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?
What satellite sensors are telling us about snow cover
Mountain glacier fluctuations
Insights from a Northern Hemisphere map and field observations
What satellite sensors are telling us about global sea ice extent and concentration
Rapid response to climate change
Is global sea level rising?
NSIDC Data via Google Earth
Download NSIDC data (KML file, 5.6 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.
Additional science content: Mark Dyurgerov, James Maslanik, Mark Meier, Walt Meier, Ted Scambos, Mark Serreze, Julienne Stroeve, Tingjun Zhang