Why else are they missing

Why are other places in the world disappearing to me according to my studies in grade 9 one of the reasons for the loss of place in the world is climate change what is climate change ??

Climate change:

a change in the global or regional climate patterns, in particular a change that was seen from the mid-to-late 20th century onwards and attributed to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels.........

due to climate change the area is cool and some snow will gradually melt and cause the water level to rise and the water will cover the lands that are missing but we can avoid climate change if we will protect mother nature ...

(This is not detailed and this is only what I learned)