deforestation vs desertification

deforestation

noun
  • The process of destroying a forest and replacing it with something else, especially with an agricultural system. 

  • A transformation to eliminate intermediate data structures within a program. 

desertification

noun
  • The process by which a geographic region becomes a desert, resulting from natural changes in climate or by human activity. 

How often have the words deforestation and desertification occurred in a corpus of books? (source: Google Ngram Viewer )