The average global temperature has increased by almost 0.5 centigrade degree over the past century, scientists expect it to rise by an extra 1～3 degrees over the next 100 years.

　　Warmer weather makes glaciers (冰川) melt, adding more water to the ocean. The warmer temperatures also make water expand, so it takes up more space, causing the sea level to rise. The sea level has risen about 10～25cm in the last 100 years.