What’s Happening To Antarctic Ice Sheets?

By Paul Homewood 

 

 

 

What is happening to the Antarctic ice sheets? Are they really all melting?

 

To answer the question, we first need to go back and take a look at Jay Zwally’s paper in 2012, Mass Gains of the Antarctic Ice Sheet Exceed Losses. He found that:

 

During 2003 to 2008, the mass gain of the Antarctic ice sheet from snow accumulation exceeded the mass loss from ice discharge by 49 Gt/yr (2.5% of input), as derived from ICESat laser measurements of elevation change. The net gain (86 Gt/yr) over the West Antarctic (WA) and East Antarctic ice sheets (WA and EA) is essentially unchanged from revised results for 1992 to 2001 from ERS radar altimetry.

Imbalances in individual drainage systems (DS) are large (-68% to +103% of input), as are temporal changes (-39% to +44%). The recent 90 Gt/yr loss from three DS (Pine Island, Thwaites-Smith, and Marie-Bryd Coast) of WA exceeds the earlier 61 Gt/yr loss, consistent with reports of accelerating ice flow and dynamic thinning. Similarly, the recent 24 Gt/yr loss from three DS in the Antarctic Peninsula (AP) is consistent with glacier accelerations following breakup of the Larsen B and other ice shelves. In contrast, net increases in the five other DS of WA and AP and three of the 16 DS in East Antarctica (EA) exceed the increased losses. Alternate interpretations of the mass changes driven by accumulation variations are given using results from atmospheric-model re-analysis and a parameterization based on 5% change in accumulation per degree of observed surface temperature change. A slow increase in snowfall with climate warming, consistent with model predictions, may be offsetting increased dynamic losses.

 

So, in overall terms, losses from certain glaciers in Western Antarctica have been more than offset by growth of ice sheets in other parts of Antarctica, probably due to increased snowfall. Furthermore, trends in recent years have been consistent with the previous decade.

 

There are other papers which claim to arrive at different results, and show net losses, but all these prove is that measurements of ice mass are inherently unreliable, particularly over such short periods of time.

 

It also needs to be remembered that the Antarctic was affected by the Little Ice Age, just as much as the rest of the world was. Indeed, HH Lamb writes that the peak cold there was probably later than elsewhere, as late as 1900:

Later in the 19thC, in the 1850’s and around 1900, the southern sea ice extended farther north and there were many accounts from the sailing ships of those days of sightings of the great tabular icebergs calved from the Antarctic inland ice drifting to much lower latitudes, off the River Plate and approaching the other southern continents.

[Climate, History and the Modern World – pp257)

 

We pretend we know what is going on in Antarctica, based on just a few years’ worth of dodgy data, but ignore the much longer term perspectives. Even Prof Turner of the British Antarctic Survey had to admit:

“Pine Island seems to be an ongoing retreat that could have been going on for 10,000 years”