Massive amounts of tourists ruin the sand, which acts as a buffer zone. If the buffer zone is ruined, waves will hit nearby human settlements, causing massive amounts of damage. As the globe's temperature rises, more and more waves will hit the populated zones, killing many people and forcing the others to leave. Eventually, the rest of the nation's citizens will be hard pressed to support all the orphans and refugees that need to be housed, fed, and clothed. This will lead to more limited resources and some unsanitary conditions, making the population's overall health lower. Also, tension would arise, leading to possible civil war. If the nation's leaders were smart, they'd know that they have to focus all the country's tension on an outside factor, possibly a country with ample resources. This would lead to a massive military build-up and eventual war, killing more men, women, and children. All this would occur while carbon build-up still continues. Once the war is over, people would go back to polluting and sitting at the beach during summer. In a decade or two, the process would repeat itself.
This is why beaches should be closed during the summer.
