How have humans changed the environment?

Humans have changed the environment by developing science step by step and using it the wrong way.Man is the world's greediest animal and for his greed and selfishness he did everything possible for himself and didn' care for any other life forms.He wanted more and more comforts and luxuries.For tHAT HE CUT TREEES AND GRADUALLY THE ENVIRONMENT CHANGED.DEFORESTATION IS THE MAIN CAUSE OF ALL THE -PROBLEMS ON THE EARTH.