**1. Introduction**

Anthropogenic activities such as deforestation and burning of fossil fuels produce a large amount of greenhouse gases, and the continued increase in carbon dioxide emissions is expected to have a catastrophic impact on the global climate system. Therefore, it has become the consensus of various countries around the world to mitigate the negative impacts of climate change and ensure sustainable development by continuously reducing carbon emissions [1]. The United Nations Environment Programme (UNEP) proposed in 2011 that a green economy can improve human well-being and social justice and that it can serve as a pattern for building a resource-efficient and environmentally friendly society. It is also an important way to promote sustainable development and aid in poverty eradication. Since its reform and opening up, China's economy has grown at a rapid rate of 9.7% per year [2], rapidly becoming the world's second largest economy, ranking among the upper middle-income countries and lifting 800 million people out of poverty [3]. However, China's economic development still has serious problems due to the widespread use of energy that exploits the environment to promote economic growth. According to the World Bank, China has become the world's largest energy consumer. China accounts for 27.6% of the world's CO2 emissions [4], and the Chinese government has committed to ensure that carbon emissions peak by 2030. Thus, the Chinese government has recognized that current and potential environmental degradation poses a serious threat to China's sustainable development and that the previous aggressive development model is no longer

**Citation:** He, X.; Shi, J.; Xu, H.; Cai, C.; Hu, Q. Tourism Development, Carbon Emission Intensity and Urban Green Economic Efficiency from the Perspective of Spatial Effects. *Energies* **2022**, *15*, 7729. https:// doi.org/10.3390/en15207729

Academic Editors: Junpeng Zhu and Xinlong Xu

Received: 16 September 2022 Accepted: 17 October 2022 Published: 19 October 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

<sup>1</sup> Tourism College, Hunan Normal University, Changsha 410081, China

appropriate. Solving China's problems will not only benefit the quality of China's economic development but also provide a model in balancing economic growth and the environment that could be used by other developing countries around the world. However, based on economic stability, ensuring the achievement of this goal is an important challenge for the Chinese government, and improving economic efficiency is certainly an effective way of achieving it [5]. For European countries, tourism, as a key sector of the European economy, is an important source of income and employment in Europe [6]. However, carbon intensity in Europe is growing steadily. Therefore, these countries must also mitigate carbon emissions through tourism reforms [6]. It can be seen that both developing and developed countries are actively seeking a balance between energy consumption and economic growth, exploring the carbon reduction effect of the tourism industry, the green economy effect and its interaction, so that the research results can become a guide to the reality of the dilemma between tourism and environmental protection.

In the economic sense, economic efficiency usually refers to how to obtain as much output of economic goods from as few factor inputs as possible, mainly considering the input–output ratio of labor and capital inputs [7]. In 2010, Yang and Hu first proposed green economic efficiency as a key indicator to measure the level of the green economy, and green economic efficiency further addresses the issues of energy constraints and undesired output [8]. Therefore, green economic efficiency can be defined as an economic production system that can achieve greater economic output or less environmental pollution with constant or reduced factor inputs, taking into account the constraints of resources and the environment [5,9,10]. For studies of green economy efficiency, data envelopment analysis (DEA) is a common method used by most scholars [11–16]. However, DEA is either inputor output-oriented and cannot consider both output and input, which is a limitation of the DEA measurement method. To avoid such problems, some scholars use the slack-based measurement (SBM) method to measure green economic efficiency [5,17–23]. Although the SBM model achieves a balance of inputs and outputs, it also ensures different proportional changes in inputs and outputs, which are closer to the true values [5]. However, the SBM model cannot solve the problem of undesired outputs. In recent years, the EBM method has been increasingly used by scholars to study energy efficiency or environmental efficiency [24–28]. Therefore, this paper adopts the EBM model to measure the green economy efficiency level of 280 prefecture-level cities in China.

It is widely acknowledged that the tourism industry makes a significant contribution to economic development in terms of income generation, tax revenue and employment [29]. After reform and opening up, tourism has developed along with China's economic takeoff, and it has become a pillar industry of China's economy. According to data from the China Tourism Research Institute, the number of domestic tourists rose from 2.13 billion to 6.006 billion from 2010 to 2019, and the total revenue from tourism rose from 1.57 trillion RMB to 6.63 trillion RMB. This rise in tourism is not only the case in China; the tourism industry is also a key sector of the European economy, prioritized by the EU as an important source of income, employment and economic growth [6]. As the contribution of tourism agglomeration increases, scholars are increasingly looking at the relationship between tourism development and economic growth [6]. During the continuous development of tourism, the carbon emissions generated by the activities of tourism itself, such as transportation, accommodation and catering [30], as well as tourism-related industries [31], have gradually increased. For countries or regions with large populations or developed tourism industries, the relationship between tourism and carbon emissions has received much attention [32], for example, in China [33], the European Union [6] and Southeast Asia [32].

Compared with other industries, tourism is less polluting, less ecologically damaging and less energy-consuming, which are hallmarks of a typical green industry and demonstrate that it contributes to the development of the green economy in cities [34]. Therefore, based on the uniqueness of tourism, the relationship between tourism development, carbon emissions and economic growth has been a hot topic of research [6,32,35–42]. After the

introduction of the concept of the green economy, what is the relationship between tourism as a green industry and carbon emissions and the green economy? Is there a necessary link between tourism development, carbon emissions and a green economy? As cities become more frequently and closely connected, the development of neighboring cities is mutually linked and influenced, so it is necessary and important to consider spatial effects. Furthermore, with the global advocacy for green development, it is crucial to understand the relationship between urban tourism development, carbon emission intensity and green economic efficiency. This is not only important for China to achieve the goal of reducing carbon emissions but also has important practical significance for the global exploration of green economic development paths.

The contribution of this paper may be as follows. First, the article defines the relationship among tourism development, carbon emission intensity and green economic efficiency. Supported by the data of 280 prefecture-level cities in China from 2007–2019, this paper confirms that urban tourism development has a significant positive effect on the reduction in carbon emission intensity and the improvement of green economic efficiency. Meanwhile, it confirms that carbon emission intensity plays a significant mediating role in the promotion of urban green economic efficiency by tourism development. Second, this paper compares the spatial relationship between tourism development on carbon emission intensity and green economic efficiency. By using the spatial Durbin model and introducing spatial effects, this paper confirms that tourism development has a significant spatial spillover effect on the mitigation of carbon emission intensity and the improvement of green economic efficiency. On this basis, this paper tests the robustness of the spatial spillover effect of tourism development on carbon emission intensity and green economic efficiency by introducing the "low carbon city" pilot policy as an exogenous shock. Third, the paper compares the nonlinear characteristic relationship of tourism development on carbon emission intensity and green economic efficiency. Based on the previous influence relationship, this paper further explores the nonlinear characteristic relationship of tourism development on the reduction in carbon emission intensity and the improvement of green economic efficiency and elaborates the influence of tourism development on carbon emission intensity and green economic efficiency.

In order to introduce the research of this paper more clearly, the main contents of each chapter are introduced in the form of flowcharts in the order of the research catalog of this paper, as shown in Figure 1. The literature review and research hypotheses are given in the next section. The econometric methodology and model utilized in this study are provided in section three. Section four addresses the empirical results, and the last section provides a discussion of the findings together with policy implications.

**Figure 1.** Flow chart.

#### **2. Theoretical Foundations and Research Hypotheses**

Although there is no unified academic definition of the green economy, scholars have recognized that achieving a positive interaction between economic growth and the ecological environment is the core connotation of green economic development [14,43]. The tourism industry is inextricably linked to the regional economy, both in terms of GDP contribution and employment contribution [6,36], and plays an important role in promoting economic development. In addition, the tourism industry is both dependent on the destination's ecological environment and protective of it. A good ecological environment improves the quality of the elements of tourism development, while tourism development further protects the local ecological environment and realizes the sustainable development of the regional ecology. From the core connotation of the green economy, the impact of tourism development on the green economy is mainly reflected in two aspects [44,45]: ecological and environmental effects and economic growth effects.

In the process of tourism development, it will have direct and indirect effects on the local economy and environment, which will affect the level of local green economic efficiency. As shown in Figure 2, tourism development and environmental pollution have an "EKC" effect, i.e., the environmental Kuznets curve is introduced into tourism development, and the two are found to have an "inverted U" curve relationship [32]. At the same time, tourism development has both positive and negative environmental

externalities. The positive environmental externality refers to tourism as a friendly industry that does not involve industrial pollution [46] and has a significant carbon reduction effect [6]. The negative environmental externality, on the contrary, refers to the highcarbon nature of the tourism industry, which is a major contributor to greenhouse gas emissions [47]. Although it is recognized that the tourism industry itself has significant economic driving power [6], Corden et al. found that tourism development has a "Dutch disease" effect, i.e., tourism development promotes economic growth in the short term, but depresses the economy in the long term [48]. Based on the "Dutch disease" effect, scholars have shown that tourism development has a non-linear effect. More specifically, different levels of tourism specialization can have differential effects on economic growth [49]. These studies demonstrate that tourism development has a direct effect on economic efficiency and thus on green economic efficiency.

In addition to the direct impact, tourism development can also indirectly affect the efficiency of the green economy by influencing environmental and economic factors. Tourism development can optimize the ecological environment, industry linkage and integration, technological innovation and industrial structure. Tourism needs an excellent natural environment, so the development of tourism will inevitably require the relocation and withdrawal of highly polluting enterprises, performing a passive adjustment of industrial structure. In conclusion, environmental friendliness and economic growth are the core concepts of the green economy, tourism development in the process directly and indirectly affecting the local ecological environment and economic growth, with practical benefits and results to illustrate the existence of overlap between tourism development and green economic efficiency.

In terms of environmental benefits, the "environmental Kuznets" effect of tourism development is obvious [50], as the tourism industry produces environmental pollution such as waste gas and wastewater in the process of development, causing certain negative impacts on the ecological environment, but the economic growth effect brought by tourism development directly "compensates" by allowing environmental protection. In terms of indirect effects, tourism development can force the original industrial structure to be adjusted and optimized through the "crowding-out effect". In addition, the "dependency" of the local economy on the tourism industry raises the environmental awareness of the government and residents, creating formal and informal monitoring of the ecological environment and further optimizing the development environment. At the same time, tourism development also brings economic growth. For example, tourism development can directly lead to increased GDP and employment in cities and contribute to poverty alleviation in the destination. Moreover, the increasing integration of tourism with other industries not only facilitates the innovation and transfer of technology but also has a positive impact on the optimization of the industrial structure and market environment [21].

**Hypothesis H1:** *The impact of tourism development on the green economic efficiency of cities has a spillover effect.*

**Hypothesis H2:** *The impact of tourism development on urban green economic efficiency has a nonlinear relationship.*

The impact of tourism development on urban carbon emission intensity is mainly studied from the perspective of tourism industry agglomeration, and the environmental effect of tourism carbon emission reduction is mainly realized through externalities, which is a proven consensus [6,31,32,51]. The research on the relationship between tourism development and carbon emissions is mainly based on the environmental Kuznets curve hypothesis (EKC) proposed by American economists Grossman and Krueger. This hypothesis suggests that environmental quality deteriorates and then improves as the level of economic development increases, and there is an inverted "U" shaped relationship between environmental quality and economic development. The environmental effect brought by the development of the tourism industry is mainly studied from the two perspectives of the tourism economy and industrial agglomeration. On the one hand, the growth of the tourism economy follows the environmental Kuznets curve hypothesis, with a nonlinear characteristic relationship between the two [32], but at the same time, some scholars question this and test the relationship between the tourism economy and the decoupling of carbon emissions [33]. On the other hand, in the early stage of tourism industry agglomeration, the industry development method is relatively crude, and large-scale enterprises may be concentrated in the same area. Although this increases the regional GDP, as a process with fierce competition, it can also easily waste resources and energy and lead to a negative impact on the ecological environment [52]. As the level of agglomeration increases, the agglomeration of the tourism industry brings about a reduction in the cost of raw material transportation and transaction, a saving in energy and resources, and the agglomeration of enterprises with backward and forward linkage makes the exchange of knowledge and technology more convenient. The exchange and cooperation between tourism and other industries are likely to collide with new technologies, expand knowledge and technology spillover effects, and achieve synergistic innovation in technology, which in turn have a suppressive effect on carbon emissions and improve environmental pollution [6].

**Hypothesis H3:** *The impact of tourism development on urban carbon emission intensity has a spillover effect.*

**Hypothesis H4:** *The impact of tourism development on urban carbon emission intensity has a nonlinear relationship.*

Tourism development must both reduce carbon emissions and increase the GDP: on the one hand, tourism development needs to pay attention to reducing carbon dioxide emissions, both from tourism itself and from the manufacturing sector. According to existing research, tourism is not only highly correlated with manufacturing but also has a certain "crowding-out effect" on regional manufacturing [46]. Therefore, while developing tourism, clean energy should be used to reduce air pollution, thus attracting more tourists and generating more tourism revenue. This is also a mutually reinforcing process, as the development of tourism to a certain extent squeezes out the high-pollution manufacturing industry, which also alleviates regional carbon intensity. The ability of cities to reduce carbon emissions in turn directly affects the development of the urban green economy, and carbon emission intensity has a direct negative impact on the improvement of the urban green economy efficiency level [5,53,54]. Tourism development tends to consider the effect of its carbon emissions while influencing the efficiency of the urban green economy, which shows that carbon emissions have a very important role in the green development of tourism.

**Hypothesis H5:** *Carbon emission intensity has a mediating effect on the relationship between tourism development and urban green economic efficiency.*
