Nasa has been measuring the Ice extent for three decades now and the NSIDC offers a nice chart for displaying the annual variation in ice extent.

You can also obtain some interesting data in spreadsheets that can be downloaded.

However, remember a few important things:

  • Ice coverage varies hugely on an annual basis – winter ice extent is 3x larger than summer ice extent. And the reason for this is obvious. The planet’s axial tilt causes the poles to have 100% of daily sunlight during the summer and 0% of sunlight in the winter.
  • Year on year variation is also quite large
  • Satellite measurement of ice extent is relatively new and we haven’t been measuring change long enough to show the behaviour of even one cycle. i.e. Atlantic mult-decadal Oscillation (AMDO) cycle has 30 years of warming and 30 years of cooling. It is entirely possible that we have only observed the 30 years of warming.
  • While Arctic ice extent was declining during this period, Antarctic ice has been growing, which is kind of surprising for a warming earth. I would like to explore more into the possibility of oscillations between the northern and the southern hemispheres.




Ice, Arctic, Antarctic