Most environmental experts believe _____________that Response area is the leading environmental problem we currently face. Today, the leading cause of the destruction of natural habitats is___________ Response area activity. As the human Response area grows, so does the need for more goods and natural Response area. Increased Response area is caused by the expansion of Response area land needed to grow crops, the harvesting of Response area as building materials, the need for wood as a source of Response area, and clear-cutting land for grazing animals (i.e., Response area). One report showed that over Response area of the world's land was being used for farming.