w some information that 
shows the thickness of long-term perennial ice in the north, and we now 
have very, very conclusive evidence that that ice is melting 
significantly.
  This is a graph showing the extent and thickness of the ice cover in 
the Arctic in various locations during the 1950s, 1960s, and 1970s 
compared to the thickness with observations taken in the last 15 years. 
The blue, for instance, at the North Pole, shows the meters, just under 
4 meters of thickness of ice at the North Pole on a