that tourists had a higher willingness to pay for were usually low-carbon activities that can relax. The reason for the increase in tourism eco-efficiency of transportation is as follows. The technological development of rail transportation has greatly improved its transportation efficiency. Although the energy consumption per unit time has increased, the overall energy consumption has not changed much because of the reduced transportation time; however, the higher transportation efficiency provided more transportation volume in the same transportation time and thus improved the economic benefits.
Based on the results of the above analysis, the following recommendations are proposed to enhance tourism eco-efficiency and minimize the impact of carbon emission pollution on the local tourism economy and environment.
1. The tourism eco-efficiency of transportation can be improved by increasing the discount on public transportation in the tourism industry, improving the quality of services for group travel, and encouraging tourists to travel in groups using public transportation and reduce the use of self-driving cars. 2. Hebei Province should strengthen the promotion of local tourist attractions to increase tourists' interest in various activities at tourist attractions to improve the economic output of activities at attractions and enhance the tourism eco-efficiency of activities. 3. Hebei Province should improve the diversity of specialty products in local tourism and reduce product homogeneity to increase tourists' interest in buying and prevent the reduction of tourism eco-efficiency of shopping. 4. The tourism industry should adjust the structure of vegetables and meat for tourists and improve the characteristics and quality of catering to make tourists choose vegetarian dishes with low energy consumption, so as to improve the tourism eco-efficiency of catering. 5. Hebei Province should enhance the service quality of non-premium hotels, encourage tourists to stay in low-carbon hotels, and regulate the size of premium hotels to enhance bed utilization, so as to improve the tourism eco-efficiency of accommodation.

CONCLUSION
This article briefly introduces the tourism carbon emission model and eco-efficiency model and makes an example analysis of the tourism industry in Hebei Province from 2016 to 2020. The results demonstrated that the development of tourism increased carbon emissions, especially transportation; accommodation, catering and shopping in the tourism industry in Hebei Province pulled more economic development per unit of carbon emissions. Finally, several recommendations are proposed based on carbon emissions and tourism eco-efficiency. The limitation of this article is that only data related to Hebei Province from 2016 to 2020 were selected for the example analysis, which is limited in the size of the region and time span. Future research directions include expanding the scope of the study area and increasing the length in time.

CONFLICT OF INTEREST STATEMENT
The author declares that there is no conflict of interest.