NSIDC's State of the Cryosphere provides an overview of the status of snow, ice, and permafrost as indicators of climate change. This site provides time-series data for Northern Hemisphere snow cover, mountain glacier fluctuations, sea ice extent and concentration, changes in ice shelves, and global sea level. It also provides a snapshot of current permafrost conditions.
Introduction: Are global temperatures rising?
Northern Hemisphere Snow: What satellite sensors are telling us about snow cover
Glaciers: Mountain glacier fluctuations
Permafrost and Frozen Ground: Insights from a Northern Hemisphere map and field observations
Sea Ice: What satellite sensors are telling us about global sea ice extent and concentration
Ice Shelves: Rapid response to climate change
Ice Sheets: Is ice sheet mass changing?
Sea Level: Is global sea level rising?
NSIDC Data via Google Earth
Download NSIDC data (KML file, 5.2 KB) for viewing NSIDC data in Google Earth (includes links to snow and ice, permafrost and glacier data sets). For details and instructions, see View NSIDC Data on Virtual Globes: Google Earth.