Do economic development and tourism heterogeneously influence ecological sustainability? Implications for sustainable development.

While economic development-driven anthropogenic emissions pose challenges to ecological sustainability, the international travel and tourism sector has appeared as a hot contestant to bring sustainability to the ecological systems across varying development levels. This work investigates the diversified effects of the international travel and tourism sector and economic development on ecological deterioration, in the presence of urban agglomeration and energy use efficiency, across the development levels of China's 30 provincial units from 2002 to 2019. It contributes in two ways. (i) The stochastic estimation of environmental impacts by regression on population, affluence, and technology (STIRPAT) is modified to integrate the variables like international travel and tourism sector, urban agglomeration, and energy use efficiency. (ii) We measured an international travel and tourism sector index (ITTI) and made use of a continuously updated bias correction strategy (CUBCS) and a continuously updated fully modified strategy (CUFMS) for the long-term estimations. Besides, we used the bootstrapping-based causality technique for determining causality directions. The core results are as follows: Firstly, ITTI and economic development produced an inverse U-type association with ecological deterioration for the aggregate panels. Secondly, provinces exhibited a diverse range of links in that ITTI mitigated (boosted) the ecological deterioration in eleven (fourteen) provinces presenting diversified shapes of linkages. Economic development established the environmental Kuznets curve (EKC) theory with ecological deterioration in merely four provinces; however, the non-EKC theory is verified in twenty-four divisions. Thirdly, in China's east zone (high development scale), the ITTI revealed the ecological deterioration reduction (promotion) impact in eight (two) provinces. China's central zone (moderate development scale) exhibited ecological deterioration promotion in half of the provinces, and the other half showed a reduction impact. In China's west zone (low development scale), it promoted ecological deterioration in eight provinces. Economic development promoted (reduced) ecological deterioration in a single (nine) province(s). In China's central zone, it boosted (mitigated) the ecological deterioration in five (three) provinces. In China's west zone, it promoted (reduced) ecological deterioration in eight (two) provinces. Fourthly, urban agglomeration and energy use efficiency deteriorated and improved the environmental quality in aggregated panels, respectively; however, a diverse range of effects are observed for provinces. Finally, a unilateral bootstrap causality, from ITTI (economic development) to ecological deterioration, is revealed in twenty-four (fifteen) provinces. A bilateral causality is established in a single (thirteen) province(s). Based on empirical findings, policies are suggested. Highlights: • Calculated international travel and tourism sector index (ITTI). • Employed wastewater emissions (WWE) to proxy for ecological deterioration. • ITTI and economic development had an inverse U-shape with WWE for aggregate panels. • Highest developed provinces had WWE discounting effect with inverse U-shape. • Lowest developed provinces had WWE promotion effect with diverse shapes. • Overall, unidirectional causality from ITTI and economic development to WWE. [ABSTRACT FROM AUTHOR]