Test your knowledge with these top questions!
Why do many Arctic buildings stand on raised pilings above permafrost?
Building heat can thaw frozen soil, so pilings keep structures stable while cold air flows beneath.
Which slow changes trigger ice age cycles over thousands of years?
Small wobbles in tilt and orbit change sunlight and grow or melt large ice sheets.
Which floating shelf forms the largest extension of the Antarctic Ice Sheet?
The Ross Ice Shelf spans an area roughly the size of France and feeds ice into the ocean.
In permafrost ground, what is the seasonally thawed surface layer called?
The active layer freezes and thaws yearly, so plants root there while deeper ground stays frozen.
Permafrost is ground that stays frozen for at least how long?
Scientists classify ground as permafrost only after it stays at or below freezing for two straight years.
Which warm Atlantic current feeds the ocean conveyor warming Western Europe?
The Gulf Stream sends warm surface water north, where cooling and salt make the water sink and return south at depth.
Which chemicals in old spray cans damaged the ozone layer?
Chlorofluorocarbons release chlorine high in the air, and each chlorine atom can destroy many ozone molecules.
Which satellite mission weighed Greenland Ice Sheet losses with gravity data?
The twin GRACE satellites sensed tiny gravity shifts as Greenland shed hundreds of billions of tons in many recent years.
If the Greenland Ice Sheet melted fully, seas would rise about how much?
Greenland holds the second-largest ice volume on Earth, far below the Antarctic total near 60 meters.
The Greenland Ice Sheet blankets most of the world's largest what?
Greenland is the world's largest island, with about four-fifths buried under ice.