The ice sheets in Greenland melt slightly during the summer months. This water collects in huge open lakes which eventually drain through Moulins. Moulins are

1. trenches along the surface of the glacier which direct the water towards the ocean.
2. huge water falls which allow the water to fall thousands of feet towards the bed rock underlying the glacier.
3. are huge open collecting pools which allow the water to slowly evaporate.
4. are pumps which pump the water uphill to huge tanks which provide water for the people of Greenland.

In February 2002, a piece of ice sheet biger than the state of Rhode island disintegrated in 30 days. This ice sheet

1. is called the Ross ice sheet and is in antarctica.
2. is called the Ross ice sheet and is located in Greenland.
3. is called the Larsen B ice sheet and is located in Greenland.
4. is called the Larsen B ice sheet and is located in Antarctica.

The Vikings left greenland because

1. the innuits were mean to them.
2. they couldn't get fresh water.
3. they were defeated by the spanish.
4. of a cold snap which lasted for 500 years.

One piece of evidence that humans have influenced global warming is that

1. the ocean depths have cooled while the surface has gotten hotter.
2. the troposphere (the lower region of the atmosphere) has gotten warmer while the stratosphere above it has cooled.
3. algea blooms in the oceans have become more common.
4. the amount of carbon dioxide in the atmosphere has increased.