The problem does not just make life unpleasant for residents and visits less enjoyable for tourists, it also puts significant strain on the environment and is hurting the climate. So many people flying into the same place degrades local ecosystems and natural defences against the effects of climate change.

Overtourism has a profound and often devastating impact on the physical, social, and economic fabric of popular destinations. Physically, it leads to the degradation of historic monuments and natural ecosystems; for example, the delicate stone of the Acropolis or the coral reefs of Maya Bay suffer direct damage from millions of footsteps and pollutants. Socially, it causes the "hollowing out" of cities, as local residents are pushed out by rising rents and the conversion of long-term housing into short-term vacation rentals (the "Airbnb effect"). This leads to the loss of local culture, as traditional shops are replaced by souvenir stalls and global chains. Economically, while it brings in revenue, it often creates a "mono-economy" that is highly vulnerable to global shifts, and the sheer volume of visitors strains public infrastructure like sewage systems, waste management, and public transport beyond their design limits. Furthermore, it creates a hostile relationship between locals and visitors, leading to protests and restrictive laws, as seen in Venice or Barcelona, where the quality of life for permanent residents has declined significantly due to the sheer density of tourist crowds.