In part 1 of this series ‘Measuring the Surface Air Temperature’ I wrote that James Hansen of NASA’s Goddard Space Institute explains that it is not easy to measure surface air temperature particularly in the presence of vegetation because the temperature above the vegetation may be very different from the temperature below the vegetation.

So, I thought, maybe it is easier to measure the surface temperature where there is not much vegetation, for example, at the Antarctic.

But apparently knowing the average temperatures on Antarctica has its own challenge including the sparseness of ground-based weather stations particularly in the continent’s high altitude interior and the harsh environment also takes its toll on equipment.

So NASA relies on satellites that measure energy radiated from the ice surface and estimate a level of uncertainty in these measurements between 2-3 degree Celsius (read more here).

Given this level of uncertainty I find it extraordinary that NASA can suggest a warming trend of a fraction of a degree over the last 20 years in the following image.

Bill Kininmonth, former head of Australia's Bureau of Meteorology's National Climate Centre, recently emailed me that because it is very difficult to assess surface temperature over ice surfaces using satellite radiometers it is more realistic to consider sea surface temperatures and to also exclude regions of seasonal sea ice.

In the same email he provided the following image of the sea surface temperatures.

Bill also explained that the Larsen B ice shelf at the Antarctic shattered rather than melted earlier this year, with the comment “shattering is not related to melting”.