The total volume of water contained in just those icebergs is over 5,000 Giga-tonnes, more than twice the estimated annual turnover of ice for the whole Antarctic continent. This is equivalent to sufficient water to supply all of the world's water needs, agricultural, industrial, and domestic, for more than a year. The estimated annual average accumulation of snow on the ice sheet, and therefore average annual turnover of ice, is around 2,500 Gt. While the scale of these events and the volumes are immense, the calving of this many very large icebergs is believed to be the consequence of a natural progression of events that occur in ice shelves, and quite unrelated to 'Global warming' or 'Greenhouse' effects. Mean annual air temperatures at the ice shelf fronts, between latitudes of 75 S and 78 S, are around -20 C, and summer air temperatures rarely reach melting point.
Ocean temperatures are at, or close to, freezing throughout the year.
Calving of ice from any section of the front of an ice shelf may occur frequently and produce a few or many small icebergs, or occur rarely and produce one or a few very large icebergs. Typical period of calving for a section of Ross or Ronne Ice Shelf appears to be around several decades. For the whole of Antarctica, very large icebergs with a length of several tens of kilometres can be expected to be produced several times a decade. These changes have accompanied a warming of several degrees observed since the 1940s in the Peninsula region, with mean summer temperatures approaching 0 C, and significant melt water production on the surface of many of the ice shelves. There is much to be learnt from observing these calving events and the evolution of the resulting icebergs.