Scientists talk about the evidence that supports their concerns that our planet is warming.
Select ALL of the statements that can be considered signs of global warming.
The concentration of carbon dioxide is at 400 ppm today. It has never been more than 300 ppm in the past 800,000 years.
Global sea level rose about 6.7 in. in the past century. The rate in the past decade, however, is nearly double that of the past century.
Since 1880, the 10 hottest years on record have been in the past 17 years.
Antarctica lost about 36 cubic miles of ice between 2002 and 2005
Since the beginning of the industrial revolution in the 1880s, the acidity of surface ocean waters has increased by about 30 percent.
The area covered by sea ice in the arctic at the end of summer has shrunk by about 40% since 1979
Currently, 37 glaciers in Glacier National Park are retreating.
Since 1990, data shows that birds are beginning their northern migration earlier and earlier each year - particularly birds that migrate over shorter distances. They are having trouble finding their normal food sources at their destination.
The amount of heavy downpours has increased 74% in New England from 1958 to 2011.