ice sheet - n. a very large and thick area of ice that covers a region

pace - n. the speed at which someone or something moves

frequency - n. the number of times that something happens during a particular period

global - adj. involving the entire world

El Niño - n. a flow of unusually warm water along the western coast of South America that causes many changes in weather in other places (such as a lot of rain in areas that are usually dry)