20 places you should visit before they disappear

Earth is home to incredibly beautiful natural sites.

Unfortunately, due to climate change and human carelessness, some of them are in danger of disappearing in the next 100 years - or even sooner.

In honor of Earth day, we found 20 places all travelers should see while they still exist. From ancient Mayan ruins in Guatemala to the Swiss alps, these threatened natural wonders span the globe.