Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snowremains in one location long enough to transform into ice. What makes glaciers unique is their ability to flow. Due to sheer mass,glaciers flow like very slow rivers. Some glaciers are as small as football fields, while others grow to be dozens or even hundreds ofkilometers long. Presently, glaciers occupy about 10 percent of the world's total land area, with most __71__ in polar regions likeAntarctica, Greenland, and the Canadian Arctic. Glaciers can be thought of as remnants from the last Ice Age, when ice covered nearly32 percent of the land, and 30 percent of the oceans. Since the early 1900s, many glaciers around the world have been rapidly melting. Human activities are at the __72__ of thisphenomenon. Specifically, since the industrial revolution, carbon dioxide and other greenhouse gas emissions have raised temperatures,even higher in the poles, and __73__ , glaciers are rapidly melting, calving off into the sea and retreating on land. Scientists projectthat if emissions continue to rise unchecked, the Arctic could be ice free in the summer as soon as the year 2040 as ocean and airtemperatures continue to rise rapidly.__ 74__ glaciers add to rising sea levels, which in turn increases coastal erosion and elevates storm surge as warming air andocean temperatures create more frequent and intense coastal storms like hurricanes and typhoons. Specifically, the Greenland andAntarctic ice sheets are the largest contributors of global sea level rise. Right now, the Greenland ice sheet is__ 75__ four timesfaster than in 2003 and already contributes 20% of current sea level rise. How much and how quickly these Greenland and Antarctic icesheets melt in the future will largely determine how much ocean levels rise in the future. Alarmingly, if all the ice on Greenland melted,it would raise global sea levels by 20 feet.
【題組】71.
(A) locate
(B) locating
(C) located
(D) to locate