ameliorate - uh-MEEL-ee-oh-RATE - to make better, to improve
Example: "A Chilean earth group avowed (openly declared) that the USA could ameliorate environmental corruption by following President Obama's goal in nature preservation."
As a starter: and as a former teacher in English, I hope to add to reader's vocabulary by presenting a word a day in simple terms that anyone can understand - from current use in publications, radio,TV, etc. Remember: use a new word three times in a day and it's yours forever!