Definition: In this task, you are given a statement spoken by a politician in natural language. Your task is to generate the subject of the discussion for the given statement. The subject generated is not necessarily a part of the given input. Your answer should contain one or more words.
Input: For several days in July of 2012, Greenland surface ice cover melted more than at any time in 30 years of satellite observation. During that month, an estimated 97% of the ice sheet thawed.

environment