(a) Deforestation: Enormous quantity of wood was used in the first civilisation to produce bronze. Jewellery was also made by wood. Wood was needed to bake bricks, pottery, stoneware and to make boats and furniture. These activities lead to deforestation resulting in changes in the climate.
(b) Earthquake: Earthquakes caused changes in the course of the Indus river which led to the inundation of the hinterland of Mohenjo-daro