Mother Nature is the personification of nature itself, and has the task of nurturing those on Earth.
On the Earth Day of April 22, 1990. Mother Nature had fallen ill due to the years of pollution on the planet. She was taken to St. Terra Hospital at the town square of Anytown, where she was kept under the care of several physicians, including Doogie Howser.
Dr. Emmett Brown arrived shortly to check up on her, as well as showing the doctors the current condition of the planet and the last of the rainforests ceasing to exist by 2057. He returned later to share information from the library on how she could be saved through bettering The Earth.