What term is used to describe the clear-cutting of rain forests for their valuable lumber, which often results in species loss?

The answer for the above question is Deforestation. It involves the removal of trees in large quantities at a time. It affects the atmosphere in a couple of ways which includes; Trees remove carbon dioxide from the air and thus they reduce the amount of CO2 that gets into the atmosphere, acting as global warming. Deforestation causes a release of large amounts of Carbon dioxide in the air through burning of fuels, since there are no trees to remove it. 

When scientist examine data such as historical documents, they are using the "scientific methods"