Humans have had significant effects on the environment for thousands of years. For example, the deforestation of Easter Island or of many areas of ancient Greece and the Roman Empire occurred long before the Industrial Revolution. However, the Industrial Revolution accelerated the pace of anthropogenic climate change.
The first major effect the Industrial Revolution had on the environment was caused by the increased use of fossil fuel, first coal and then oil. The effects of this were twofold. First, there was increased mining and drilling and second a dramatic increase in the production of green house gasses.
The Industrial Revolution, and the accompanying improvements in agricultural productivity, led to a dramatic increase in the human population, causing humans to expand into what was previously wildlife habitat.
The most dramatic overall effect is what some scientists have labeled the dawn of the "anthropocene", a period in which humans affect their environment as much as their environment affects them.